Improve the editor theme

The editor theme now makes use of rounded corners and less borders
to follow modern visual trends.

The default theme's colors were also tweaked to make the blue hue
more subtle (similar to the Arc theme, which was removed as a
consequence). The Alien theme was replaced by a Breeze Dark theme,
which should blend in well with the KDE theme.

16 files changed, 216 insertions, 225 deletions

diff --git a/editor/create_dialog.cpp b/editor/create_dialog.cpp
index 711072f4b2..1c0a55e4ec 100644
--- a/editor/create_dialog.cpp
+++ b/editor/create_dialog.cpp
@@ -708,7 +708,6 @@ CreateDialog::CreateDialog() {
 	search_hb->add_child(search_box);
 
 	favorite = memnew(Button);
-	favorite->set_flat(true);
 	favorite->set_toggle_mode(true);
 	favorite->set_tooltip(TTR("(Un)favorite selected item."));
 	favorite->connect("pressed", callable_mp(this, &CreateDialog::_favorite_toggled));
diff --git a/editor/editor_node.cpp b/editor/editor_node.cpp
index 6137617564..1202de282c 100644
--- a/editor/editor_node.cpp
+++ b/editor/editor_node.cpp
@@ -6479,7 +6479,6 @@ EditorNode::EditorNode() {
 
 	// Toggle for video driver
 	video_driver = memnew(OptionButton);
-	video_driver->set_flat(true);
 	video_driver->set_focus_mode(Control::FOCUS_NONE);
 	video_driver->connect("item_selected", callable_mp(this, &EditorNode::_video_driver_selected));
 	video_driver->add_theme_font_override("font", gui_base->get_theme_font("bold", "EditorFonts"));
diff --git a/editor/editor_properties_array_dict.cpp b/editor/editor_properties_array_dict.cpp
index de688f2709..fb2980c948 100644
--- a/editor/editor_properties_array_dict.cpp
+++ b/editor/editor_properties_array_dict.cpp
@@ -575,7 +575,6 @@ EditorPropertyArray::EditorPropertyArray() {
 	object.instance();
 	page_len = int(EDITOR_GET("interface/inspector/max_array_dictionary_items_per_page"));
 	edit = memnew(Button);
-	edit->set_flat(true);
 	edit->set_h_size_flags(SIZE_EXPAND_FILL);
 	edit->set_clip_text(true);
 	edit->connect("pressed", callable_mp(this, &EditorPropertyArray::_edit_pressed));
@@ -1070,7 +1069,6 @@ EditorPropertyDictionary::EditorPropertyDictionary() {
 	object.instance();
 	page_len = int(EDITOR_GET("interface/inspector/max_array_dictionary_items_per_page"));
 	edit = memnew(Button);
-	edit->set_flat(true);
 	edit->set_h_size_flags(SIZE_EXPAND_FILL);
 	edit->set_clip_text(true);
 	edit->connect("pressed", callable_mp(this, &EditorPropertyDictionary::_edit_pressed));
diff --git a/editor/editor_settings.cpp b/editor/editor_settings.cpp
index 4ddae7c062..1c94e65b66 100644
--- a/editor/editor_settings.cpp
+++ b/editor/editor_settings.cpp
@@ -437,7 +437,7 @@ void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 
 	// Theme
 	_initial_set("interface/theme/preset", "Default");
-	hints["interface/theme/preset"] = PropertyInfo(Variant::STRING, "interface/theme/preset", PROPERTY_HINT_ENUM, "Default,Alien,Arc,Godot 2,Grey,Light,Solarized (Dark),Solarized (Light),Custom", PROPERTY_USAGE_DEFAULT);
+	hints["interface/theme/preset"] = PropertyInfo(Variant::STRING, "interface/theme/preset", PROPERTY_HINT_ENUM, "Default,Breeze Dark,Godot 2,Grey,Light,Solarized (Dark),Solarized (Light),Custom", PROPERTY_USAGE_DEFAULT);
 	_initial_set("interface/theme/icon_and_font_color", 0);
 	hints["interface/theme/icon_and_font_color"] = PropertyInfo(Variant::INT, "interface/theme/icon_and_font_color", PROPERTY_HINT_ENUM, "Auto,Dark,Light", PROPERTY_USAGE_DEFAULT);
 	_initial_set("interface/theme/base_color", Color(0.2, 0.23, 0.31));
@@ -450,10 +450,10 @@ void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 	hints["interface/theme/icon_saturation"] = PropertyInfo(Variant::FLOAT, "interface/theme/icon_saturation", PROPERTY_HINT_RANGE, "0,2,0.01", PROPERTY_USAGE_DEFAULT);
 	_initial_set("interface/theme/relationship_line_opacity", 0.1);
 	hints["interface/theme/relationship_line_opacity"] = PropertyInfo(Variant::FLOAT, "interface/theme/relationship_line_opacity", PROPERTY_HINT_RANGE, "0.00, 1, 0.01");
-	_initial_set("interface/theme/highlight_tabs", false);
-	_initial_set("interface/theme/border_size", 1);
-	_initial_set("interface/theme/use_graph_node_headers", false);
+	_initial_set("interface/theme/border_size", 0);
 	hints["interface/theme/border_size"] = PropertyInfo(Variant::INT, "interface/theme/border_size", PROPERTY_HINT_RANGE, "0,2,1", PROPERTY_USAGE_DEFAULT);
+	_initial_set("interface/theme/corner_radius", 3);
+	hints["interface/theme/corner_radius"] = PropertyInfo(Variant::INT, "interface/theme/corner_radius", PROPERTY_HINT_RANGE, "0,6,1", PROPERTY_USAGE_DEFAULT);
 	_initial_set("interface/theme/additional_spacing", 0);
 	hints["interface/theme/additional_spacing"] = PropertyInfo(Variant::FLOAT, "interface/theme/additional_spacing", PROPERTY_HINT_RANGE, "0,5,0.1", PROPERTY_USAGE_DEFAULT);
 	_initial_set("interface/theme/custom_theme", "");
diff --git a/editor/editor_themes.cpp b/editor/editor_themes.cpp
index 7cc9ebd63e..44b4a9f688 100644
--- a/editor/editor_themes.cpp
+++ b/editor/editor_themes.cpp
@@ -65,9 +65,12 @@ static Ref<StyleBoxEmpty> make_empty_stylebox(float p_margin_left = -1, float p_
 	return style;
 }
 
-static Ref<StyleBoxFlat> make_flat_stylebox(Color p_color, float p_margin_left = -1, float p_margin_top = -1, float p_margin_right = -1, float p_margin_bottom = -1) {
+static Ref<StyleBoxFlat> make_flat_stylebox(Color p_color, float p_margin_left = -1, float p_margin_top = -1, float p_margin_right = -1, float p_margin_bottom = -1, int p_corner_width = 0) {
 	Ref<StyleBoxFlat> style(memnew(StyleBoxFlat));
 	style->set_bg_color(p_color);
+	// Adjust level of detail based on the corners' effective sizes.
+	style->set_corner_detail(Math::ceil(1.5 * p_corner_width * EDSCALE));
+	style->set_corner_radius_all(p_corner_width);
 	style->set_default_margin(SIDE_LEFT, p_margin_left * EDSCALE);
 	style->set_default_margin(SIDE_RIGHT, p_margin_right * EDSCALE);
 	style->set_default_margin(SIDE_BOTTOM, p_margin_bottom * EDSCALE);
@@ -286,9 +289,9 @@ void editor_register_and_generate_icons(Ref<Theme> p_theme, bool p_dark_theme =
 Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	Ref<Theme> theme = Ref<Theme>(memnew(Theme));
 
-	const float default_contrast = 0.25;
+	const float default_contrast = 0.3;
 
-	//Theme settings
+	// Theme settings
 	Color accent_color = EDITOR_GET("interface/theme/accent_color");
 	Color base_color = EDITOR_GET("interface/theme/base_color");
 	float contrast = EDITOR_GET("interface/theme/contrast");
@@ -297,56 +300,47 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 
 	String preset = EDITOR_GET("interface/theme/preset");
 
-	bool highlight_tabs = EDITOR_GET("interface/theme/highlight_tabs");
 	int border_size = EDITOR_GET("interface/theme/border_size");
-
-	bool use_gn_headers = EDITOR_GET("interface/theme/use_graph_node_headers");
+	int corner_radius = EDITOR_GET("interface/theme/corner_radius");
 
 	Color preset_accent_color;
 	Color preset_base_color;
 	float preset_contrast = 0;
 
-	// Please, use alphabet order if you've added new theme here(After "Default" and "Custom")
+	// Please use alphabetical order if you're adding a new theme here
+	// (after "Custom")
 
