Merge pull request #114 from ckeditor/t/ckeditor5-ui/144

Other: Migrated the theme from SASS to PostCSS (see ckeditor/ckeditor5-ui#144).

BREAKING CHANGE: The styles are no longer developed in SASS which means various `.scss` files (including variables, mixins, etc.) became unavailable. Please refer to the [Theme Customization](https://docs.ckeditor.com/ckeditor5/latest/framework/guides/ui/theme-customization.html) guide to learn more about migration to PostCSS.

docs/_snippets/examples/custom.css

@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2003-2017, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+:root {
+	/* Overrides the border-radius setting in the theme. */
+	--ck-border-radius: 4px;
+
+	/* Overrides the default font size in the theme. */
+	--ck-font-size-base: 14px;
+
+	/* Helper variables to avoid duplication in the colors. */
+	--ck-custom-background: #4A494B;
+	--ck-custom-foreground: #3a393d;
+	--ck-custom-border: #383738;
+	--ck-custom-white: #fff;
+
+	/* -- Overrides generic colors -------------------------------------------------------------- */
+
+	--ck-color-focus-border: #48a3f5;
+	--ck-color-text: #fafafa;
+	--ck-color-shadow-drop: rgba( 0, 0, 0, .2 );
+	--ck-color-shadow-inner: rgba( 0, 0, 0, .1 );
+
+	/* -- Overrides the default .ck-button class colors ----------------------------------------- */
+
+	--ck-color-button-default-background: var(--ck-custom-background);
+	--ck-color-button-default-border: var(--ck-custom-border);
+	--ck-color-button-default-focus-background: #434244;
+	--ck-color-button-default-focus-border: #323232;
+	--ck-color-button-default-active-background: #3f3e40;
+	--ck-color-button-default-active-border: #302f30;
+	--ck-color-button-default-active-shadow: #3b3a3c;
+	--ck-color-button-default-disabled-background: var(--ck-custom-background);
+	--ck-color-button-default-disabled-border: var(--ck-custom-border);
+
+	--ck-color-button-on-background: var(--ck-custom-foreground);
+	--ck-color-button-on-border: var(--ck-custom-border);
+	--ck-color-button-on-focus-background: #343337;
+	--ck-color-button-on-focus-border: #323232;
+	--ck-color-button-on-active-background: #313034;
+	--ck-color-button-on-active-border: #302f30;
+	--ck-color-button-on-active-shadow: #2e2e31;
+	--ck-color-button-on-disabled-background: var(--ck-custom-foreground);
+	--ck-color-button-on-disabled-border: var(--ck-custom-border);
+
+	--ck-color-button-action-background: #1ABC9C;
+	--ck-color-button-action-border: #49d2b7;
+	--ck-color-button-action-focus-background: #17a98c;
+	--ck-color-button-action-focus-border: #42bda5;
+	--ck-color-button-action-active-background: #16a085;
+	--ck-color-button-action-active-border: #3eb39c;
+	--ck-color-button-action-active-shadow: #15967d;
+	--ck-color-button-action-disabled-background: #1ABC9C;
+	--ck-color-button-action-disabled-border: #49d2b7;
+	--ck-color-button-action-text: var(--ck-custom-white);
+
+	/* -- Overrides the default .ck-dropdown class colors --------------------------------------- */
+
+	--ck-color-dropdown-panel-background: var(--ck-custom-background);
+	--ck-color-dropdown-panel-border: var(--ck-custom-foreground);
+	--ck-color-dropdown-symbol: #f1f1f1;
+
+	/* -- Overrides the default .ck-input class colors ------------------------------------------ */
+
+	--ck-color-input-background: var(--ck-custom-foreground);
+	--ck-color-input-border: #6b6970;
+	--ck-color-input-text: #fafafa;
+	--ck-color-input-disabled-background: #343337;
+	--ck-color-input-disabled-border: #605f65;
+	--ck-color-input-disabled-text: #757575;
+
+	/* -- Overrides the default .ck-list class colors ------------------------------------------- */
+
+	--ck-color-list-background: var(--ck-custom-background);
+	--ck-color-list-item-background-hover: var(--ck-custom-foreground);
+	--ck-color-list-item-background-active: #1A8BF1;
+	--ck-color-list-item-text-active: var(--ck-custom-white);
+
+	/* -- Overrides the default .ck-balloon-panel class colors ---------------------------------- */
+
+	--ck-color-panel-background: var(--ck-custom-background);
+	--ck-color-panel-border: var(--ck-custom-border);
+
+	/* -- Overrides the default .ck-toolbar class colors ---------------------------------------- */
+
+	--ck-color-toolbar-background: var(--ck-custom-foreground);
+	--ck-color-toolbar-border: var(--ck-custom-border);
+
+	/* -- Overrides the default .ck-tooltip class colors ---------------------------------------- */
+
+	--ck-color-tooltip-background: #212025;
+	--ck-color-tooltip-text: #eee;
+
+	/* -- Overrides the default colors used by the editor --------------------------------------- */
+
+	--ck-color-editor-border: var(--ck-custom-background);
+	--ck-color-editor-toolbar-background: var(--ck-custom-background);
+
+	--ck-color-editor-toolbar-button-on-background: #3c3c3c;
+	--ck-color-editor-toolbar-button-on-border: transparent;
+	--ck-color-editor-toolbar-button-on-focus-background: #353535;
+	--ck-color-editor-toolbar-button-on-focus-border: transparent;
+	--ck-color-editor-toolbar-button-on-active-background: #272727;
+	--ck-color-editor-toolbar-button-on-active-border: transparent;
+	--ck-color-editor-toolbar-button-on-active-shadow: #2d2d2d;
+	--ck-color-editor-toolbar-button-on-disabled-background: transparent;
+	--ck-color-editor-toolbar-button-on-disabled-border: transparent;
+
+	--ck-color-editor-dropdown-background: #535254;
+
+	/* -- Overrides the default colors used by ckeditor5-image package -------------------------- */
+
+	--ck-color-image-caption-background: #f7f7f7;
+	--ck-color-image-caption-text: #333;
+
+	/* -- Overrides the default colors used by ckeditor5-widget package ------------------------- */
+
+	--ck-color-widget-border-blurred: #ddd;
+	--ck-color-widget-border-hover: #FFD25C;
+	--ck-color-widget-editable-focused-background: var(--ck-custom-white);
+}

docs/_snippets/examples/extras.css

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2003-2017, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+/* Allow using Lark's ck-box-shadow() mixin. */
+@import '@ckeditor/ckeditor5-theme-lark/theme/mixins/_shadow.css';
+
+/* The shadow should be 10% brighter than the toolbar background. */
+:root {
+	--ck-shadow-color: #646265;
+}
+
+.ck-editor-toolbar {
+	& .ck-button.ck-dropdown__button {
+		/* Apply a dedicated inner box-shadow to the dropdown button. */
+		@mixin ck-box-shadow
+			0 0 0 1px var(--ck-shadow-color) inset,
+			0 0 5px var(--ck-shadow-color) inset;
+	}
+}

docs/_snippets/examples/theme-lark.js

@@ -5,11 +5,10 @@
 
 /* globals console, window, document */
 
-/* config { "sassImportPath": "./custom.scss" } */
-
 import ClassicEditor from '@ckeditor/ckeditor5-editor-classic/src/classiceditor';
 import ArticlePluginSet from '@ckeditor/ckeditor5-core/tests/_utils/articlepluginset';
-import './extras.scss';
+import './custom.css';
+import './extras.css';
 
 ClassicEditor
 	.create( document.querySelector( '#snippet-classic-editor' ), {