perf(ui): improve web accessibility (#447)

- Make color and contrast meets WCAG 2 AA and above
- Fixes `aria-label` on button "copy link" in posts

_javascript/modules/components/clipboard.js

@@ -99,7 +99,9 @@ export function initClipboard() {
 
   /* --- Post link sharing --- */
 
-  $('#copy-link').on('click', (e) => {
+  const btnCopyLink = $('#copy-link');
+
+  btnCopyLink.on('click', (e) => {
     let target = $(e.target);
 
     if (isLocked(target)) {
@@ -120,4 +122,10 @@ export function initClipboard() {
       }, TIMEOUT);
     });
   });
+
+  btnCopyLink.on('mouseleave', function (e) {
+    const target = $(e.target);
+    target.tooltip('hide');
+    console.log('mouse leave...');
+  });
 }