enhance: use font awesome copy icon and high-contrast setting for all themes

Author: zouyu4524

_includes/scripts/lib/copy-to-clipboard.js

@@ -2,7 +2,7 @@
 	var snippets = document.querySelectorAll('pre');
 	[].forEach.call(snippets, function(snippet) {
 		if (snippet.closest('.snippet') !== null) {
-			snippet.firstChild.insertAdjacentHTML('beforebegin', '<button class="btn" data-clipboard-snippet><img class="clippy" height="20" src="/assets/clippy.svg" alt="Copy to clipboard"></button>');
+			snippet.firstChild.insertAdjacentHTML('beforebegin', '<button class="btn" data-clipboard-snippet><i class="far fa-copy"></i></button>');
 		}
 	});
 	var clipboardSnippets = new ClipboardJS('[data-clipboard-snippet]', {

_sass/additional/_copy-to-clipboard.scss

@@ -61,13 +61,13 @@
 	transform: translateX(50%)
 }
 
-.clippy {
+.fa-copy {
 	margin-top: -3px;
 	position: relative;
 	top: 3px
 }
 
-.btn[disabled] .clippy {
+.btn[disabled] .fa-copy {
 	opacity: .3
 }
 
@@ -84,7 +84,8 @@
 	padding: 2px 6px;
 	position: absolute;
 	right: 4px;
-	top: 4px
+	top: 4px;
+	color: $copy-button-color
 }
 
 .snippet:hover .btn, .snippet .btn:focus {

_sass/skins/highlight/_default.scss

@@ -0,0 +1,2 @@
+// copy button color
+$copy-button-color: #000;

_sass/skins/highlight/_tomorrow-night-blue.scss

@@ -1,2 +1,5 @@
 @import "./tomorrow/night-blue";
 @import "./tomorrow/highlight";
+
+// copy button color
+$copy-button-color: #fff;

_sass/skins/highlight/_tomorrow-night-bright.scss

@@ -1,2 +1,5 @@
 @import "./tomorrow/night-bright";
 @import "./tomorrow/highlight";
+
+// copy button color
+$copy-button-color: #fff;

_sass/skins/highlight/_tomorrow-night-eighties.scss

@@ -1,2 +1,5 @@
 @import "./tomorrow/night-eighties";
 @import "./tomorrow/highlight";
+
+// copy button color
+$copy-button-color: #fff;

_sass/skins/highlight/_tomorrow-night.scss

@@ -1,2 +1,5 @@
 @import "./tomorrow/night";
 @import "./tomorrow/highlight";
+
+// copy button color
+$copy-button-color: #fff;

_sass/skins/highlight/_tomorrow.scss

@@ -1,2 +1,5 @@
 @import "./tomorrow/default";
 @import "./tomorrow/highlight";
+
+// copy button color
+$copy-button-color: #000;