/* ============================================
   LouxiaOS 官网 - LouxiaOS 设计系统风格
   源自 LouxiaOS 桌面应用 (Tauri + React + Tailwind)
   主色：#8b5cf6 (紫色) | 背景渐变：紫→青→绿
   ============================================ */

/* ===== CSS 变量 ===== */
:root {
  --primary-50: #f5f3ff;
  --primary-100: #ede9fe;
  --primary-200: #ddd6fe;
  --primary-300: #c4b5fd;
  --primary-400: #a78bfa;
  --primary-500: #8b5cf6;
  --primary-600: #7c3aed;
  --primary-700: #6d28d9;
  --cyan-400: #22d3ee;
  --cyan-500: #06b6d4;

  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;

  --success: #10b981;
  --info: #3b82f6;
  --warning: #f59e0b;
  --danger: #ef4444;

  --font-sans: 'Inter', 'Microsoft YaHei', -apple-system, BlinkMacSystemFont, sans-serif;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 10px 10px -5px rgba(0,0,0,0.04);
  --transition: 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  --container: 1200px;
  --nav-height: 72px;
}

/* ===== 基础重置 ===== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  background: linear-gradient(135deg, #f5f3ff 0%, #ecfeff 50%, #f0fdfa 100%);
  color: var(--gray-800);
  min-height: 100vh;
  font-size: 14px;
  line-height: 1.6;
}

a {
  text-decoration: none;
  color: inherit;
}

img {
  max-width: 100%;
  display: block;
}

/* ===== 滚动条（LouisaOS 风格） ===== */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--gray-300); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--gray-400); }

/* ===== 动画 ===== */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}
@keyframes pulse-soft {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.7; }
}
.animate-fade-in { animation: fadeIn 0.5s ease-out; }
.animate-float { animation: float 3s ease-in-out infinite; }

/* ===== 导航栏 ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(229, 231, 235, 0.5);
  z-index: 100;
  transition: var(--transition);
}

.navbar.scrolled {
  box-shadow: var(--shadow-sm);
}

.nav-inner {
  max-width: var(--container);
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
}

/* Logo */
.nav-logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--primary-500), var(--primary-400));
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 18px;
  font-weight: 700;
  box-shadow: 0 2px 8px rgba(139, 92, 246, 0.3);
}

.logo-text {
  font-size: 20px;
  font-weight: 700;
  color: var(--gray-800);
}

.logo-highlight {
  color: var(--primary-500);
}

/* 导航菜单 */
.nav-menu {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-link {
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  color: var(--gray-600);
  transition: all 0.2s ease;
  position: relative;
}

.nav-link:hover {
  color: var(--primary-600);
  background: var(--primary-50);
}

.nav-link.nav-btn {
  background: linear-gradient(135deg, var(--primary-500), var(--primary-400));
  color: white;
  padding: 10px 20px;
  border-radius: var(--radius-sm);
  box-shadow: 0 2px 8px rgba(139, 92, 246, 0.3);
  margin-left: 8px;
}

.nav-link.nav-btn:hover {
  box-shadow: 0 4px 12px rgba(139, 92, 246, 0.4);
  transform: translateY(-1px);
}

/* 主题切换按钮 */
.theme-toggle {
  display: none; /* LouxiaOS 无深色模式 */
}

/* 移动端汉堡菜单 */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--gray-700);
  border-radius: 2px;
  transition: var(--transition);
}

/* ===== Hero 区域 ===== */
.hero {
  padding: 120px 24px 80px;
  position: relative;
  overflow: hidden;
  min-height: 80vh;
  display: flex;
  align-items: center;
}

.hero-inner {
  max-width: var(--container);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
}

.hero-content {
  animation: fadeIn 0.6s ease-out;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--primary-50);
  color: var(--primary-600);
  font-size: 12px;
  font-weight: 600;
  padding: 6px 14px;
  border-radius: 20px;
  margin-bottom: 20px;
  border: 1px solid var(--primary-200);
}

.hero-title {
  font-size: 44px;
  font-weight: 800;
  line-height: 1.2;
  color: var(--gray-800);
  margin-bottom: 20px;
  letter-spacing: -1px;
}

