/* ========== 全局重置与变量 ========== */
:root {
  --primary: #1a6dd4;
  --primary-hover: #1255a8;
  --text: #1e1e2e;
  --text-secondary: #585861;
  --bg: #ffffff;
  --bg-soft: #f8f9fb;
  --border: #eaeaef;
  --radius: 10px;
  --shadow: 0 4px 12px rgba(0,0,0,0.05);
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.wrapper {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ========== 导航栏 ========== */
header {
  position: sticky;
  top: 0;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  z-index: 100;
}

.nav-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 72px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.35rem;
  color: var(--text);
}

.logo img {
  width: 32px;
  height: 32px;
}

nav {
  display: flex;
  gap: 28px;
  height: 100%;
  align-items: center;
}

nav a {
  text-decoration: none;
  color: var(--text-secondary);
  font-weight: 500;
  font-size: 0.95rem;
  transition: color 0.2s;
  position: relative;
}

nav a:hover,
nav a.active {
  color: var(--primary);
}

nav a.active::after {
  content: "";
  position: absolute;
  bottom: -22px;
  left: 0;
  width: 100%;
  height: 3px;
  background: var(--primary);
  border-radius: 2px;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.6rem;
  cursor: pointer;
  color: var(--text);
  padding: 8px;
}

/* ========== Hero 区域 ========== */
.hero {
  padding: 60px 0 40px;
  text-align: center;
}

.hero-badge {
  display: inline-block;
  background: #eef4ff;
  color: var(--primary);
  padding: 6px 18px;
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 28px;
}

.hero h1 {
  font-size: 2.8rem;
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 24px;
  color: var(--text);
}

.hero-highlight {
  background: linear-gradient(135deg, var(--primary), #4f8edc);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  max-width: 780px;
  margin: 0 auto 36px;
  color: var(--text-secondary);
  font-size: 1.05rem;
  line-height: 1.7;
  text-align: center;
}

.hero-cta {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 40px;
}

.btn-primary {
  background: var(--primary);
  color: #fff;
  padding: 14px 34px;
  border-radius: 30px;
  font-weight: 600;
  text-decoration: none;
  transition: background 0.2s, transform 0.1s;
  box-shadow: 0 6px 18px rgba(26,109,212,0.25);
}

.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-2px);
}

.btn-outline {
  background: #fff;
  color: var(--text);
  padding: 14px 34px;
  border-radius: 30px;
  font-weight: 600;
  text-decoration: none;
  border: 1px solid var(--border);
  transition: background 0.2s, border-color 0.2s;
}

.btn-outline:hover {
  background: var(--bg-soft);
  border-color: #cbcbd6;
}

/* 协议标签云 */
.protocol-cloud {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  margin-bottom: 50px;
}

.protocol-cloud span {
  background: #f0f0f5;
  color: #4a4a5a;
  padding: 5px 14px;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.3px;
}

/* 媒体展示 */
.media-strip {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  max-width: 960px;
  margin: 0 auto;
}

.screenshot-box {
  background: #f4f4f7;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
}

.screenshot-box img {
  width: 100%;
  height: auto;
  display: block;
}

.video-wrap {
  aspect-ratio: 16 / 9;
  background: #000;
  border-radius: var(--radius);
  overflow: hidden;
}

.video-wrap iframe {
  width: 100%;
  height: 100%;
  border: 0;
}

/* ========== 信任指标条 ========== */
.trust-bar {
  background: var(--bg-soft);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding: 28px 0;
}

.trust-items {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 40px;
}

.trust-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
}

.trust-num {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--primary);
}

.trust-item span:last-child {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* ========== 通用区块标题 ========== */
.sec-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 16px;
  text-align: center;
  color: var(--text);
}

.sec-sub {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 48px;
  color: var(--text-secondary);
  font-size: 1rem;
}

/* ========== 功能卡片网格 ========== */
.features,
.topics,
.quickstart {
  padding: 80px 0;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 28px;
}

.card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 24px;
  transition: box-shadow 0.25s, transform 0.2s;
}

