/* ============================================
   海姆立克急救法 · 互动科普站
   通用样式表
   ============================================ */

/* ---------- CSS 自定义属性（主题色） ---------- */
:root {
  --color-primary: #00bcd4;
  --color-primary-light: #4dd0e1;
  --color-primary-dark: #0097a7;
  --color-accent: #ff7043;
  --color-accent-light: #ffab91;
  --color-bg: #0f1923;
  --color-bg-card: #1a2a3a;
  --color-bg-card-hover: #1f3347;
  --color-text: #e0e0e0;
  --color-text-heading: #ffffff;
  --color-text-muted: #90a4ae;
  --color-border: #263238;
  --color-success: #66bb6a;
  --color-warning: #ffa726;
  --color-danger: #ef5350;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --shadow-card: 0 4px 20px rgba(0, 0, 0, 0.3);
  --shadow-card-hover: 0 8px 32px rgba(0, 188, 212, 0.15);
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ---------- 全局重置 ---------- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC",
               "Microsoft YaHei", "Noto Sans SC", sans-serif;
  background: linear-gradient(135deg, #0f1923 0%, #132a3a 50%, #0d1b2a 100%);
  color: var(--color-text);
  min-height: 100vh;
  line-height: 1.6;
  padding: 0;
  -webkit-font-smoothing: antialiased;
}

/* ---------- 渐变标题 ---------- */
.gradient-title {
  font-size: clamp(1.8rem, 5vw, 3rem);
  font-weight: 800;
  background: linear-gradient(135deg, var(--color-primary-light), var(--color-accent-light));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 0.5rem;
}

.gradient-subtitle {
  font-size: clamp(0.95rem, 2vw, 1.15rem);
  color: var(--color-text-muted);
  margin-bottom: 2rem;
}

/* ---------- 容器 ---------- */
.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- 导航栏 ---------- */
.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  padding: 16px 24px;
  background: rgba(15, 25, 35, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.navbar .logo {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-primary-light);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 8px;
}

.navbar .nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.navbar .nav-links a {
  color: var(--color-text-muted);
  text-decoration: none;
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  transition: var(--transition);
}

.navbar .nav-links a:hover,
.navbar .nav-links a.active {
  color: var(--color-primary-light);
  background: rgba(0, 188, 212, 0.1);
}

/* ---------- 卡片网格 ---------- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
  margin: 24px 0;
}

.card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px;
  text-decoration: none;
  color: var(--color-text);
  transition: var(--transition);
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.card:hover {
  background: var(--color-bg-card-hover);
  border-color: var(--color-primary-dark);
  transform: translateY(-4px);
  box-shadow: var(--shadow-card-hover);
}

.card:active {
  transform: translateY(-1px);
}

.card .card-icon {
  font-size: 2.4rem;
  line-height: 1;
}

.card h3 {
  font-size: 1.15rem;
  color: var(--color-text-heading);
}

.card p {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.5;
}

/* ---------- 步骤卡片 ---------- */
.step-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin-bottom: 16px;
  display: flex;
  gap: 16px;
  align-items: flex-start;
  transition: var(--transition);
}

.step-card:hover {
  border-color: var(--color-primary-dark);
  background: var(--color-bg-card-hover);
}

.step-number {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1rem;
}

.step-content {
  flex: 1;
}

.step-content h4 {
  color: var(--color-text-heading);
  margin-bottom: 4px;
  font-size: 1rem;
}

.step-content p {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* ---------- 警告框 ---------- */
.warning-box {
  background: rgba(255, 112, 67, 0.1);
  border-left: 4px solid var(--color-accent);
  border-radius: var(--radius-sm);
  padding: 16px 20px;
  margin: 20px 0;
}

.warning-box strong {
  color: var(--color-accent-light);
}

.warning-box p {
  color: var(--color-text);
  font-size: 0.92rem;
  margin-top: 4px;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 24px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  color: #fff;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(0, 188, 212, 0.3);
}

.btn-secondary {
  background: transparent;
  color: var(--color-primary-light);
  border: 1px solid var(--color-primary-dark);
}

.btn-secondary:hover {
  background: rgba(0, 188, 212, 0.1);
}

/* ---------- 页面头部 ---------- */
.page-header {
  text-align: center;
  padding: 40px 20px 20px;
}

.page-header .age-badge {
  display: inline-block;
  padding: 4px 16px;
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 600;
  background: rgba(0, 188, 212, 0.15);
  color: var(--color-primary-light);
  margin-bottom: 12px;
}

/* ---------- 响应式 ---------- */
@media (max-width: 600px) {
  .navbar {
    flex-direction: column;
    align-items: stretch;
    padding: 12px 16px;
  }

  .navbar .nav-links {
    justify-content: center;
  }

  .card-grid {
    grid-template-columns: 1fr;
  }

  .step-card {
    flex-direction: column;
    gap: 10px;
  }

  .page-header {
    padding: 24px 16px 16px;
  }
}

/* ---------- 页脚 ---------- */
.footer {
  text-align: center;
  padding: 32px 20px;
  color: var(--color-text-muted);
  font-size: 0.82rem;
  border-top: 1px solid var(--color-border);
  margin-top: 48px;
}

.footer a {
  color: var(--color-primary-light);
  text-decoration: none;
}

/* ---------- 视频演示区域 ---------- */
.video-section {
  margin: 32px 0;
}

.video-section h2 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-text-heading);
  margin-bottom: 16px;
}

.video-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.video-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 16px;
  transition: var(--transition);
}

.video-card:hover {
  border-color: var(--color-primary-dark);
}

.video-card.correct {
  border-left: 4px solid var(--color-success);
}

.video-card.wrong {
  border-left: 4px solid var(--color-danger);
}

.video-card .video-label {
  font-size: 0.85rem;
  font-weight: 700;
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.video-card.correct .video-label {
  color: var(--color-success);
}

.video-card.wrong .video-label {
  color: var(--color-danger);
}

.video-placeholder {
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #0a121c;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 8px;
  color: var(--color-text-muted);
  font-size: 0.85rem;
  border: 1px dashed var(--color-border);
}

.video-placeholder .play-icon {
  font-size: 2.4rem;
  opacity: 0.6;
}

.video-placeholder .video-desc {
  text-align: center;
  padding: 0 12px;
  line-height: 1.4;
}

@media (max-width: 600px) {
  .video-grid {
    grid-template-columns: 1fr;
  }
}

/* ---------- 工具类 ---------- */
.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.mb-3 { margin-bottom: 24px; }
.text-center { text-align: center; }