-	if (preset == "Default") {
-		preset_accent_color = Color(0.41, 0.61, 0.91);
-		preset_base_color = Color(0.2, 0.23, 0.31);
-		preset_contrast = default_contrast;
-	} else if (preset == "Custom") {
+	if (preset == "Custom") {
 		accent_color = EDITOR_GET("interface/theme/accent_color");
 		base_color = EDITOR_GET("interface/theme/base_color");
 		contrast = EDITOR_GET("interface/theme/contrast");
-	} else if (preset == "Alien") {
-		preset_accent_color = Color(0.11, 1.0, 0.6);
-		preset_base_color = Color(0.18, 0.22, 0.25);
-		preset_contrast = 0.25;
-	} else if (preset == "Arc") {
-		preset_accent_color = Color(0.32, 0.58, 0.89);
-		preset_base_color = Color(0.22, 0.24, 0.29);
-		preset_contrast = 0.25;
+	} else if (preset == "Breeze Dark") {
+		preset_accent_color = Color(0.26, 0.76, 1.00);
+		preset_base_color = Color(0.24, 0.26, 0.28);
+		preset_contrast = default_contrast;
 	} else if (preset == "Godot 2") {
 		preset_accent_color = Color(0.53, 0.67, 0.89);
 		preset_base_color = Color(0.24, 0.23, 0.27);
-		preset_contrast = 0.25;
+		preset_contrast = default_contrast;
 	} else if (preset == "Grey") {
-		preset_accent_color = Color(0.72, 0.89, 1.0);
+		preset_accent_color = Color(0.72, 0.89, 1.00);
 		preset_base_color = Color(0.24, 0.24, 0.24);
-		preset_contrast = 0.2;
+		preset_contrast = default_contrast;
 	} else if (preset == "Light") {
-		preset_accent_color = Color(0.13, 0.44, 1.0);
-		preset_base_color = Color(1, 1, 1);
+		preset_accent_color = Color(0.18, 0.50, 1.00);
+		preset_base_color = Color(1.00, 1.00, 1.00);
 		preset_contrast = 0.08;
 	} else if (preset == "Solarized (Dark)") {
 		preset_accent_color = Color(0.15, 0.55, 0.82);
-		preset_base_color = Color(0.03, 0.21, 0.26);
-		preset_contrast = 0.23;
+		preset_base_color = Color(0.04, 0.23, 0.27);
+		preset_contrast = default_contrast;
 	} else if (preset == "Solarized (Light)") {
 		preset_accent_color = Color(0.15, 0.55, 0.82);
 		preset_base_color = Color(0.99, 0.96, 0.89);
-		preset_contrast = 0.06;
+		preset_contrast = 0.08;
 	} else { // Default
-		preset_accent_color = Color(0.41, 0.61, 0.91);
-		preset_base_color = Color(0.2, 0.23, 0.31);
+		preset_accent_color = Color(0.44, 0.73, 0.98);
+		preset_base_color = Color(0.21, 0.24, 0.29);
 		preset_contrast = default_contrast;
 	}
 
@@ -358,12 +352,13 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 		EditorSettings::get_singleton()->set_initial_value("interface/theme/base_color", base_color);
 		EditorSettings::get_singleton()->set_initial_value("interface/theme/contrast", contrast);
 	}
+
 	EditorSettings::get_singleton()->set_manually("interface/theme/preset", preset);
 	EditorSettings::get_singleton()->set_manually("interface/theme/accent_color", accent_color);
 	EditorSettings::get_singleton()->set_manually("interface/theme/base_color", base_color);
 	EditorSettings::get_singleton()->set_manually("interface/theme/contrast", contrast);
 
-	//Colors
+	// Colors
 	bool dark_theme = EditorSettings::get_singleton()->is_dark_theme();
 
 	const Color dark_color_1 = base_color.lerp(Color(0, 0, 0, 1), contrast);
@@ -372,14 +367,14 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 
 	const Color background_color = dark_color_2;
 
-	// white (dark theme) or black (light theme), will be used to generate the rest of the colors
+	// White (dark theme) or black (light theme), will be used to generate the rest of the colors
 	const Color mono_color = dark_theme ? Color(1, 1, 1) : Color(0, 0, 0);
 
 	const Color contrast_color_1 = base_color.lerp(mono_color, MAX(contrast, default_contrast));
 	const Color contrast_color_2 = base_color.lerp(mono_color, MAX(contrast * 1.5, default_contrast * 1.5));
 
 	const Color font_color = mono_color.lerp(base_color, 0.25);
-	const Color font_hover_color = mono_color.lerp(base_color, 0.15);
+	const Color font_hover_color = mono_color.lerp(base_color, 0.125);
 	const Color font_disabled_color = Color(mono_color.r, mono_color.g, mono_color.b, 0.3);
 	const Color selection_color = accent_color * Color(1, 1, 1, 0.4);
 	const Color disabled_color = mono_color.inverted().lerp(base_color, 0.7);
@@ -393,8 +388,7 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	icon_pressed_color.a = 1.0;
 
 	const Color separator_color = Color(mono_color.r, mono_color.g, mono_color.b, 0.1);
-
-	const Color highlight_color = Color(mono_color.r, mono_color.g, mono_color.b, 0.2);
+	const Color highlight_color = Color(accent_color.r, accent_color.g, accent_color.b, 0.275);
 
 	float prev_icon_saturation = theme->has_color("icon_saturation", "Editor") ? theme->get_color("icon_saturation", "Editor").r : 1.0;
 
@@ -447,35 +441,35 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_constant("thumb_size", "Editor", thumb_size);
 	theme->set_constant("dark_theme", "Editor", dark_theme);
 
-	//Register icons + font
+	// Register icons + font
 
-	// the resolution and the icon color (dark_theme bool) has not changed, so we do not regenerate the icons
+	// The resolution and the icon color (dark_theme bool) has not changed, so we do not regenerate the icons.
 	if (p_theme != nullptr && fabs(p_theme->get_constant("scale", "Editor") - EDSCALE) < 0.00001 && (bool)p_theme->get_constant("dark_theme", "Editor") == dark_theme && prev_icon_saturation == icon_saturation) {
-		// register already generated icons
+		// Register already generated icons.
 		for (int i = 0; i < editor_icons_count; i++) {
 			theme->set_icon(editor_icons_names[i], "EditorIcons", p_theme->get_icon(editor_icons_names[i], "EditorIcons"));
 		}
 	} else {
 		editor_register_and_generate_icons(theme, dark_theme, thumb_size, false, icon_saturation);
 	}
-	// thumbnail size has changed, so we regenerate the medium sizes
+	// Thumbnail size has changed, so we regenerate the medium sizes
 	if (p_theme != nullptr && fabs((double)p_theme->get_constant("thumb_size", "Editor") - thumb_size) > 0.00001) {
 		editor_register_and_generate_icons(p_theme, dark_theme, thumb_size, true);
 	}
 
 	editor_register_fonts(theme);
 
-	// Highlighted tabs and border width
-	Color tab_color = highlight_tabs ? base_color.lerp(font_color, contrast) : base_color;
 	// Ensure borders are visible when using an editor scale below 100%.
-	const int border_width = CLAMP(border_size, 0, 3) * MAX(1, EDSCALE);
-
+	const int border_width = CLAMP(border_size, 0, 2) * MAX(1, EDSCALE);
+	const int corner_width = CLAMP(corner_radius, 0, 6) * EDSCALE;
 	const int default_margin_size = 4;
-	const int margin_size_extra = default_margin_size + CLAMP(border_size, 0, 3);
+	const int margin_size_extra = default_margin_size + CLAMP(border_size, 0, 2);
 
-	// styleboxes
-	// this is the most commonly used stylebox, variations should be made as duplicate of this
-	Ref<StyleBoxFlat> style_default = make_flat_stylebox(base_color, default_margin_size, default_margin_size, default_margin_size, default_margin_size);
+	// Styleboxes
+	// This is the most commonly used stylebox, variations should be made as duplicate of this
+	Ref<StyleBoxFlat> style_default = make_flat_stylebox(base_color, default_margin_size, default_margin_size, default_margin_size, default_margin_size, corner_width);
+	// Work around issue about antialiased edges being blurrier (GH-35279).
+	style_default->set_anti_aliased(false);
 	style_default->set_border_width_all(border_width);
 	style_default->set_border_color(base_color);
 	style_default->set_draw_center(true);
@@ -483,11 +477,13 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	// Button and widgets
 	const float extra_spacing = EDITOR_GET("interface/theme/additional_spacing");
 
