:root {
  /* 核心色板 - 能量绿 */
  --primary-hue: 142;
  --primary-dark: hsl(var(--primary-hue), 76%, 25%);    /* 深邃 */
  --primary-main: hsl(var(--primary-hue), 71%, 45%);    /* 品牌主色 */
  --primary-bright: hsl(var(--primary-hue), 80%, 60%);  /* 高光 */
  --primary-glow: hsl(var(--primary-hue), 90%, 70%);    /* 发光 */

  /* 中性色板 */
  --bg-base: #ffffff;
  --bg-alt: #f8fafc;
  --text-main: #0f172a;
  --text-muted: #475569;
  --border-light: #e2e8f0;
  
  /* 空间与圆角 */
  --radius-xl: 24px;
  --radius-lg: 16px;
  --radius-md: 12px;
  --container-width: 1280px;
  
  /* 阴影系统 */
  --shadow-soft: 0 4px 20px -2px rgba(22, 163, 74, 0.08);
  --shadow-glow: 0 8px 30px -5px rgba(34, 197, 94, 0.4);
  --shadow-card: 0 10px 40px -10px rgba(0,0,0,0.05);
}

/* 全局重置与字体 */
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  color: var(--text-main);
  background: var(--bg-base);
  line-height: 1.6;
  overflow-x: hidden;
}

a { text-decoration: none; color: inherit; transition: all 0.3s ease; }
ul { list-style: none; }

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

/* =========================================
   Navbar: 悬浮玻璃顶栏
   ========================================= */
.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 72px;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255,255,255,0.5);
  transition: all 0.3s ease;
}

.site-nav.scrolled {
  background: rgba(255, 255, 255, 0.95);
  box-shadow: 0 4px 20px rgba(0,0,0,0.03);
}

.site-nav .inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-weight: 800;
  font-size: 24px;
  background: linear-gradient(135deg, var(--primary-dark), var(--primary-main));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.5px;
}

.nav-links {
  display: flex;
  align-items: center;
}

.nav-links > * {
  margin-right: 32px;
}

.nav-links > *:last-child {
  margin-right: 0;
}

.nav-links a {
  font-weight: 500;
  color: var(--text-muted);
  font-size: 15px;
}

.nav-links a:hover {
  color: var(--primary-main);
}

/* 按钮系统 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 28px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 16px;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  letter-spacing: 0.5px;
}

.btn.primary {
  background: linear-gradient(135deg, var(--primary-main), var(--primary-dark));
  color: white;
  box-shadow: 0 4px 15px rgba(34, 197, 94, 0.3);
  position: relative;
  overflow: hidden;
}

.btn.primary::after {
  content: '';
  position: absolute;
  top: 0; left: -100%;
  width: 100%; height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
  transition: 0.5s;
}

.btn.primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(34, 197, 94, 0.4);
}

.btn.primary:hover::after {
  left: 100%;
}

.btn.ghost {
  background: transparent;
  color: var(--primary-dark);
  border: 2px solid rgba(34, 197, 94, 0.2);
}

.btn.ghost:hover {
  background: rgba(34, 197, 94, 0.05);
  border-color: var(--primary-main);
}

.btn-sm { padding: 8px 20px; font-size: 14px; }

/* =========================================
   Hero Section: 能量引擎
   ========================================= */
.hero {
  position: relative;
  padding: 160px 0 100px;
  background: radial-gradient(circle at 50% 0%, #f0fdf4 0%, #ffffff 60%);
  overflow: hidden;
}

/* 动态背景网格 */
.hero::before {
  content: '';
  position: absolute;
  top: 0; left: 0; width: 100%; height: 100%;
  background-image: linear-gradient(#e2e8f0 1px, transparent 1px), linear-gradient(90deg, #e2e8f0 1px, transparent 1px);
  background-size: 40px 40px;
  opacity: 0.3;
  z-index: 0;
  mask-image: linear-gradient(to bottom, rgba(0,0,0,1), rgba(0,0,0,0));
  -webkit-mask-image: linear-gradient(to bottom, rgba(0,0,0,1), rgba(0,0,0,0));
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  margin: 0 auto;
  text-align: center;
}

/* 动态标签 */
.hero-badge {
  display: inline-flex;
  align-items: center;
  padding: 6px 16px;
  background: rgba(34, 197, 94, 0.1);
  color: var(--primary-dark);
  border-radius: 999px;
  font-weight: 600;
  font-size: 14px;
  margin-bottom: 24px;
  border: 1px solid rgba(34, 197, 94, 0.2);
  animation: fadeInDown 0.8s ease-out;
}

.hero-badge .dot {
  width: 8px; height: 8px;
  background: var(--primary-main);
  border-radius: 50%;
  margin-right: 8px;
  box-shadow: 0 0 10px var(--primary-main);
  animation: pulse 2s infinite;
}

.hero h1 {
  font-size: 64px;
  line-height: 1.1;
  font-weight: 900;
  letter-spacing: -1.5px;
  margin-bottom: 24px;
  background: linear-gradient(180deg, var(--text-main), #334155);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  animation: fadeInUp 0.8s ease-out 0.1s backwards;
}

.hero h1 .highlight {
  color: var(--primary-main);
  -webkit-text-fill-color: var(--primary-main);
  position: relative;
  display: inline-block;
}

/* 下划线动画 */
.hero h1 .highlight::after {
  content: '';
  position: absolute;
  bottom: 8px;
  left: 0;
  width: 100%;
  height: 12px;
  background: rgba(74, 222, 128, 0.3);
  z-index: -1;
  transform: skewX(-15deg);
}