.hero-title .highlight {
  background: linear-gradient(135deg, var(--primary-500), var(--primary-400));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 16px;
  color: var(--gray-500);
  line-height: 1.7;
  margin-bottom: 32px;
  max-width: 480px;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all 0.25s ease;
  font-family: var(--font-sans);
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary-500), var(--primary-400));
  color: white;
  box-shadow: 0 2px 8px rgba(139, 92, 246, 0.3);
}

.btn-primary:hover {
  box-shadow: 0 6px 20px rgba(139, 92, 246, 0.4);
  transform: translateY(-2px);
}

.btn-outline {
  background: white;
  color: var(--gray-700);
  border: 1px solid var(--gray-200);
}

.btn-outline:hover {
  border-color: var(--primary-300);
  color: var(--primary-600);
  background: var(--primary-50);
  transform: translateY(-2px);
}

.btn-sm {
  padding: 8px 16px;
  font-size: 13px;
}

.btn-lg {
  padding: 14px 28px;
  font-size: 15px;
}

/* Hero 右图 */
.hero-visual {
  display: flex;
  align-items: center;
  justify-content: center;
  animation: fadeIn 0.8s ease-out;
}

.hero-mockup {
  width: 100%;
  max-width: 520px;
  background: white;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  overflow: hidden;
  border: 1px solid var(--gray-100);
}

.hero-mockup-header {
  background: linear-gradient(135deg, var(--primary-500), var(--primary-400));
  color: white;
  padding: 20px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.hero-mockup-header h3 {
  font-size: 15px;
  font-weight: 600;
}

.hero-mockup-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  padding: 20px;
}

.mockup-stat {
  background: var(--gray-50);
  border-radius: var(--radius-sm);
  padding: 12px;
  text-align: center;
}

.mockup-stat-value {
  font-size: 18px;
  font-weight: 700;
  color: var(--gray-800);
}

.mockup-stat-label {
  font-size: 11px;
  color: var(--gray-400);
  margin-top: 4px;
}

.hero-mockup-chart {
  padding: 0 20px 20px;
}

.chart-bar {
  display: flex;
  align-items: flex-end;
  gap: 8px;
  height: 60px;
}

.chart-bar-item {
  flex: 1;
  border-radius: 4px 4px 0 0;
  min-height: 8px;
  transition: height 0.5s ease;
}

/* Hero 装饰 */
.hero-deco {
  position: absolute;
  border-radius: 50%;
  pointer-events: none;
  opacity: 0.5;
}

.hero-deco-1 {
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(139,92,246,0.08), transparent);
  top: -100px;
  right: -100px;
}

.hero-deco-2 {
  width: 300px;
  height: 300px;
  background: radial-gradient(circle, rgba(34,211,238,0.06), transparent);
  bottom: -50px;
  left: -50px;
}

/* ===== 通用 Section ===== */
.section {
  padding: 80px 24px;
  position: relative;
}

.section-inner {
  max-width: var(--container);
  margin: 0 auto;
}

.section-header {
  text-align: center;
  margin-bottom: 48px;
}

.section-label {
  display: inline-block;
  background: var(--primary-50);
  color: var(--primary-600);
  font-size: 12px;
  font-weight: 600;
  padding: 6px 14px;
  border-radius: 20px;
  margin-bottom: 12px;
  border: 1px solid var(--primary-200);
}

.section-title {
  font-size: 32px;
  font-weight: 800;
  color: var(--gray-800);
  margin-bottom: 12px;
  letter-spacing: -0.5px;
}

.section-desc {
  font-size: 15px;
  color: var(--gray-500);
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.7;
}

/* ===== 功能特色 ===== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.feature-card {
  background: white;
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-sm);
  transition: all 0.3s ease;
  border: 1px solid var(--gray-100);
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 20px 40px rgba(139, 92, 246, 0.15);
}

.feature-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  margin-bottom: 16px;
}

.feature-icon.purple { background: var(--primary-50); color: var(--primary-500); }
.feature-icon.green { background: #ecfdf5; color: #10b981; }
.feature-icon.blue { background: #eff6ff; color: var(--info); }
.feature-icon.orange { background: #fff7ed; color: var(--warning); }

.feature-card h3 {
  font-size: 15px;
  font-weight: 600;
  color: var(--gray-800);
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 13px;
  color: var(--gray-500);
  line-height: 1.6;
}