+	const Vector2 widget_default_margin = Vector2(extra_spacing + 6, extra_spacing + default_margin_size + 1) * EDSCALE;
+
 	Ref<StyleBoxFlat> style_widget = style_default->duplicate();
-	style_widget->set_default_margin(SIDE_LEFT, (extra_spacing + 6) * EDSCALE);
-	style_widget->set_default_margin(SIDE_TOP, (extra_spacing + default_margin_size) * EDSCALE);
-	style_widget->set_default_margin(SIDE_RIGHT, (extra_spacing + 6) * EDSCALE);
-	style_widget->set_default_margin(SIDE_BOTTOM, (extra_spacing + default_margin_size) * EDSCALE);
+	style_widget->set_default_margin(SIDE_LEFT, widget_default_margin.x);
+	style_widget->set_default_margin(SIDE_TOP, widget_default_margin.y);
+	style_widget->set_default_margin(SIDE_RIGHT, widget_default_margin.x);
+	style_widget->set_default_margin(SIDE_BOTTOM, widget_default_margin.y);
 	style_widget->set_bg_color(dark_color_1);
 	style_widget->set_border_color(dark_color_2);
 
@@ -496,69 +492,82 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	style_widget_disabled->set_bg_color(disabled_bg_color);
 
 	Ref<StyleBoxFlat> style_widget_focus = style_widget->duplicate();
+	style_widget_focus->set_draw_center(false);
+	style_widget_focus->set_border_width_all(Math::round(2 * MAX(1, EDSCALE)));
 	style_widget_focus->set_border_color(accent_color);
 
 	Ref<StyleBoxFlat> style_widget_pressed = style_widget->duplicate();
-	style_widget_pressed->set_border_color(accent_color);
+	style_widget_pressed->set_bg_color(dark_color_1.darkened(0.125));
 
 	Ref<StyleBoxFlat> style_widget_hover = style_widget->duplicate();
-	style_widget_hover->set_border_color(contrast_color_1);
+	style_widget_hover->set_bg_color(mono_color * Color(1, 1, 1, 0.11));
+	style_widget_hover->set_border_color(mono_color * Color(1, 1, 1, 0.05));
 
-	// style for windows, popups, etc..
+	// Style for windows, popups, etc..
 	Ref<StyleBoxFlat> style_popup = style_default->duplicate();
-	const int popup_margin_size = default_margin_size * EDSCALE * 2;
+	const int popup_margin_size = default_margin_size * EDSCALE * 3;
 	style_popup->set_default_margin(SIDE_LEFT, popup_margin_size);
 	style_popup->set_default_margin(SIDE_TOP, popup_margin_size);
 	style_popup->set_default_margin(SIDE_RIGHT, popup_margin_size);
 	style_popup->set_default_margin(SIDE_BOTTOM, popup_margin_size);
 	style_popup->set_border_color(contrast_color_1);
-	style_popup->set_border_width_all(MAX(EDSCALE, border_width));
 	const Color shadow_color = Color(0, 0, 0, dark_theme ? 0.3 : 0.1);
 	style_popup->set_shadow_color(shadow_color);
 	style_popup->set_shadow_size(4 * EDSCALE);
 
 	Ref<StyleBoxLine> style_popup_separator(memnew(StyleBoxLine));
 	style_popup_separator->set_color(separator_color);
-	style_popup_separator->set_grow_begin(popup_margin_size - MAX(EDSCALE, border_width));
-	style_popup_separator->set_grow_end(popup_margin_size - MAX(EDSCALE, border_width));
-	style_popup_separator->set_thickness(MAX(EDSCALE, border_width));
+	style_popup_separator->set_grow_begin(popup_margin_size - MAX(Math::round(EDSCALE), border_width));
+	style_popup_separator->set_grow_end(popup_margin_size - MAX(Math::round(EDSCALE), border_width));
+	style_popup_separator->set_thickness(MAX(Math::round(EDSCALE), border_width));
 
 	Ref<StyleBoxLine> style_popup_labeled_separator_left(memnew(StyleBoxLine));
-	style_popup_labeled_separator_left->set_grow_begin(popup_margin_size - MAX(EDSCALE, border_width));
+	style_popup_labeled_separator_left->set_grow_begin(popup_margin_size - MAX(Math::round(EDSCALE), border_width));
 	style_popup_labeled_separator_left->set_color(separator_color);
-	style_popup_labeled_separator_left->set_thickness(MAX(EDSCALE, border_width));
+	style_popup_labeled_separator_left->set_thickness(MAX(Math::round(EDSCALE), border_width));
 
 	Ref<StyleBoxLine> style_popup_labeled_separator_right(memnew(StyleBoxLine));
-	style_popup_labeled_separator_right->set_grow_end(popup_margin_size - MAX(EDSCALE, border_width));
+	style_popup_labeled_separator_right->set_grow_end(popup_margin_size - MAX(Math::round(EDSCALE), border_width));
 	style_popup_labeled_separator_right->set_color(separator_color);
-	style_popup_labeled_separator_right->set_thickness(MAX(EDSCALE, border_width));
+	style_popup_labeled_separator_right->set_thickness(MAX(Math::round(EDSCALE), border_width));
 
 	Ref<StyleBoxEmpty> style_empty = make_empty_stylebox(default_margin_size, default_margin_size, default_margin_size, default_margin_size);
 
 	// Tabs
 
-	const int tab_default_margin_side = 10 * EDSCALE + extra_spacing * EDSCALE;
-	const int tab_default_margin_vertical = 5 * EDSCALE + extra_spacing * EDSCALE;
-
 	Ref<StyleBoxFlat> style_tab_selected = style_widget->duplicate();
 
-	style_tab_selected->set_border_width_all(border_width);
-	style_tab_selected->set_border_width(SIDE_BOTTOM, 0);
-	style_tab_selected->set_border_color(dark_color_3);
-	style_tab_selected->set_expand_margin_size(SIDE_BOTTOM, border_width);
-	style_tab_selected->set_default_margin(SIDE_LEFT, tab_default_margin_side);
-	style_tab_selected->set_default_margin(SIDE_RIGHT, tab_default_margin_side);
-	style_tab_selected->set_default_margin(SIDE_BOTTOM, tab_default_margin_vertical);
-	style_tab_selected->set_default_margin(SIDE_TOP, tab_default_margin_vertical);
-	style_tab_selected->set_bg_color(tab_color);
+	// Add a highlight line at the top of the selected tab.
+	style_tab_selected->set_border_width_all(0);
+	style_tab_selected->set_border_width(SIDE_TOP, Math::round(2 * EDSCALE));
+	// Make the highlight line prominent, but not too prominent as to not be distracting.
+	style_tab_selected->set_border_color(dark_color_2.lerp(accent_color, 0.75));
+	// Don't round the top corners to avoid creating a small blank space between the tabs and the main panel.
+	// This also makes the top highlight look better.
+	style_tab_selected->set_corner_radius_all(0);
+
+	// Prevent visible artifacts and cover the top-left rounded corner of the panel below the tab if selected
+	// We can't prevent them with both rounded corners and non-zero border width, though
+	style_tab_selected->set_expand_margin_size(SIDE_BOTTOM, corner_width > 0 ? corner_width : border_width);
+
+	style_tab_selected->set_default_margin(SIDE_LEFT, widget_default_margin.x + 2 * EDSCALE);
+	style_tab_selected->set_default_margin(SIDE_RIGHT, widget_default_margin.x + 2 * EDSCALE);
+	style_tab_selected->set_default_margin(SIDE_BOTTOM, widget_default_margin.y);
+	style_tab_selected->set_default_margin(SIDE_TOP, widget_default_margin.y);
+	style_tab_selected->set_bg_color(base_color);
 
 	Ref<StyleBoxFlat> style_tab_unselected = style_tab_selected->duplicate();
 	style_tab_unselected->set_bg_color(dark_color_1);
+	style_tab_unselected->set_expand_margin_size(SIDE_BOTTOM, 0);
+	// Add some spacing between unselected tabs to make them easier to distinguish from each other
 	style_tab_unselected->set_border_color(dark_color_2);
+	style_tab_unselected->set_border_width(SIDE_LEFT, Math::round(2 * EDSCALE));
+	style_tab_unselected->set_border_width(SIDE_RIGHT, Math::round(2 * EDSCALE));
 
 	Ref<StyleBoxFlat> style_tab_disabled = style_tab_selected->duplicate();
 	style_tab_disabled->set_bg_color(disabled_bg_color);
-	style_tab_disabled->set_border_color(disabled_color);
+	style_tab_disabled->set_expand_margin_size(SIDE_BOTTOM, 0);
+	style_tab_disabled->set_border_color(disabled_bg_color);
 
 	// Editor background
 	Color background_color_opaque = background_color;
@@ -566,10 +575,7 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_stylebox("Background", "EditorStyles", make_flat_stylebox(background_color_opaque, default_margin_size, default_margin_size, default_margin_size, default_margin_size));
 