.card:hover {
  box-shadow: var(--shadow);
  transform: translateY(-4px);
}

.card-icon {
  font-size: 2rem;
  margin-bottom: 16px;
  display: block;
}

.card h3 {
  font-size: 1.15rem;
  font-weight: 650;
  margin-bottom: 12px;
  color: var(--text);
}

.card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.65;
}

/* ========== 三步上手流程 ========== */
.steps-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
  margin-bottom: 30px;
}

.step {
  background: #f8f9fb;
  border-radius: var(--radius);
  padding: 28px 24px;
  text-align: center;
  flex: 1;
  min-width: 200px;
  max-width: 260px;
  border: 1px solid var(--border);
}

.step-num {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--primary);
  opacity: 0.7;
  margin-bottom: 8px;
}

.step h4 {
  font-size: 1.05rem;
  margin-bottom: 10px;
}

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

.step-arrow {
  font-size: 1.8rem;
  color: #b0b0c0;
  display: none;
}

.quickstart-hint {
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.quickstart-hint a {
  color: var(--primary);
  font-weight: 500;
}

/* ========== 专题引导卡 ========== */
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.topic-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  text-decoration: none;
  color: inherit;
  display: flex;
  flex-direction: column;
  transition: box-shadow 0.2s, border-color 0.2s;
}

.topic-card:hover {
  box-shadow: var(--shadow);
  border-color: #c0c0d0;
}

.topic-badge {
  display: inline-block;
  background: #eef4ff;
  color: var(--primary);
  padding: 3px 12px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 600;
  margin-bottom: 14px;
  width: fit-content;
}

.topic-card h3 {
  font-size: 1.2rem;
  margin-bottom: 8px;
}

.topic-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 16px;
  flex: 1;
}

.topic-link {
  color: var(--primary);
  font-weight: 600;
  font-size: 0.9rem;
}

/* ========== 时间线 ========== */
.timeline {
  padding: 80px 0;
  background: var(--bg-soft);
}

.tl-block {
  border-left: 3px solid var(--primary);
  padding-left: 28px;
  margin-left: 20px;
  margin-bottom: 40px;
  position: relative;
}

.tl-block:last-child {
  margin-bottom: 0;
}

.tl-year {
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 8px;
  display: block;
  font-size: 0.9rem;
  letter-spacing: 0.5px;
}

.tl-block h3 {
  font-size: 1.15rem;
  margin-bottom: 10px;
}

.tl-block p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  max-width: 700px;
}

/* ========== 页脚 ========== */
footer {
  background: #1a1a22;
  color: #ddd;
  padding: 56px 0 28px;
  font-size: 0.9rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 36px;
  margin-bottom: 40px;
  border-bottom: 1px solid #2e2e3a;
  padding-bottom: 36px;
}

.footer-col h4 {
  color: #fff;
  margin-bottom: 16px;
  font-size: 0.95rem;
  font-weight: 600;
}

.footer-col ul {
  list-style: none;
}

.footer-col li {
  margin-bottom: 10px;
}

.footer-col a {
  color: #aaa;
  text-decoration: none;
  transition: color 0.2s;
}

.footer-col a:hover {
  color: #fff;
}

.footer-about p {
  color: #aaa;
  line-height: 1.7;
  font-size: 0.85rem;
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  color: #777;
  font-size: 0.8rem;
}

/* ========== 响应式 ========== */
@media (max-width: 768px) {
  .nav-bar {
    flex-wrap: wrap;
    height: auto;
    padding: 16px 20px;
  }

  nav {
    display: none;
    width: 100%;
    flex-direction: column;
    gap: 10px;
    background: #fff;
    padding: 16px 0;
  }

  nav.nav-open {
    display: flex;
  }

  .nav-toggle {
    display: block;
  }

  nav a.active::after {
    display: none;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .media-strip {
    grid-template-columns: 1fr;
  }

  .steps-row {
    flex-direction: column;
  }

  .step-arrow {
    display: block;
  }

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

  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .trust-items {
    gap: 24px;
  }

  .hero-cta {
    flex-direction: column;
    align-items: center;
  }

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