/* ===== 使用教程 ===== */
.tutorials-section {
  background: white;
}

.tutorials-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.tutorial-card {
  background: var(--gray-50);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: all 0.3s ease;
  border: 1px solid var(--gray-100);
}

.tutorial-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 20px 40px rgba(139, 92, 246, 0.15);
}

.tutorial-card .tutorial-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  margin-bottom: 12px;
}

.tutorial-card h3 {
  font-size: 15px;
  font-weight: 600;
  color: var(--gray-800);
  margin-bottom: 8px;
}

.tutorial-card p {
  font-size: 13px;
  color: var(--gray-500);
  line-height: 1.6;
  margin-bottom: 16px;
}

.tutorial-card .tutorial-link {
  font-size: 13px;
  color: var(--primary-500);
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.tutorial-card .tutorial-link:hover {
  color: var(--primary-600);
}

/* ===== 下载更新 ===== */
.download-section {
  text-align: center;
}

.download-card {
  background: white;
  border-radius: var(--radius-lg);
  padding: 48px;
  box-shadow: var(--shadow-md);
  max-width: 600px;
  margin: 0 auto;
  border: 1px solid var(--gray-100);
}

.download-version {
  font-size: 14px;
  color: var(--gray-500);
  margin-bottom: 8px;
}

.download-version strong {
  color: var(--primary-500);
}

.download-btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 16px 32px;
  background: linear-gradient(135deg, var(--primary-500), var(--primary-400));
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.25s ease;
  font-family: var(--font-sans);
  box-shadow: 0 4px 14px rgba(139, 92, 246, 0.3);
  margin-top: 16px;
}

.download-btn:hover {
  box-shadow: 0 6px 20px rgba(139, 92, 246, 0.4);
  transform: translateY(-2px);
}

.download-meta {
  margin-top: 20px;
  font-size: 12px;
  color: var(--gray-400);
}

.download-meta a {
  color: var(--primary-500);
}

.download-meta a:hover {
  color: var(--primary-600);
}

/* ===== 关于/功能列表 ===== */
.benefits-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  max-width: 700px;
  margin: 0 auto;
}

.benefit-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 16px;
  background: white;
  border-radius: var(--radius-sm);
  border: 1px solid var(--gray-100);
}

.benefit-item .check {
  width: 24px;
  height: 24px;
  background: var(--primary-50);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary-500);
  font-size: 13px;
  flex-shrink: 0;
}

.benefit-item h4 {
  font-size: 14px;
  font-weight: 600;
  color: var(--gray-800);
  margin-bottom: 4px;
}

.benefit-item p {
  font-size: 13px;
  color: var(--gray-500);
}

/* ===== CTA 区域 ===== */
.cta-section {
  background: linear-gradient(135deg, var(--primary-500), var(--primary-600));
  padding: 64px 24px;
  text-align: center;
  color: white;
}

.cta-section h2 {
  font-size: 28px;
  font-weight: 800;
  margin-bottom: 12px;
}

.cta-section p {
  font-size: 15px;
  opacity: 0.85;
  margin-bottom: 24px;
}

.cta-section .btn {
  background: white;
  color: var(--primary-600);
  box-shadow: 0 4px 14px rgba(0,0,0,0.15);
}

.cta-section .btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.2);
}

/* ===== 页脚 ===== */
.footer {
  background: white;
  border-top: 1px solid var(--gray-100);
  padding: 40px 24px 24px;
}

.footer-inner {
  max-width: var(--container);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
}

.footer-brand p {
  font-size: 13px;
  color: var(--gray-500);
  margin-top: 12px;
  line-height: 1.6;
}

.footer-col h4 {
  font-size: 13px;
  font-weight: 600;
  color: var(--gray-800);
  margin-bottom: 16px;
}

.footer-col a {
  display: block;
  font-size: 13px;
  color: var(--gray-500);
  padding: 6px 0;
  transition: color 0.2s ease;
}

.footer-col a:hover {
  color: var(--primary-500);
}

.footer-bottom {
  max-width: var(--container);
  margin: 24px auto 0;
  padding-top: 20px;
  border-top: 1px solid var(--gray-100);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 12px;
  color: var(--gray-400);
}

/* ===== 页面通用 ===== */
.page-hero {
  padding: 120px 24px 60px;
  text-align: center;
  position: relative;
}