 	// Focus
-	Ref<StyleBoxFlat> style_focus = style_default->duplicate();
-	style_focus->set_draw_center(false);
-	style_focus->set_border_color(contrast_color_2);
-	theme->set_stylebox("Focus", "EditorStyles", style_focus);
+	theme->set_stylebox("Focus", "EditorStyles", style_widget_focus);
 
 	// Menu
 	Ref<StyleBoxFlat> style_menu = style_widget->duplicate();
@@ -585,33 +591,25 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	// Play button group
 	theme->set_stylebox("PlayButtonPanel", "EditorStyles", style_empty);
 
-	//MenuButton
-	Ref<StyleBoxFlat> style_menu_hover_border = style_widget->duplicate();
-	style_menu_hover_border->set_draw_center(false);
-	style_menu_hover_border->set_border_width_all(0);
-	style_menu_hover_border->set_border_width(SIDE_BOTTOM, border_width);
-	style_menu_hover_border->set_border_color(accent_color);
-
-	Ref<StyleBoxFlat> style_menu_hover_bg = style_widget->duplicate();
-	style_menu_hover_bg->set_border_width_all(0);
-	style_menu_hover_bg->set_bg_color(dark_color_1);
-
 	theme->set_stylebox("normal", "MenuButton", style_menu);
-	theme->set_stylebox("hover", "MenuButton", style_menu);
+	theme->set_stylebox("hover", "MenuButton", style_widget_hover);
 	theme->set_stylebox("pressed", "MenuButton", style_menu);
 	theme->set_stylebox("focus", "MenuButton", style_menu);
 	theme->set_stylebox("disabled", "MenuButton", style_menu);
 
 	theme->set_stylebox("normal", "PopupMenu", style_menu);
-	theme->set_stylebox("hover", "PopupMenu", style_menu_hover_bg);
-	theme->set_stylebox("pressed", "PopupMenu", style_menu);
+
+	Ref<StyleBoxFlat> style_menu_hover = style_widget_hover->duplicate();
+	// Don't use rounded corners for hover highlights since the StyleBox touches the PopupMenu's edges.
+	style_menu_hover->set_corner_radius_all(0);
+	theme->set_stylebox("hover", "PopupMenu", style_menu_hover);
 	theme->set_stylebox("focus", "PopupMenu", style_menu);
 	theme->set_stylebox("disabled", "PopupMenu", style_menu);
 
 	theme->set_color("font_color", "MenuButton", font_color);
 	theme->set_color("font_hover_color", "MenuButton", font_hover_color);
 
-	theme->set_stylebox("MenuHover", "EditorStyles", style_menu_hover_border);
+	theme->set_stylebox("MenuHover", "EditorStyles", style_widget_hover);
 
 	// Buttons
 	theme->set_stylebox("normal", "Button", style_widget);
@@ -646,7 +644,7 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_color("font_disabled_color", "OptionButton", font_disabled_color);
 	theme->set_color("icon_hover_color", "OptionButton", icon_hover_color);
 	theme->set_icon("arrow", "OptionButton", theme->get_icon("GuiOptionArrow", "EditorIcons"));
-	theme->set_constant("arrow_margin", "OptionButton", default_margin_size * EDSCALE);
+	theme->set_constant("arrow_margin", "OptionButton", widget_default_margin.x - 2 * EDSCALE);
 	theme->set_constant("modulate_arrow", "OptionButton", true);
 	theme->set_constant("hseparation", "OptionButton", 4 * EDSCALE);
 
@@ -672,7 +670,7 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_color("font_disabled_color", "CheckButton", font_disabled_color);
 	theme->set_color("icon_hover_color", "CheckButton", icon_hover_color);
 
-	theme->set_constant("hseparation", "CheckButton", 4 * EDSCALE);
+	theme->set_constant("hseparation", "CheckButton", 8 * EDSCALE);
 	theme->set_constant("check_vadjust", "CheckButton", 0 * EDSCALE);
 
 	// Checkbox
@@ -697,7 +695,7 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_color("font_disabled_color", "CheckBox", font_disabled_color);
 	theme->set_color("icon_hover_color", "CheckBox", icon_hover_color);
 
-	theme->set_constant("hseparation", "CheckBox", 4 * EDSCALE);
+	theme->set_constant("hseparation", "CheckBox", 8 * EDSCALE);
 	theme->set_constant("check_vadjust", "CheckBox", 0 * EDSCALE);
 
 	// PopupDialog
@@ -794,12 +792,13 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 
 	// Tree & ItemList background
 	Ref<StyleBoxFlat> style_tree_bg = style_default->duplicate();
-	style_tree_bg->set_bg_color(dark_color_1);
+	// Make Trees easier to distinguish from other controls by using a darker background color.
+	style_tree_bg->set_bg_color(dark_color_1.lerp(dark_color_2, 0.5));
 	style_tree_bg->set_border_color(dark_color_3);
 	theme->set_stylebox("bg", "Tree", style_tree_bg);
 
-	const Color guide_color = Color(mono_color.r, mono_color.g, mono_color.b, 0.05);
-	Color relationship_line_color = Color(mono_color.r, mono_color.g, mono_color.b, relationship_line_opacity);
+	const Color guide_color = mono_color * Color(1, 1, 1, 0.05);
+	Color relationship_line_color = mono_color * Color(1, 1, 1, relationship_line_opacity);
 	// Tree
 	theme->set_icon("checked", "Tree", theme->get_icon("GuiChecked", "EditorIcons"));
 	theme->set_icon("unchecked", "Tree", theme->get_icon("GuiUnchecked", "EditorIcons"));
@@ -808,7 +807,7 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_icon("arrow_collapsed_mirrored", "Tree", theme->get_icon("GuiTreeArrowLeft", "EditorIcons"));
 	theme->set_icon("updown", "Tree", theme->get_icon("GuiTreeUpdown", "EditorIcons"));
 	theme->set_icon("select_arrow", "Tree", theme->get_icon("GuiDropdown", "EditorIcons"));
-	theme->set_stylebox("bg_focus", "Tree", style_focus);
+	theme->set_stylebox("bg_focus", "Tree", style_widget_focus);
 	theme->set_stylebox("custom_button", "Tree", make_empty_stylebox());
 	theme->set_stylebox("custom_button_pressed", "Tree", make_empty_stylebox());
 	theme->set_stylebox("custom_button_hover", "Tree", style_widget);
@@ -819,8 +818,9 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_color("guide_color", "Tree", guide_color);
 	theme->set_color("relationship_line_color", "Tree", relationship_line_color);
 	theme->set_color("drop_position_color", "Tree", accent_color);
-	theme->set_constant("vseparation", "Tree", (extra_spacing + default_margin_size) * EDSCALE);
-	theme->set_constant("hseparation", "Tree", (extra_spacing + default_margin_size) * EDSCALE);
+	theme->set_constant("vseparation", "Tree", widget_default_margin.y - EDSCALE);
+	theme->set_constant("hseparation", "Tree", 6 * EDSCALE);
+	theme->set_constant("guide_width", "Tree", border_width);
 	theme->set_constant("item_margin", "Tree", 3 * default_margin_size * EDSCALE);
 	theme->set_constant("button_margin", "Tree", default_margin_size * EDSCALE);
 	theme->set_constant("draw_relationship_lines", "Tree", relationship_line_opacity >= 0.01);
@@ -829,7 +829,7 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_constant("scroll_speed", "Tree", 12);
 
 	Ref<StyleBoxFlat> style_tree_btn = style_default->duplicate();
-	style_tree_btn->set_bg_color(contrast_color_1);
+	style_tree_btn->set_bg_color(highlight_color);
 	style_tree_btn->set_border_width_all(0);
 	theme->set_stylebox("button_pressed", "Tree", style_tree_btn);
 
@@ -882,14 +882,14 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_stylebox("cursor_unfocused", "ItemList", style_itemlist_cursor);
 	theme->set_stylebox("selected_focus", "ItemList", style_tree_focus);
 	theme->set_stylebox("selected", "ItemList", style_tree_selected);
-	theme->set_stylebox("bg_focus", "ItemList", style_focus);
+	theme->set_stylebox("bg_focus", "ItemList", style_widget_focus);
 	theme->set_stylebox("bg", "ItemList", style_itemlist_bg);
 	theme->set_color("font_color", "ItemList", font_color);
 	theme->set_color("font_selected_color", "ItemList", mono_color);
 	theme->set_color("guide_color", "ItemList", guide_color);
-	theme->set_constant("vseparation", "ItemList", 3 * EDSCALE);
-	theme->set_constant("hseparation", "ItemList", 3 * EDSCALE);
-	theme->set_constant("icon_margin", "ItemList", default_margin_size * EDSCALE);
+	theme->set_constant("vseparation", "ItemList", widget_default_margin.y - EDSCALE);
+	theme->set_constant("hseparation", "ItemList", 6 * EDSCALE);
+	theme->set_constant("icon_margin", "ItemList", 6 * EDSCALE);
 	theme->set_constant("line_separation", "ItemList", 3 * EDSCALE);
 
