diff --git a/frontend/404.html b/frontend/404.html
index 381fa674..58740f67 100644
--- a/frontend/404.html
+++ b/frontend/404.html
@@ -4,14 +4,14 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>404 — Not Found | CodePVG</title>
-    <link rel="icon" type="image/png" href="assets/logo.png" />
+    <link rel="icon" type="image/png" href="/assets/logo.png" />
     <link rel="preconnect" href="https://fonts.googleapis.com" />
     <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />
     <link
       href="https://fonts.googleapis.com/css2?family=Fira+Code:wght@400;500;600;700&family=Space+Mono:wght@400;700&family=Share+Tech+Mono&display=swap"
       rel="stylesheet"
     />
-    <link rel="stylesheet" href="styles/main.css" />
+    <link rel="stylesheet" href="/styles/main.css" />
     <style>
       /* 404-specific overrides */
       body {
@@ -26,17 +26,6 @@
         position: relative;
       }
 
-      /* Matrix rain canvas */
-      #matrix {
-        position: fixed;
-        top: 0;
-        left: 0;
-        width: 100%;
-        height: 100%;
-        z-index: 0;
-        opacity: 0.18;
-      }
-
       /* Main panel */
       .panel {
         position: relative;
@@ -159,11 +148,20 @@
         pointer-events: none;
         z-index: 2;
       }
+
+      @media (max-width: 768px) {
+        .panel {
+          padding: 2rem 2rem;
+          max-width: 90%;
+        }
+      }
+
       @media (max-width: 480px) {
         .panel {
           padding: 1.5rem 1.2rem;
           width: 95%;
         }
+
         .title {
           font-size: 1.6rem;
         }
@@ -171,17 +169,22 @@
         .subtitle {
           font-size: 0.75rem;
         }
+
         .line {
           font-size: 0.82rem;
           line-height: 1.6;
         }
+
         .nav-links {
           flex-direction: column;
+          align-items: center;
           gap: 0.75rem;
         }
+
         .nav-links a {
           text-align: center;
           width: 100%;
+          max-width: 280px;
           box-sizing: border-box;
         }
       }
@@ -189,7 +192,7 @@
   </head>
 
   <body>
-    <canvas id="matrix"></canvas>
+    <canvas id="matrix-canvas"></canvas>
 
     <div class="panel">
       <div class="title">404 — Not Found</div>
@@ -262,50 +265,7 @@
       </div>
     </div>
 