.page-hero h1 {
  font-size: 36px;
  font-weight: 800;
  color: var(--gray-800);
  margin-bottom: 12px;
}

.page-hero p {
  font-size: 15px;
  color: var(--gray-500);
  max-width: 500px;
  margin: 0 auto;
}

.page-content {
  padding: 0 24px 80px;
}

/* ===================================================================
   兼容层 — 旧页面类名映射（tutorials / download / about / login）
   保持双端兼容，旧页面无需改 HTML
   =================================================================== */

/* ---- 容器布局 ---- */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.content-section {
  padding: 0 24px 80px;
}

.page-header {
  padding: 120px 24px 60px;
  text-align: center;
}
.page-header h1 {
  font-size: 36px;
  font-weight: 800;
  color: var(--gray-800);
  margin-bottom: 12px;
}
.page-header p {
  font-size: 15px;
  color: var(--gray-500);
  max-width: 500px;
  margin: 0 auto;
}

/* ---- 导航兼容 ---- */
.navbar-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 20px;
  font-weight: 700;
  color: var(--gray-800);
}
.navbar-links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}
.navbar-links a {
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  color: var(--gray-600);
  transition: all 0.2s ease;
}
.navbar-links a:hover {
  color: var(--primary-600);
  background: var(--primary-50);
}
.navbar-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--gray-700);
  border-radius: 2px;
  transition: var(--transition);
}

/* ---- 页面通用 ---- */
.page-content {
  padding: 0 24px 80px;
}

/* ---- 教程列表页 ---- */
.tutorial-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.tutorial-item {
  display: block;
  background: white;
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: all 0.3s ease;
  border: 1px solid var(--gray-100);
}
.tutorial-item:hover {
  transform: translateY(-4px);
  box-shadow: 0 20px 40px rgba(139, 92, 246, 0.15);
}
.tutorial-item .tag {
  display: inline-block;
  background: var(--primary-50);
  color: var(--primary-600);
  font-size: 12px;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 20px;
  margin-bottom: 12px;
}
.tutorial-item h3 {
  font-size: 15px;
  font-weight: 600;
  color: var(--gray-800);
  margin-bottom: 8px;
}
.tutorial-item p {
  font-size: 13px;
  color: var(--gray-500);
  line-height: 1.6;
  margin-bottom: 12px;
}
.tutorial-item .meta {
  font-size: 12px;
  color: var(--gray-400);
}

/* ---- 教程详情页 ---- */
.tutorial-detail {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 24px;
}
.back-link {
  display: inline-block;
  margin-bottom: 24px;
  font-size: 14px;
  color: var(--primary-500);
}
.back-link:hover {
  color: var(--primary-600);
}
.tutorial-detail h1 {
  font-size: 28px;
  font-weight: 800;
  color: var(--gray-800);
  margin-bottom: 16px;
}
.tutorial-detail .meta {
  font-size: 13px;
  color: var(--gray-400);
  margin-bottom: 24px;
}
.tutorial-detail .content {
  font-size: 14px;
  color: var(--gray-700);
  line-height: 1.8;
}
.tutorial-detail .content img {
  max-width: 100%;
  border-radius: var(--radius-sm);
  margin: 20px 0;
}

/* ---- 下载页面 ---- */
.download-page {
  text-align: center;
}
.version-row {
  display: flex;
  align-items: center;
  gap: 24px;
  padding: 20px;
  background: white;
  border-radius: var(--radius-md);
  border: 1px solid var(--gray-100);
  margin-bottom: 12px;
  transition: all 0.3s ease;
  animation: fadeIn 0.5s ease-out;
}
.version-row:hover {
  box-shadow: var(--shadow-sm);
}
.version-row .ver {
  font-size: 16px;
  font-weight: 700;
  color: var(--gray-800);
}
.version-row .date {
  font-size: 12px;
  color: var(--gray-400);
  margin-top: 4px;
}
.version-row .notes {
  flex: 1;
  font-size: 13px;
  color: var(--gray-500);
  text-align: left;
}

/* ---- 关于页面 ---- */
.about-content {
  max-width: 700px;
  margin: 0 auto;
}
.about-content h2 {
  font-size: 22px;
  font-weight: 700;
  color: var(--gray-800);
  margin: 40px 0 16px;
}
.about-content p {
  font-size: 14px;
  color: var(--gray-600);
  line-height: 1.8;
  margin-bottom: 16px;
}