 	// Tabs & TabContainer
@@ -940,8 +940,8 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_stylebox("Content", "EditorStyles", style_content_panel_vp);
 
 	// Separators
-	theme->set_stylebox("separator", "HSeparator", make_line_stylebox(separator_color, border_width));
-	theme->set_stylebox("separator", "VSeparator", make_line_stylebox(separator_color, border_width, 0, 0, true));
+	theme->set_stylebox("separator", "HSeparator", make_line_stylebox(separator_color, MAX(Math::round(EDSCALE), border_width)));
+	theme->set_stylebox("separator", "VSeparator", make_line_stylebox(separator_color, MAX(Math::round(EDSCALE), border_width), 0, 0, true));
 
 	// Debugger
 
@@ -956,9 +956,23 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_stylebox("BottomPanelDebuggerOverride", "EditorStyles", style_panel_invisible_top);
 
 	// LineEdit
-	theme->set_stylebox("normal", "LineEdit", style_widget);
+
+	Ref<StyleBoxFlat> style_line_edit = style_widget->duplicate();
+	// Add a bottom line to make LineEdits more visible, especially in sectioned inspectors
+	// such as the Project Settings.
+	style_line_edit->set_border_width(SIDE_BOTTOM, Math::round(2 * EDSCALE));
+	style_line_edit->set_border_color(dark_color_2);
+	// Don't round the bottom corner to make the line look sharper.
+	style_tab_selected->set_corner_radius(CORNER_BOTTOM_LEFT, 0);
+	style_tab_selected->set_corner_radius(CORNER_BOTTOM_RIGHT, 0);
+
+	Ref<StyleBoxFlat> style_line_edit_disabled = style_line_edit->duplicate();
+	style_line_edit_disabled->set_border_color(disabled_color);
+	style_line_edit_disabled->set_bg_color(disabled_bg_color);
+
+	theme->set_stylebox("normal", "LineEdit", style_line_edit);
 	theme->set_stylebox("focus", "LineEdit", style_widget_focus);
-	theme->set_stylebox("read_only", "LineEdit", style_widget_disabled);
+	theme->set_stylebox("read_only", "LineEdit", style_line_edit_disabled);
 	theme->set_icon("clear", "LineEdit", theme->get_icon("GuiClose", "EditorIcons"));
 	theme->set_color("read_only", "LineEdit", font_disabled_color);
 	theme->set_color("font_color", "LineEdit", font_color);
@@ -969,9 +983,9 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_color("clear_button_color_pressed", "LineEdit", accent_color);
 
 	// TextEdit
-	theme->set_stylebox("normal", "TextEdit", style_widget);
-	theme->set_stylebox("focus", "TextEdit", style_widget_hover);
-	theme->set_stylebox("read_only", "TextEdit", style_widget_disabled);
+	theme->set_stylebox("normal", "TextEdit", style_line_edit);
+	theme->set_stylebox("focus", "TextEdit", style_widget_focus);
+	theme->set_stylebox("read_only", "TextEdit", style_line_edit_disabled);
 	theme->set_constant("side_margin", "TabContainer", 0);
 	theme->set_icon("tab", "TextEdit", theme->get_icon("GuiTab", "EditorIcons"));
 	theme->set_icon("space", "TextEdit", theme->get_icon("GuiSpace", "EditorIcons"));
@@ -1014,14 +1028,22 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_constant("hseparation", "GridContainer", default_margin_size * EDSCALE);
 	theme->set_constant("vseparation", "GridContainer", default_margin_size * EDSCALE);
 
-	// WindowDialog
+	// Window
+
+	// Prevent corner artifacts between window title and body.
+	Ref<StyleBoxFlat> style_window_title = style_default->duplicate();
+	style_window_title->set_corner_radius(CORNER_TOP_LEFT, 0);
+	style_window_title->set_corner_radius(CORNER_TOP_RIGHT, 0);
+	// Prevent visible line between window title and body.
+	style_window_title->set_expand_margin_size(SIDE_BOTTOM, 2 * EDSCALE);
+	theme->set_stylebox("panel", "Window", style_window_title);
+
 	Ref<StyleBoxFlat> style_window = style_popup->duplicate();
-	style_window->set_border_color(tab_color);
+	style_window->set_border_color(base_color);
 	style_window->set_border_width(SIDE_TOP, 24 * EDSCALE);
 	style_window->set_expand_margin_size(SIDE_TOP, 24 * EDSCALE);
-
-	theme->set_stylebox("panel", "Window", style_default);
 	theme->set_stylebox("panel_window", "Window", style_window);
+
 	theme->set_color("title_color", "Window", font_color);
 	theme->set_icon("close", "Window", theme->get_icon("GuiClose", "EditorIcons"));
 	theme->set_icon("close_highlight", "Window", theme->get_icon("GuiClose", "EditorIcons"));
@@ -1032,10 +1054,10 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_font("title_font", "Window", theme->get_font("title", "EditorFonts"));
 	theme->set_font_size("title_font_size", "Window", theme->get_font_size("title_size", "EditorFonts"));
 
-	// complex window, for now only Editor settings and Project settings
+	// Complex window (currently only Editor Settings and Project Settings)
 	Ref<StyleBoxFlat> style_complex_window = style_window->duplicate();
 	style_complex_window->set_bg_color(dark_color_2);
-	style_complex_window->set_border_color(highlight_tabs ? tab_color : dark_color_2);
+	style_complex_window->set_border_color(dark_color_2);
 	theme->set_stylebox("panel", "EditorSettingsDialog", style_complex_window);
 	theme->set_stylebox("panel", "ProjectSettingsEditor", style_complex_window);
 	theme->set_stylebox("panel", "EditorAbout", style_complex_window);
@@ -1069,18 +1091,18 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	// HSlider
 	theme->set_icon("grabber_highlight", "HSlider", theme->get_icon("GuiSliderGrabberHl", "EditorIcons"));
 	theme->set_icon("grabber", "HSlider", theme->get_icon("GuiSliderGrabber", "EditorIcons"));
-	theme->set_stylebox("slider", "HSlider", make_flat_stylebox(dark_color_3, 0, default_margin_size / 2, 0, default_margin_size / 2));
-	theme->set_stylebox("grabber_area", "HSlider", make_flat_stylebox(contrast_color_1, 0, default_margin_size / 2, 0, default_margin_size / 2));
+	theme->set_stylebox("slider", "HSlider", make_flat_stylebox(dark_color_3, 0, default_margin_size / 2, 0, default_margin_size / 2, corner_width));
+	theme->set_stylebox("grabber_area", "HSlider", make_flat_stylebox(contrast_color_1, 0, default_margin_size / 2, 0, default_margin_size / 2, corner_width));
 	theme->set_stylebox("grabber_area_highlight", "HSlider", make_flat_stylebox(contrast_color_1, 0, default_margin_size / 2, 0, default_margin_size / 2));
 
 	// VSlider
 	theme->set_icon("grabber", "VSlider", theme->get_icon("GuiSliderGrabber", "EditorIcons"));
 	theme->set_icon("grabber_highlight", "VSlider", theme->get_icon("GuiSliderGrabberHl", "EditorIcons"));
-	theme->set_stylebox("slider", "VSlider", make_flat_stylebox(dark_color_3, default_margin_size / 2, 0, default_margin_size / 2, 0));
-	theme->set_stylebox("grabber_area", "VSlider", make_flat_stylebox(contrast_color_1, default_margin_size / 2, 0, default_margin_size / 2, 0));
+	theme->set_stylebox("slider", "VSlider", make_flat_stylebox(dark_color_3, default_margin_size / 2, 0, default_margin_size / 2, 0, corner_width));
+	theme->set_stylebox("grabber_area", "VSlider", make_flat_stylebox(contrast_color_1, default_margin_size / 2, 0, default_margin_size / 2, 0, corner_width));
 	theme->set_stylebox("grabber_area_highlight", "VSlider", make_flat_stylebox(contrast_color_1, default_margin_size / 2, 0, default_margin_size / 2, 0));
 
-	//RichTextLabel
+	// RichTextLabel
 	theme->set_color("default_color", "RichTextLabel", font_color);
 	theme->set_color("font_shadow_color", "RichTextLabel", Color(0, 0, 0, 0));
 	theme->set_constant("shadow_offset_x", "RichTextLabel", 1 * EDSCALE);
@@ -1092,7 +1114,7 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_color("headline_color", "EditorHelp", mono_color);
 