-    <script>
-      // Inject actual bad path
-      const p = window.location.pathname;
-      document.getElementById("cd-line").textContent = " cd " + p;
-      document.getElementById("path-display").textContent = p;
-
-      // Matrix rain
-      const canvas = document.getElementById("matrix");
-      const ctx = canvas.getContext("2d");
-
-      function resize() {
-        canvas.width = window.innerWidth;
-        canvas.height = window.innerHeight;
-      }
-      resize();
-      window.addEventListener("resize", resize);
-
-      const chars =
-        "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789@#$%^&*()アイウエオカキクケコサシスセソタチツテトナニヌネノ";
-      const fontSize = 14;
-      let cols = Math.floor(canvas.width / fontSize);
-      let drops = Array(cols).fill(1);
-
-      function drawMatrix() {
-        ctx.fillStyle = "rgba(0, 0, 0, 0.05)";
-        ctx.fillRect(0, 0, canvas.width, canvas.height);
-
-        ctx.fillStyle = "#00ff41";
-        ctx.font = fontSize + "px Share Tech Mono, monospace";
-
-        cols = Math.floor(canvas.width / fontSize);
-        if (drops.length < cols)
-          drops = drops.concat(Array(cols - drops.length).fill(1));
-
-        for (let i = 0; i < cols; i++) {
-          const char = chars[Math.floor(Math.random() * chars.length)];
-          ctx.fillText(char, i * fontSize, drops[i] * fontSize);
-          if (drops[i] * fontSize > canvas.height && Math.random() > 0.975)
-            drops[i] = 0;
-          drops[i]++;
-        }
-      }
-
-      setInterval(drawMatrix, 40);
-    </script>
+    <script src="/js/404.js"></script>
+    <script src="/js/matrix.js"></script>
   </body>
 </html>
diff --git a/frontend/js/404.js b/frontend/js/404.js
new file mode 100644
index 00000000..aef8496d
--- /dev/null
+++ b/frontend/js/404.js
@@ -0,0 +1,10 @@
+document.addEventListener("DOMContentLoaded", () => {
+  // Inject actual bad path
+  const p = window.location.pathname;
+
+  const cdLine = document.getElementById("cd-line");
+  const pathDisplay = document.getElementById("path-display");
+
+  if (cdLine) cdLine.textContent = " cd " + p;
+  if (pathDisplay) pathDisplay.textContent = p;
+});
diff --git a/frontend/js/leaderboard/compare.js b/frontend/js/leaderboard/compare.js
index 902689e9..a77c39e7 100644
--- a/frontend/js/leaderboard/compare.js
+++ b/frontend/js/leaderboard/compare.js
@@ -37,6 +37,24 @@ document.addEventListener("DOMContentLoaded", () => {
   const toggleBtn = document.getElementById("compare-mode-toggle");
   if (toggleBtn) {
     toggleBtn.addEventListener("click", toggleCompareMode);
+    toggleBtn.addEventListener("mouseover", function () {
+      this.style.background = "var(--amber-muted)";
+      this.style.borderColor = "var(--amber-dim)";
+      this.style.textShadow = "0 0 5px rgba(255, 176, 0, 0.4)";
+    });
+    toggleBtn.addEventListener("mouseout", function () {
+      if (!window.compareModeActive) {
+        this.style.background = "var(--bg-raised)";
+        this.style.borderColor = "var(--border)";
+        this.style.color = "var(--amber)";
+        this.style.textShadow = "none";
+      } else {
+        this.style.background = "var(--green-muted)";
+        this.style.borderColor = "var(--green-dim)";
+        this.style.color = "var(--green)";
+        this.style.textShadow = "0 0 5px rgba(0, 255, 65, 0.3)";
+      }
+    });
   }
 