.hero p {
  font-size: 20px;
  color: var(--text-muted);
  margin-bottom: 40px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
  animation: fadeInUp 0.8s ease-out 0.2s backwards;
}

.hero-actions {
  display: flex;
  justify-content: center;
  animation: fadeInUp 0.8s ease-out 0.3s backwards;
}

.hero-actions > * {
  margin-right: 16px;
}

.hero-actions > *:last-child {
  margin-right: 0;
}

/* =========================================
   Live Demo: 即时反馈引擎特效
   ========================================= */
.live-demo-wrapper {
  margin-top: 64px;
  position: relative;
  perspective: 1000px;
  animation: fadeInUp 1s ease-out 0.5s backwards;
}

.live-card {
  background: white;
  border-radius: var(--radius-xl);
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.1);
  border: 1px solid rgba(255,255,255,0.8);
  overflow: hidden;
  max-width: 900px;
  margin: 0 auto;
  transform: rotateX(2deg);
  transition: transform 0.5s ease;
}

.live-card:hover {
  transform: rotateX(0deg) translateY(-5px);
  box-shadow: 0 30px 60px -12px rgba(34, 197, 94, 0.15);
}

/* 模拟界面 Header */
.card-header {
  padding: 16px 24px;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  background: #fafafa;
}

.card-header > * {
  margin-right: 12px;
}

.card-header > *:last-child {
  margin-right: 0;
}

.traffic-lights { 
  display: flex; 
}

.traffic-lights .light {
  margin-right: 6px;
}

.traffic-lights .light:last-child {
  margin-right: 0;
}
.light { width: 10px; height: 10px; border-radius: 50%; }
.light.red { background: #ef4444; }
.light.yellow { background: #f59e0b; }
.light.green { background: #22c55e; }
.address-bar {
  flex: 1;
  height: 28px;
  background: white;
  border-radius: 6px;
  border: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  padding-left: 10px;
  font-size: 12px;
  color: var(--text-muted);
}

/* 模拟界面 Body */
.card-body {
  padding: 40px;
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  column-gap: 40px;
  row-gap: 40px;
  align-items: center;
}

/* 左侧：问题区 */
.question-box h3 {
  font-size: 24px;
  margin-bottom: 24px;
}
.option {
  display: block;
  width: 100%;
  padding: 16px;
  margin-bottom: 12px;
  border: 2px solid var(--border-light);
  border-radius: var(--radius-md);
  background: white;
  text-align: left;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  position: relative;
  overflow: hidden;
}
.option:hover { border-color: var(--primary-bright); background: var(--bg-alt); }

/* 模拟选对特效 */
.option.correct {
  border-color: var(--primary-main);
  background: #f0fdf4;
  color: var(--primary-dark);
}
.option.correct::after {
  content: '✓';
  position: absolute;
  right: 16px;
  font-weight: bold;
}

/* 右侧：实时反馈仪表盘 */
.feedback-panel {
  background: #f8fafc;
  padding: 24px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-light);
}
.stat-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}
.stat-label { font-size: 14px; color: var(--text-muted); }
.stat-val { font-weight: 700; font-size: 18px; color: var(--text-main); }

/* 动态进度条 */
.progress-group { margin-top: 20px; }
.pg-label { font-size: 12px; margin-bottom: 6px; display: flex; justify-content: space-between; }
.pg-track { height: 8px; background: #e2e8f0; border-radius: 4px; overflow: hidden; }
.pg-fill {
  height: 100%;
  background: var(--primary-main);
  width: 0;
  transition: width 1s cubic-bezier(0.2, 0.8, 0.2, 1);
  position: relative;
}
/* 进度条光效 */
.pg-fill::after {
  content: '';
  position: absolute;
  top: 0; left: 0; bottom: 0; right: 0;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.6), transparent);
  transform: translateX(-100%);
  animation: shimmer 2s infinite;
}

/* =========================================
   动画定义
   ========================================= */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInDown {
  from { opacity: 0; transform: translateY(-20px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes pulse {
  0% { box-shadow: 0 0 0 0 rgba(34, 197, 94, 0.4); }
  70% { box-shadow: 0 0 0 10px rgba(34, 197, 94, 0); }
  100% { box-shadow: 0 0 0 0 rgba(34, 197, 94, 0); }
}

@keyframes shimmer {
  100% { transform: translateX(100%); }
}

/* =========================================
   Feature Cards: 特性展示
   ========================================= */
.features-section {
  padding: 100px 0;
  background: white;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  column-gap: 32px;
  row-gap: 32px;
  margin-top: 64px;
}

.feature-card {
  padding: 40px 32px;
  border-radius: var(--radius-xl);
  background: white;
  border: 1px solid var(--border-light);
  transition: all 0.3s ease;
  position: relative;
  z-index: 1;
}

.feature-card:hover {
  border-color: transparent;
  box-shadow: var(--shadow-card);
  transform: translateY(-5px);
}

.icon-box {
  width: 64px; height: 64px;
  background: #f0fdf4;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  margin-bottom: 24px;
  color: var(--primary-main);
  transition: all 0.3s ease;
}

.feature-card:hover .icon-box {
  background: var(--primary-main);
  color: white;
  transform: scale(1.1) rotate(3deg);
}

.feature-card h3 {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 12px;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 15px;
}

/* =========================================
   响应式适配
   ========================================= */
@media (max-width: 1024px) {
  .hero h1 { font-size: 48px; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .nav-links { display: none; } /* 暂时隐藏，后续可加汉堡菜单 */
  .hero { padding-top: 120px; }
  .hero h1 { font-size: 36px; }
  .card-body { grid-template-columns: 1fr; padding: 24px; }
  .feature-grid { grid-template-columns: 1fr; }
  .live-card { margin: 0 16px; }
}