 	// Panel
-	theme->set_stylebox("panel", "Panel", make_flat_stylebox(dark_color_1, 6, 4, 6, 4));
+	theme->set_stylebox("panel", "Panel", make_flat_stylebox(dark_color_1, 6, 4, 6, 4, corner_width));
 	theme->set_stylebox("panel_fg", "Panel", style_default);
 
 	// Label
@@ -1113,16 +1135,15 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 
 	// TooltipPanel
 	Ref<StyleBoxFlat> style_tooltip = style_popup->duplicate();
-	float v = MAX(border_size * EDSCALE, 1.0);
-	style_tooltip->set_default_margin(SIDE_LEFT, v);
-	style_tooltip->set_default_margin(SIDE_TOP, v);
-	style_tooltip->set_default_margin(SIDE_RIGHT, v);
-	style_tooltip->set_default_margin(SIDE_BOTTOM, v);
-	style_tooltip->set_bg_color(Color(mono_color.r, mono_color.g, mono_color.b, 0.9));
-	style_tooltip->set_border_width_all(border_width);
-	style_tooltip->set_border_color(mono_color);
-	theme->set_color("font_color", "TooltipLabel", font_color.inverted());
-	theme->set_color("font_shadow_color", "TooltipLabel", mono_color.inverted() * Color(1, 1, 1, 0.1));
+	style_tooltip->set_shadow_size(0);
+	style_tooltip->set_default_margin(SIDE_LEFT, default_margin_size * EDSCALE);
+	style_tooltip->set_default_margin(SIDE_TOP, default_margin_size * EDSCALE * 0.5);
+	style_tooltip->set_default_margin(SIDE_RIGHT, default_margin_size * EDSCALE);
+	style_tooltip->set_default_margin(SIDE_BOTTOM, default_margin_size * EDSCALE * 0.5);
+	style_tooltip->set_bg_color(mono_color.inverted() * Color(1, 1, 1, 0.8));
+	style_tooltip->set_border_width_all(0);
+	theme->set_color("font_color", "TooltipLabel", font_hover_color);
+	theme->set_color("font_color_shadow", "TooltipLabel", Color(0, 0, 0, 0));
 	theme->set_stylebox("panel", "TooltipPanel", style_tooltip);
 
 	// PopupPanel
@@ -1189,23 +1210,20 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_color("resizer_color", "GraphEditMinimap", minimap_resizer_color);
 
 	// GraphNode
-	const float mv = dark_theme ? 0.0 : 1.0;
-	const float mv2 = 1.0 - mv;
 	const int gn_margin_side = 28;
-	Ref<StyleBoxFlat> graphsb = make_flat_stylebox(Color(mv, mv, mv, 0.7), gn_margin_side, 24, gn_margin_side, 5);
+
+	Ref<StyleBoxFlat> graphsb = make_flat_stylebox(dark_color_3 * Color(1, 1, 1, 0.7), gn_margin_side, 24, gn_margin_side, 5, corner_width);
 	graphsb->set_border_width_all(border_width);
-	graphsb->set_border_color(Color(mv2, mv2, mv2, 0.9));
-	Ref<StyleBoxFlat> graphsbselected = make_flat_stylebox(Color(mv, mv, mv, 0.9), gn_margin_side, 24, gn_margin_side, 5);
-	graphsbselected->set_border_width_all(border_width);
+	graphsb->set_border_color(dark_color_3);
+	Ref<StyleBoxFlat> graphsbselected = make_flat_stylebox(dark_color_3 * Color(1, 1, 1, 0.9), gn_margin_side, 24, gn_margin_side, 5, corner_width);
+	graphsbselected->set_border_width_all(2 * EDSCALE + border_width);
 	graphsbselected->set_border_color(Color(accent_color.r, accent_color.g, accent_color.b, 0.9));
-	graphsbselected->set_shadow_size(8 * EDSCALE);
-	graphsbselected->set_shadow_color(shadow_color);
-	Ref<StyleBoxFlat> graphsbcomment = make_flat_stylebox(Color(mv, mv, mv, 0.3), gn_margin_side, 24, gn_margin_side, 5);
+	Ref<StyleBoxFlat> graphsbcomment = make_flat_stylebox(dark_color_3 * Color(1, 1, 1, 0.3), gn_margin_side, 24, gn_margin_side, 5, corner_width);
 	graphsbcomment->set_border_width_all(border_width);
-	graphsbcomment->set_border_color(Color(mv2, mv2, mv2, 0.9));
-	Ref<StyleBoxFlat> graphsbcommentselected = make_flat_stylebox(Color(mv, mv, mv, 0.4), gn_margin_side, 24, gn_margin_side, 5);
+	graphsbcomment->set_border_color(dark_color_3);
+	Ref<StyleBoxFlat> graphsbcommentselected = make_flat_stylebox(dark_color_3 * Color(1, 1, 1, 0.4), gn_margin_side, 24, gn_margin_side, 5, corner_width);
 	graphsbcommentselected->set_border_width_all(border_width);
-	graphsbcommentselected->set_border_color(Color(mv2, mv2, mv2, 0.9));
+	graphsbcommentselected->set_border_color(dark_color_3);
 	Ref<StyleBoxFlat> graphsbbreakpoint = graphsbselected->duplicate();
 	graphsbbreakpoint->set_draw_center(false);
 	graphsbbreakpoint->set_border_color(warning_color);
@@ -1214,21 +1232,19 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	graphsbposition->set_draw_center(false);
 	graphsbposition->set_border_color(error_color);
 	graphsbposition->set_shadow_color(error_color * Color(1.0, 1.0, 1.0, 0.2));
-	Ref<StyleBoxFlat> smgraphsb = make_flat_stylebox(Color(mv, mv, mv, 0.7), gn_margin_side, 24, gn_margin_side, 5);
+	Ref<StyleBoxFlat> smgraphsb = make_flat_stylebox(dark_color_3 * Color(1, 1, 1, 0.7), gn_margin_side, 24, gn_margin_side, 5, corner_width);
 	smgraphsb->set_border_width_all(border_width);
-	smgraphsb->set_border_color(Color(mv2, mv2, mv2, 0.9));
-	Ref<StyleBoxFlat> smgraphsbselected = make_flat_stylebox(Color(mv, mv, mv, 0.9), gn_margin_side, 24, gn_margin_side, 5);
-	smgraphsbselected->set_border_width_all(border_width);
+	smgraphsb->set_border_color(dark_color_3);
+	Ref<StyleBoxFlat> smgraphsbselected = make_flat_stylebox(dark_color_3 * Color(1, 1, 1, 0.9), gn_margin_side, 24, gn_margin_side, 5, corner_width);
+	smgraphsbselected->set_border_width_all(2 * EDSCALE + border_width);
 	smgraphsbselected->set_border_color(Color(accent_color.r, accent_color.g, accent_color.b, 0.9));
 	smgraphsbselected->set_shadow_size(8 * EDSCALE);
 	smgraphsbselected->set_shadow_color(shadow_color);
 
-	if (use_gn_headers) {
-		graphsb->set_border_width(SIDE_TOP, 24 * EDSCALE);
-		graphsbselected->set_border_width(SIDE_TOP, 24 * EDSCALE);
-		graphsbcomment->set_border_width(SIDE_TOP, 24 * EDSCALE);
-		graphsbcommentselected->set_border_width(SIDE_TOP, 24 * EDSCALE);
-	}
+	graphsb->set_border_width(SIDE_TOP, 24 * EDSCALE);
+	graphsbselected->set_border_width(SIDE_TOP, 24 * EDSCALE);
+	graphsbcomment->set_border_width(SIDE_TOP, 24 * EDSCALE);
+	graphsbcommentselected->set_border_width(SIDE_TOP, 24 * EDSCALE);
 
 	theme->set_stylebox("frame", "GraphNode", graphsb);
 	theme->set_stylebox("selectedframe", "GraphNode", graphsbselected);
@@ -1239,7 +1255,7 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_stylebox("state_machine_frame", "GraphNode", smgraphsb);
 	theme->set_stylebox("state_machine_selectedframe", "GraphNode", smgraphsbselected);
 
-	Color default_node_color = Color(mv2, mv2, mv2);
+	Color default_node_color = dark_color_1.inverted();
 	theme->set_color("title_color", "GraphNode", default_node_color);
 	default_node_color.a = 0.7;
 	theme->set_color("close_color", "GraphNode", default_node_color);
@@ -1257,7 +1273,7 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_icon("port", "GraphNode", theme->get_icon("GuiGraphNodePort", "EditorIcons"));
 
 	// GridContainer
-	theme->set_constant("vseparation", "GridContainer", (extra_spacing + default_margin_size) * EDSCALE);
+	theme->set_constant("vseparation", "GridContainer", Math::round(widget_default_margin.y - 2 * EDSCALE));
 