/* ---- 登录页面 ---- */
.login-page {
  padding-top: var(--nav-height);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: calc(var(--nav-height) + 40px) 24px 60px;
}
.login-box {
  width: 100%;
  max-width: 420px;
  background: white;
  border-radius: var(--radius-lg);
  padding: 40px;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--gray-100);
}
.login-box h1 {
  font-size: 22px;
  font-weight: 700;
  color: var(--gray-800);
  text-align: center;
  margin-bottom: 8px;
}
.login-box > p {
  font-size: 13px;
  color: var(--gray-500);
  text-align: center;
  margin-bottom: 24px;
}
.tabs {
  display: flex;
  gap: 0;
  margin-bottom: 24px;
  border-radius: var(--radius-sm);
  overflow: hidden;
  border: 1px solid var(--gray-200);
}
.tabs button {
  flex: 1;
  padding: 12px;
  border: none;
  background: var(--gray-50);
  color: var(--gray-500);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  font-family: var(--font-sans);
}
.tabs button.active {
  background: linear-gradient(135deg, var(--primary-500), var(--primary-400));
  color: white;
}
.form-group {
  margin-bottom: 20px;
}
.form-group label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--gray-700);
  margin-bottom: 6px;
}
.form-group input {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-family: var(--font-sans);
  background: var(--gray-50);
  color: var(--gray-800);
  transition: all 0.2s ease;
  outline: none;
  box-sizing: border-box;
}
.form-group input:focus {
  border-color: var(--primary-400);
  box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.1);
  background: white;
}
.form-error {
  background: #fef2f2;
  color: #dc2626;
  font-size: 13px;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  margin-bottom: 16px;
  border: 1px solid #fecaca;
}
.form-success {
  background: #ecfdf5;
  color: #059669;
  font-size: 13px;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  margin-bottom: 16px;
  border: 1px solid #a7f3d0;
}
.btn-block {
  width: 100%;
  justify-content: center;
}

/* ---- 加载动画 ---- */
.loading {
  text-align: center;
  padding: 40px;
  color: var(--gray-400);
  font-size: 14px;
}
.spinner {
  width: 32px;
  height: 32px;
  border: 3px solid var(--gray-200);
  border-top-color: var(--primary-500);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: 0 auto 12px;
}
@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ---- 响应式覆盖 ---- */
@media (max-width: 1024px) {
  .tutorial-list { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  .navbar-links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: white;
    flex-direction: column;
    padding: 16px;
    border-bottom: 1px solid var(--gray-100);
    box-shadow: var(--shadow-md);
    display: none;
  }
  .navbar-links.open { display: flex; }
  .hamburger { display: flex; }
  .tutorial-list { grid-template-columns: 1fr; }
  .version-row { flex-direction: column; text-align: center; }
  .version-row .notes { text-align: center; }
  .login-box { padding: 24px; }
  .page-header { padding: 100px 16px 40px; }
  .page-header h1 { font-size: 28px; }
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
  .hero-inner { grid-template-columns: 1fr; text-align: center; }
  .hero-subtitle { margin: 0 auto 32px; }
  .hero-actions { justify-content: center; }
  .hero-mockup { max-width: 420px; margin: 0 auto; }
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .tutorials-grid { grid-template-columns: repeat(2, 1fr); }
  .hero-title { font-size: 34px; }
  .footer-inner { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  .nav-menu {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: white;
    flex-direction: column;
    padding: 16px;
    border-bottom: 1px solid var(--gray-100);
    box-shadow: var(--shadow-md);
    display: none;
  }
  .nav-menu.open { display: flex; }
  .nav-toggle { display: flex; }
  .nav-link.nav-btn { margin-left: 0; text-align: center; }
  .hero { padding: 100px 16px 60px; }
  .hero-title { font-size: 28px; }
  .hero-mockup { display: none; }
  .features-grid { grid-template-columns: 1fr; }
  .tutorials-grid { grid-template-columns: 1fr; }
  .benefits-list { grid-template-columns: 1fr; }
  .section { padding: 48px 16px; }
  .section-title { font-size: 24px; }
  .footer-inner { grid-template-columns: 1fr; }
  .footer-bottom { flex-direction: column; gap: 8px; text-align: center; }
  .download-card { padding: 24px; }
}