   const closeBtn = document.getElementById("close-compare-modal");
diff --git a/frontend/leaderboard.html b/frontend/leaderboard.html
index 76af64cd..ee798e61 100644
--- a/frontend/leaderboard.html
+++ b/frontend/leaderboard.html
@@ -175,24 +175,6 @@ <h1 class="page-title">Leaderboard</h1>
               margin-right: 0.5rem;
               white-space: nowrap;
             "
-            onmouseover="
-              this.style.background = 'var(--amber-muted)';
-              this.style.borderColor = 'var(--amber-dim)';
-              this.style.textShadow = '0 0 5px rgba(255, 176, 0, 0.4)';
-            "
-            onmouseout="
-              if (!window.compareModeActive) {
-                this.style.background = 'var(--bg-raised)';
-                this.style.borderColor = 'var(--border)';
-                this.style.color = 'var(--amber)';
-                this.style.textShadow = 'none';
-              } else {
-                this.style.background = 'var(--green-muted)';
-                this.style.borderColor = 'var(--green-dim)';
-                this.style.color = 'var(--green)';
-                this.style.textShadow = '0 0 5px rgba(0, 255, 65, 0.3)';
-              }
-            "
           >
             [--compare-peers]
           </button>
@@ -751,6 +733,7 @@ <h1 class="page-title">Leaderboard</h1>
               style="
                 display: flex;
                 gap: 10px;
+                flex-wrap: wrap;
                 margin: 1.5rem 0 1rem 0;
                 justify-content: center;
               "
diff --git a/frontend/styles/main.css b/frontend/styles/main.css
index b377f3bb..e594cdf7 100644
--- a/frontend/styles/main.css
+++ b/frontend/styles/main.css
@@ -3369,3 +3369,113 @@ input[type="checkbox"].compare-checkbox:checked::after {
     display: none;
   }
 }
+
+/* Hero responsive */
+@media (max-width: 768px) {
+  .hero-title {
+    font-size: 2.8rem;
+  }
+  .hero-content {
+    padding: 2rem;
+  }
+}
+
+@media (max-width: 480px) {
+  .hero-title {
+    font-size: 2rem;
+    word-break: break-word;
+  }
+  .hero-subtitle {
+    font-size: 0.85rem;
+  }
+  .hero-content {
+    padding: 1.2rem;
+  }
+  .hero-buttons {
+    flex-direction: column;
+    width: 100%;
+  }
+  .hero-buttons .btn {
+    width: 100%;
+    max-width: 100%;
+  }
+}
+
+/* Compare Module Responsive */
+@media (max-width: 768px) {
+  .floating-compare-bar {
+    width: calc(100% - 32px);
+    max-width: 100%;
+    gap: 1rem;
+    padding: 0.75rem 1rem;
+  }
+  .floating-compare-bar .selected-list {
+    font-size: 0.78rem;
+  }
+  .compare-card {
+    padding: 20px 16px;
+  }
+  .compare-table th,
+  .compare-table td {
+    padding: 0.5rem 0.4rem;
+    font-size: 0.72rem;
+  }
+  .compare-chart-card {
+    height: 280px;
+    min-height: 280px;
+    max-height: 280px;
+  }
+  .compare-chart-card canvas {
+    height: calc(100% - 50px) !important;
+  }
+}
+
+@media (max-width: 480px) {
+  .floating-compare-bar {
+    flex-direction: column;
+    gap: 0.75rem;
+    padding: 0.8rem 1rem;
+    text-align: center;
+    bottom: 12px;
+  }
+  .floating-compare-bar .actions {
+    width: 100%;
+    justify-content: center;
+    flex-wrap: wrap;
+  }
+  .floating-compare-bar .btn-compare,
+  .floating-compare-bar .btn-clear {
+    flex: 1;
+    text-align: center;
+  }
+  .compare-card {
+    padding: 16px 12px;
+    width: 100vw;
+    max-width: 100vw;
+    border-radius: 0;
+  }
+  .compare-card-header {
+    flex-direction: column;
+    gap: 12px;
+    align-items: center;
+    text-align: center;
+  }
+  .compare-card-title {
+    font-size: 0.82rem;
+  }
+  .compare-table th,
+  .compare-table td {
+    padding: 0.4rem 0.3rem;
+    font-size: 0.65rem;
+    white-space: nowrap;
+  }
+  .compare-chart-card {
+    height: 240px;
+    min-height: 240px;
+    max-height: 240px;
+  }
+  .compare-chart-title {
+    font-size: 0.68rem;
+    margin-bottom: 0.5rem;
+  }
+}
diff --git a/server.js b/server.js
index 8ab527e7..e13fd0fc 100644
--- a/server.js
+++ b/server.js
@@ -35,6 +35,7 @@ app.use(
           "https://raw.githubusercontent.com",
           "https://leetcode-api-dun.vercel.app",
           "https://lc-backend-lyq2.onrender.com",
+          "https://cdn.jsdelivr.net",
         ],
         // Inline scripts need a per-request nonce; external scripts from 'self'
         // are allowed automatically.
@@ -165,7 +166,8 @@ app.get("/api/user/:username", async (req, res) => {
 
 // 404 handler
 app.use((req, res) => {
-  res.status(404).sendFile(path.join(__dirname, "frontend", "404.html"));
+  res.status(404);
+  serveHtml(res, path.join(__dirname, "frontend", "404.html"));
 });
 
 app.listen(PORT, () => {