 	// FileDialog
 	theme->set_icon("folder", "FileDialog", theme->get_icon("Folder", "EditorIcons"));
diff --git a/editor/filesystem_dock.cpp b/editor/filesystem_dock.cpp
index 899070f036..0c3bdfb3a3 100644
--- a/editor/filesystem_dock.cpp
+++ b/editor/filesystem_dock.cpp
@@ -2802,7 +2802,6 @@ FileSystemDock::FileSystemDock(EditorNode *p_editor) {
 	toolbar_hbc->add_child(current_path);
 
 	button_reload = memnew(Button);
-	button_reload->set_flat(true);
 	button_reload->connect("pressed", callable_mp(this, &FileSystemDock::_rescan));
 	button_reload->set_focus_mode(FOCUS_NONE);
 	button_reload->set_tooltip(TTR("Re-Scan Filesystem"));
@@ -2810,7 +2809,6 @@ FileSystemDock::FileSystemDock(EditorNode *p_editor) {
 	toolbar_hbc->add_child(button_reload);
 
 	button_toggle_display_mode = memnew(Button);
-	button_toggle_display_mode->set_flat(true);
 	button_toggle_display_mode->set_toggle_mode(true);
 	button_toggle_display_mode->connect("toggled", callable_mp(this, &FileSystemDock::_toggle_split_mode));
 	button_toggle_display_mode->set_focus_mode(FOCUS_NONE);
diff --git a/editor/inspector_dock.cpp b/editor/inspector_dock.cpp
index fbcd76a95f..6265dfc2e4 100644
--- a/editor/inspector_dock.cpp
+++ b/editor/inspector_dock.cpp
@@ -535,7 +535,6 @@ InspectorDock::InspectorDock(EditorNode *p_editor, EditorData &p_editor_data) {
 	} else {
 		backward_button->set_icon(get_theme_icon("Back", "EditorIcons"));
 	}
-	backward_button->set_flat(true);
 	backward_button->set_tooltip(TTR("Go to the previous edited object in history."));
 	backward_button->set_disabled(true);
 	backward_button->connect("pressed", callable_mp(this, &InspectorDock::_edit_back));
@@ -548,7 +547,6 @@ InspectorDock::InspectorDock(EditorNode *p_editor, EditorData &p_editor_data) {
 	} else {
 		forward_button->set_icon(get_theme_icon("Forward", "EditorIcons"));
 	}
-	forward_button->set_flat(true);
 	forward_button->set_tooltip(TTR("Go to the next edited object in history."));
 	forward_button->set_disabled(true);
 	forward_button->connect("pressed", callable_mp(this, &InspectorDock::_edit_forward));
diff --git a/editor/plugins/animation_blend_tree_editor_plugin.cpp b/editor/plugins/animation_blend_tree_editor_plugin.cpp
index 48fb507bb1..78c30df04b 100644
--- a/editor/plugins/animation_blend_tree_editor_plugin.cpp
+++ b/editor/plugins/animation_blend_tree_editor_plugin.cpp
@@ -231,18 +231,16 @@ void AnimationNodeBlendTreeEditor::_update_graph() {
 			mb->get_popup()->connect("index_pressed", callable_mp(this, &AnimationNodeBlendTreeEditor::_anim_selected), varray(options, E->get()), CONNECT_DEFERRED);
 		}
 
-		if (EditorSettings::get_singleton()->get("interface/theme/use_graph_node_headers")) {
-			Ref<StyleBoxFlat> sb = node->get_theme_stylebox("frame", "GraphNode");
-			Color c = sb->get_border_color();
-			Color mono_color = ((c.r + c.g + c.b) / 3) < 0.7 ? Color(1.0, 1.0, 1.0) : Color(0.0, 0.0, 0.0);
-			mono_color.a = 0.85;
-			c = mono_color;
-
-			node->add_theme_color_override("title_color", c);
-			c.a = 0.7;
-			node->add_theme_color_override("close_color", c);
-			node->add_theme_color_override("resizer_color", c);
-		}
+		Ref<StyleBoxFlat> sb = node->get_theme_stylebox("frame", "GraphNode");
+		Color c = sb->get_border_color();
+		Color mono_color = ((c.r + c.g + c.b) / 3) < 0.7 ? Color(1.0, 1.0, 1.0) : Color(0.0, 0.0, 0.0);
+		mono_color.a = 0.85;
+		c = mono_color;
+
+		node->add_theme_color_override("title_color", c);
+		c.a = 0.7;
+		node->add_theme_color_override("close_color", c);
+		node->add_theme_color_override("resizer_color", c);
 	}
 
 	List<AnimationNodeBlendTree::NodeConnection> connections;
diff --git a/editor/plugins/asset_library_editor_plugin.cpp b/editor/plugins/asset_library_editor_plugin.cpp
index fd47d9964e..a0d9afee74 100644
--- a/editor/plugins/asset_library_editor_plugin.cpp
+++ b/editor/plugins/asset_library_editor_plugin.cpp
@@ -240,7 +240,6 @@ void EditorAssetLibraryItemDescription::add_preview(int p_id, bool p_video, cons
 	preview.video_link = p_url;
 	preview.is_video = p_video;
 	preview.button = memnew(Button);
-	preview.button->set_flat(true);
 	preview.button->set_icon(previews->get_theme_icon("ThumbnailWait", "EditorIcons"));
 	preview.button->set_toggle_mode(true);
 	preview.button->connect("pressed", callable_mp(this, &EditorAssetLibraryItemDescription::_preview_click), varray(p_id));
diff --git a/editor/plugins/canvas_item_editor_plugin.cpp b/editor/plugins/canvas_item_editor_plugin.cpp
index fc3e15aa52..bf1d87cada 100644
--- a/editor/plugins/canvas_item_editor_plugin.cpp
+++ b/editor/plugins/canvas_item_editor_plugin.cpp
@@ -5853,6 +5853,13 @@ CanvasItemEditor::CanvasItemEditor(EditorNode *p_editor) {
 
 	updating_scroll = false;
 
+	// Add some margin to the left for better aesthetics.
+	// This prevents the first button's hover/pressed effect from "touching" the panel's border,
+	// which looks ugly.
+	Control *margin_left = memnew(Control);
+	hb->add_child(margin_left);
+	margin_left->set_custom_minimum_size(Size2(2, 0) * EDSCALE);
+
 	select_button = memnew(Button);
 	select_button->set_flat(true);
 	hb->add_child(select_button);
@@ -6089,7 +6096,6 @@ CanvasItemEditor::CanvasItemEditor(EditorNode *p_editor) {
 
 	key_loc_button = memnew(Button);
 	key_loc_button->set_toggle_mode(true);
-	key_loc_button->set_flat(true);
 	key_loc_button->set_pressed(true);
 	key_loc_button->set_focus_mode(FOCUS_NONE);
 	key_loc_button->connect("pressed", callable_mp(this, &CanvasItemEditor::_popup_callback), varray(ANIM_INSERT_POS));
@@ -6098,7 +6104,6 @@ CanvasItemEditor::CanvasItemEditor(EditorNode *p_editor) {
 
 	key_rot_button = memnew(Button);
 	key_rot_button->set_toggle_mode(true);
-	key_rot_button->set_flat(true);
 	key_rot_button->set_pressed(true);
 	key_rot_button->set_focus_mode(FOCUS_NONE);
 	key_rot_button->connect("pressed", callable_mp(this, &CanvasItemEditor::_popup_callback), varray(ANIM_INSERT_ROT));
@@ -6107,14 +6112,12 @@ CanvasItemEditor::CanvasItemEditor(EditorNode *p_editor) {
 
 	key_scale_button = memnew(Button);
 	key_scale_button->set_toggle_mode(true);
-	key_scale_button->set_flat(true);
 	key_scale_button->set_focus_mode(FOCUS_NONE);
 	key_scale_button->connect("pressed", callable_mp(this, &CanvasItemEditor::_popup_callback), varray(ANIM_INSERT_SCALE));
 	key_scale_button->set_tooltip(TTR("Scale mask for inserting keys."));
 	animation_hb->add_child(key_scale_button);
 
 	key_insert_button = memnew(Button);
-	key_insert_button->set_flat(true);
 	key_insert_button->set_focus_mode(FOCUS_NONE);
 	key_insert_button->connect("pressed", callable_mp(this, &CanvasItemEditor::_popup_callback), varray(ANIM_INSERT_KEY));
 	key_insert_button->set_tooltip(TTR("Insert keys (based on mask)."));
diff --git a/editor/plugins/node_3d_editor_plugin.cpp b/editor/plugins/node_3d_editor_plugin.cpp
index 023d91be30..81f1852fba 100644
--- a/editor/plugins/node_3d_editor_plugin.cpp
+++ b/editor/plugins/node_3d_editor_plugin.cpp
@@ -6692,6 +6692,13 @@ Node3DEditor::Node3DEditor(EditorNode *p_editor) {
 	button_binds.resize(1);
 	String sct;
 
