feat: support mermaid

feat: codeblock highlight

feat: dark mode for highlight

feat: copy button for code block

feat: support katex math rendering

assets/js/code-copy.js

@@ -0,0 +1,24 @@
+document.querySelectorAll('.code-copy-btn').forEach(function (button) {
+  button.addEventListener('click', function (e) {
+    const targetId = e.target.getAttribute('data-clipboard-target');
+    const target = document.querySelector(targetId);
+    const codeElements = target.querySelectorAll('code');
+    // Select the last code element in case line numbers are present
+    const codeElement = codeElements[codeElements.length - 1];
+    if (codeElement) {
+      // Replace double newlines with single newlines in the innerText
+      // as each line inside <span> has trailing newline '\n'
+      const code = codeElement.innerText.replace(/\n\n/g, '\n');
+      navigator.clipboard.writeText(code).then(function () {
+        button.classList.add('copied');
+        setTimeout(function () {
+          button.classList.remove('copied');
+        }, 500);
+      }).catch(function (err) {
+        console.error('Failed to copy text: ', err);
+      });
+    } else {
+      console.error('Target element not found');
+    }
+  });
+});