feat: 完成navbar隐藏优化和侧边栏冻结功能

- 优化navbar滚动隐藏逻辑，更敏感响应
- 添加返回顶部按钮，固定在右下角
- 实现profile页面侧边栏真正冻结效果
- 修复首页滑动指示器位置
- 优化整体布局确保首屏内容完整显示

src/app/globals.css

@@ -1,15 +1,13 @@
+@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');
 @import "tailwindcss";
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
 
 :root {
   --background: #ffffff;
   --foreground: #171717;
-}
-
-@theme inline {
-  --color-background: var(--background);
-  --color-foreground: var(--foreground);
-  --font-sans: var(--font-geist-sans);
-  --font-mono: var(--font-geist-mono);
+  --navbar-height: 64px; /* 与pt-16对应 */
 }
 
 @media (prefers-color-scheme: dark) {
@@ -20,7 +18,90 @@
 }
 
 body {
-  background: var(--background);
   color: var(--foreground);
-  font-family: Arial, Helvetica, sans-serif;
+  background: var(--background);
+  font-family: 'Inter', Arial, Helvetica, sans-serif;
+}
+
+/* Custom utility classes */
+.text-balance {
+  text-wrap: balance;
+}
+
+/* Custom component classes */
+.btn-carrot {
+  background-color: #f97316;
+  color: white;
+  font-weight: 500;
+  padding: 0.5rem 1rem;
+  border-radius: 0.5rem;
+  transition: background-color 0.2s;
+  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
+}
+
+.btn-carrot:hover {
+  background-color: #ea580c;
+  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
+}
+
+.btn-carrot-outline {
+  border: 2px solid #f97316;
+  color: #f97316;
+  font-weight: 500;
+  padding: 0.5rem 1rem;
+  border-radius: 0.5rem;
+  transition: all 0.2s;
+}
+
+.btn-carrot-outline:hover {
+  background-color: #f97316;
+  color: white;
+}
+
+.card-minecraft {
+  background-color: white;
+  border: 2px solid #fed7aa;
+  border-radius: 0.5rem;
+  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
+  transition: all 0.2s;
+}
+
+.card-minecraft:hover {
+  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
+}
+
+@media (prefers-color-scheme: dark) {
+  .card-minecraft {
+    background-color: #1f2937;
+    border-color: #c2410c;
+  }
+}
+
+.text-gradient {
+  background: linear-gradient(to right, #fb923c, #f97316);
+  background-clip: text;
+  -webkit-background-clip: text;
+  color: transparent;
+}
+
+.bg-gradient-carrot {
+  background: linear-gradient(to bottom right, #fb923c, #f97316, #ea580c);
+}
+
+/* 现代布局解决方案 */
+@layer utilities {
+  /* 全屏减去navbar高度 */
+  .h-screen-nav {
+    height: calc(100vh - var(--navbar-height));
+  }
+  
+  /* 侧栏最大高度，确保底部按钮可见 */
+  .sidebar-max-height {
+    max-height: calc(100vh - var(--navbar-height) - 120px);
+  }
+  
+  /* 首页hero section专用高度 */
+  .min-h-screen-nav {
+    min-height: calc(100vh - var(--navbar-height));
+  }
 }