+	// Add some margin to the left for better aesthetics.
+	// This prevents the first button's hover/pressed effect from "touching" the panel's border,
+	// which looks ugly.
+	Control *margin_left = memnew(Control);
+	hbc_menu->add_child(margin_left);
+	margin_left->set_custom_minimum_size(Size2(2, 0) * EDSCALE);
+
 	tool_button[TOOL_MODE_SELECT] = memnew(Button);
 	hbc_menu->add_child(tool_button[TOOL_MODE_SELECT]);
 	tool_button[TOOL_MODE_SELECT]->set_toggle_mode(true);
diff --git a/editor/plugins/root_motion_editor_plugin.cpp b/editor/plugins/root_motion_editor_plugin.cpp
index 50f4d8493f..1e6237ced1 100644
--- a/editor/plugins/root_motion_editor_plugin.cpp
+++ b/editor/plugins/root_motion_editor_plugin.cpp
@@ -205,7 +205,6 @@ void EditorPropertyRootMotion::update_property() {
 		assign->set_flat(false);
 		return;
 	}
-	assign->set_flat(true);
 
 	Node *base_node = nullptr;
 	if (base_hint != NodePath()) {
@@ -247,14 +246,12 @@ EditorPropertyRootMotion::EditorPropertyRootMotion() {
 	HBoxContainer *hbc = memnew(HBoxContainer);
 	add_child(hbc);
 	assign = memnew(Button);
-	assign->set_flat(true);
 	assign->set_h_size_flags(SIZE_EXPAND_FILL);
 	assign->set_clip_text(true);
 	assign->connect("pressed", callable_mp(this, &EditorPropertyRootMotion::_node_assign));
 	hbc->add_child(assign);
 
 	clear = memnew(Button);
-	clear->set_flat(true);
 	clear->connect("pressed", callable_mp(this, &EditorPropertyRootMotion::_node_clear));
 	hbc->add_child(clear);
 
diff --git a/editor/plugins/script_editor_plugin.cpp b/editor/plugins/script_editor_plugin.cpp
index 58e6717a3d..9a00d68447 100644
--- a/editor/plugins/script_editor_plugin.cpp
+++ b/editor/plugins/script_editor_plugin.cpp
@@ -1827,7 +1827,6 @@ void ScriptEditor::_update_help_overview() {
 
 void ScriptEditor::_update_script_colors() {
 	bool script_temperature_enabled = EditorSettings::get_singleton()->get("text_editor/script_list/script_temperature_enabled");
-	bool highlight_current = EditorSettings::get_singleton()->get("text_editor/script_list/highlight_current_script");
 
 	int hist_size = EditorSettings::get_singleton()->get("text_editor/script_list/script_temperature_history_size");
 	Color hot_color = get_theme_color("accent_color", "Editor");
@@ -1842,11 +1841,7 @@ void ScriptEditor::_update_script_colors() {
 
 		script_list->set_item_custom_bg_color(i, Color(0, 0, 0, 0));
 
-		bool current = tab_container->get_current_tab() == c;
-		if (current && highlight_current) {
-			script_list->set_item_custom_bg_color(i, EditorSettings::get_singleton()->get("text_editor/script_list/current_script_background_color"));
-
-		} else if (script_temperature_enabled) {
+		if (script_temperature_enabled) {
 			if (!n->has_meta("__editor_pass")) {
 				continue;
 			}
@@ -3672,9 +3667,7 @@ ScriptEditorPlugin::ScriptEditorPlugin(EditorNode *p_node) {
 	EDITOR_DEF("text_editor/external/use_external_editor", false);
 	EDITOR_DEF("text_editor/external/exec_path", "");
 	EDITOR_DEF("text_editor/script_list/script_temperature_enabled", true);
-	EDITOR_DEF("text_editor/script_list/highlight_current_script", true);
 	EDITOR_DEF("text_editor/script_list/script_temperature_history_size", 15);
-	EDITOR_DEF("text_editor/script_list/current_script_background_color", Color(1, 1, 1, 0.3));
 	EDITOR_DEF("text_editor/script_list/group_help_pages", true);
 	EditorSettings::get_singleton()->add_property_hint(PropertyInfo(Variant::INT, "text_editor/script_list/sort_scripts_by", PROPERTY_HINT_ENUM, "Name,Path,None"));
 	EDITOR_DEF("text_editor/script_list/sort_scripts_by", 0);
diff --git a/editor/plugins/visual_shader_editor_plugin.cpp b/editor/plugins/visual_shader_editor_plugin.cpp
index acc77bd098..7d5e72ff8e 100644
--- a/editor/plugins/visual_shader_editor_plugin.cpp
+++ b/editor/plugins/visual_shader_editor_plugin.cpp
@@ -1175,26 +1175,15 @@ void VisualShaderEditor::_draw_color_over_button(Object *obj, Color p_color) {
 }
 
 void VisualShaderEditor::_update_created_node(GraphNode *node) {
-	if (EditorSettings::get_singleton()->get("interface/theme/use_graph_node_headers")) {
-		Ref<StyleBoxFlat> sb = node->get_theme_stylebox("frame", "GraphNode");
-		Color c = sb->get_border_color();
-		Color ic;
-		Color mono_color;
-		if (((c.r + c.g + c.b) / 3) < 0.7) {
-			mono_color = Color(1.0, 1.0, 1.0);
-			ic = Color(0.0, 0.0, 0.0, 0.7);
-		} else {
-			mono_color = Color(0.0, 0.0, 0.0);
-			ic = Color(1.0, 1.0, 1.0, 0.7);
-		}
-		mono_color.a = 0.85;
-		c = mono_color;
-
-		node->add_theme_color_override("title_color", c);
-		c.a = 0.7;
-		node->add_theme_color_override("close_color", c);
-		node->add_theme_color_override("resizer_color", ic);
-	}
+	const Ref<StyleBoxFlat> sb = node->get_theme_stylebox("frame", "GraphNode");
+	Color c = sb->get_border_color();
+	const Color mono_color = ((c.r + c.g + c.b) / 3) < 0.7 ? Color(1.0, 1.0, 1.0, 0.85) : Color(0.0, 0.0, 0.0, 0.85);
+	c = mono_color;
+
+	node->add_theme_color_override("title_color", c);
+	c.a = 0.7;
+	node->add_theme_color_override("close_color", c);
+	node->add_theme_color_override("resizer_color", c);
 }
 
 void VisualShaderEditor::_update_uniforms(bool p_update_refs) {
diff --git a/editor/property_editor.cpp b/editor/property_editor.cpp
index 1a010b9168..8b0d9ae0fc 100644
--- a/editor/property_editor.cpp
+++ b/editor/property_editor.cpp
@@ -1823,7 +1823,6 @@ CustomPropertyEditor::CustomPropertyEditor() {
 		Vector<Variant> binds;
 		binds.push_back(i);
 		action_buttons[i]->connect("pressed", callable_mp(this, &CustomPropertyEditor::_action_pressed), binds);
-		action_buttons[i]->set_flat(true);
 	}
 
 	color_picker = nullptr;
diff --git a/editor/script_create_dialog.cpp b/editor/script_create_dialog.cpp
index f3addd8904..c2bfdaae96 100644
--- a/editor/script_create_dialog.cpp
+++ b/editor/script_create_dialog.cpp
@@ -838,7 +838,6 @@ ScriptCreateDialog::ScriptCreateDialog() {
 	parent_search_button->connect("pressed", callable_mp(this, &ScriptCreateDialog::_browse_class_in_tree));
 	hb->add_child(parent_search_button);
 	parent_browse_button = memnew(Button);
-	parent_browse_button->set_flat(true);
 	parent_browse_button->connect("pressed", callable_mp(this, &ScriptCreateDialog::_browse_path), varray(true, false));
 	hb->add_child(parent_browse_button);
 	gc->add_child(memnew(Label(TTR("Inherits:"))));
@@ -877,7 +876,6 @@ ScriptCreateDialog::ScriptCreateDialog() {
 	file_path->set_h_size_flags(Control::SIZE_EXPAND_FILL);
 	hb->add_child(file_path);
 	path_button = memnew(Button);
-	path_button->set_flat(true);
 	path_button->connect("pressed", callable_mp(this, &ScriptCreateDialog::_browse_path), varray(false, true));
 	hb->add_child(path_button);
 	gc->add_child(memnew(Label(TTR("Path:"))));