更新前端静态网页获取方式，放弃使用后端获取api

frontend/public/60sapi/娱乐消遣/随机搞笑段子/css/background.css

@@ -0,0 +1,36 @@
+body {
+    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
+    margin: 0;
+    min-height: 100vh;
+    overflow-x: hidden;
+    transition: background 0.5s ease;
+}
+
+/* Hand-drawn Comic Theme Background - NEW VIBRANT VERSION */
+body.theme-comic {
+    background: linear-gradient(-45deg, #ff7e5f, #feb47b, #ffcc80, #ffecb3);
+    background-size: 400% 400%;
+    animation: gradientBG 15s ease infinite;
+}
+
+@keyframes gradientBG {
+    0% {
+        background-position: 0% 50%;
+    }
+    50% {
+        background-position: 100% 50%;
+    }
+    100% {
+        background-position: 0% 50%;
+    }
+}
+
+/* Placeholder for Emoji Theme Background */
+body.theme-emoji {
+    background-color: #fffde7;
+}
+
+/* Placeholder for Retro TV Theme Background */
+body.theme-retro {
+    background-color: #3d2b1f;
+}