:root {
  --c-text: #1D1D1F;          /* 主文字 / 深色按钮 */
  --c-text-2: #86868B;        /* 次级文字 */
  --c-accent: #0066CC;        /* 链接 / 强调蓝色 */
  --c-bg-light: #F5F5F7;      /* 浅色区块、卡片、徽章 */
  --c-border: #E5E5EA;        /* 分隔线 / 描边 */
  --c-white: #FFFFFF;
  --c-ink: #121215;           /* 页脚深色背景 */
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-display: 'Outfit', var(--font-body);
  --container: 1280px;   /* 1200 内容 + 2x40 内边距，等宽于设计稿 */
}

*,
*::before,
*::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--c-text);
  background: var(--c-white);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { display: block; max-width: 100%; }
a { text-decoration: none; color: inherit; }

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding-left: 40px;
  padding-right: 40px;
}

/* ---------- 顶部导航 ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--c-white);
  border-bottom: 1px solid var(--c-border);
}
.nav-inner {
  position: relative;
  height: 64px;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  justify-self: start;
}
.brand-logo {
  width: 124px;
  height: 19px;
  object-fit: contain;
}
.brand-sep {
  width: 1px;
  height: 14px;
  background: var(--c-border);
}
.brand-name {
  font-family: var(--font-display);
  font-weight: 500;
  font-size: 14px;
  line-height: 18px;
  color: var(--c-text-2);
}
.nav-links {
  justify-self: center;
  display: flex;
  align-items: center;
  gap: 32px;
}
.nav-link {
  font-size: 13px;
  line-height: 16px;
  color: var(--c-text-2);
  transition: color .15s ease;
}
.nav-link:hover { color: var(--c-text); }
.nav-link.is-active { font-weight: 600; color: var(--c-text); }
.nav-badge {
  justify-self: end;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: var(--c-bg-light);
  border-radius: 20px;
  padding: 4px 10px;
  font-size: 11px;
  line-height: 13px;
  color: var(--c-text-2);
  white-space: nowrap;
}
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 40px;
  height: 40px;
  padding: 8px;
  background: transparent;
  border: 0;
  cursor: pointer;
}
.nav-toggle span {
  display: block;
  height: 2px;
  width: 100%;
  background: var(--c-text);
  border-radius: 2px;
  transition: transform .2s ease, opacity .2s ease;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 41px;
  padding: 12px 24px;
  border-radius: 100px;
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 500;
  line-height: 17px;
  border: 1px solid transparent;
  cursor: pointer;
  white-space: nowrap;
  transition: transform .12s ease, box-shadow .15s ease, background .15s ease;
}
.btn svg { flex-shrink: 0; }
.btn-primary {
  background: var(--c-text);
  color: var(--c-white);
}
.btn-primary:hover {
  background: #2b2b2e;
  box-shadow: 0 6px 18px rgba(0,0,0,.16);
  transform: translateY(-1px);
}
.btn-secondary {
  background: var(--c-white);
  color: var(--c-text);
  border-color: var(--c-border);
}
.btn-secondary:hover {
  background: var(--c-bg-light);
  transform: translateY(-1px);
}

/* ---------- Hero ---------- */
.hero {
  background: var(--c-white);
  padding: 80px 0 100px;
}
.hero-copy,
.hero-actions,
.hero-visual {
  display: flex;
  flex-direction: column;
  align-items: center;
}
.hero-copy { gap: 20px; margin-bottom: 48px; }
.hero-title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2.4rem, 5.4vw, 4rem);   /* 设计值 64px */
  line-height: 1.19;
  text-align: center;
  color: var(--c-text);
  max-width: 800px;
}
.hero-subtitle {
  margin: 0;
  font-size: 20px;
  line-height: 1.6;
  text-align: center;
  color: var(--c-text-2);
  max-width: 800px;
}
.hero-actions { gap: 16px; }
.buttons-row {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 16px;
}
.hero-meta {
  font-size: 12px;
  line-height: 15px;
  color: var(--c-text-2);
  text-align: center;
}
.hero-visual { margin-top: 48px; }
.hero-visual img {
  width: 100%;
  max-width: 1000px;
  height: auto;
  border-radius: 4px;
  object-fit: contain;
}

/* ---------- 教程区块 ---------- */
.tutorials {
  background: var(--c-white);
  padding: 120px 0;
}
.tutorials-intro {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 40px;
  margin-bottom: 56px;
}
.tutorials-copy { max-width: 500px; display: flex; flex-direction: column; gap: 16px; }
.eyebrow {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 14px;
  line-height: 18px;
  color: var(--c-accent);
}
.section-title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 36px;
  line-height: 1.25;
  color: var(--c-text);
}
.section-desc {
  margin: 0;
  font-size: 16px;
  line-height: 1.63;
  color: var(--c-text-2);
}
.community-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  font-size: 14px;
  line-height: 17px;
  color: var(--c-accent);
  white-space: nowrap;
  margin-top: 2px;
}
.community-link:hover { text-decoration: underline; }

.video-player {
  position: relative;
  width: 100%;
  border-radius: 24px;
  overflow: hidden;
  background: var(--c-ink);
  aspect-ratio: 20 / 9;           /* 设计 1200x540 */
  margin-bottom: 56px;
}
.video-player img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.play-button {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: var(--c-white);
  border: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 8px 30px rgba(0,0,0,.18);
  transition: transform .15s ease;
}
.play-button:hover { transform: translate(-50%, -50%) scale(1.05); }
.play-button svg { margin-left: 4px; }

.cards-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.tutorial-card {
  display: flex;
  align-items: center;
  gap: 16px;
  background: var(--c-bg-light);
  border-radius: 16px;
  padding: 16px;
}
.tutorial-card img {
  width: 112px;
  height: 70px;
  border-radius: 8px;
  object-fit: cover;
  flex-shrink: 0;
}
.card-body { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
.card-title {
  margin: 0;
  font-size: 15px;
  font-weight: 600;
  line-height: 18px;
  color: var(--c-text);
}
.duration {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  line-height: 15px;
  color: var(--c-text-2);
}
.duration svg { flex-shrink: 0; }

/* ---------- CTA ---------- */
.cta {
  background: var(--c-bg-light);
  padding: 120px 0;
}
.cta-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 40px;
}
.cta-copy {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  max-width: 800px;
}
.cta-title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2rem, 4vw, 40px);  /* 设计值 40px */
  line-height: 1.25;
  text-align: center;
  color: var(--c-text);
}
.cta-subtitle {
  margin: 0;
  font-size: 16px;
  line-height: 1.2;
  text-align: center;
  color: var(--c-text-2);
}
.cta-actions {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}
.cta-meta {
  font-size: 12px;
  line-height: 15px;
  color: var(--c-text-2);
  text-align: center;
}

/* ---------- 页脚 ---------- */
.footer {
  background: var(--c-ink);
  color: var(--c-white);
  padding: 80px 0 64px;
}
.footer-top {
  display: flex;
  justify-content: space-between;
  gap: 48px;
  margin-bottom: 48px;
}
.footer-brand { max-width: 360px; display: flex; flex-direction: column; gap: 16px; }
.footer-brand img {
  width: 102px;
  height: 19px;
  object-fit: contain;
}
.footer-brand p {
  margin: 0;
  font-size: 13px;
  line-height: 1.69;
  color: var(--c-text-2);
}
.footer-links {
  display: flex;
  gap: 64px;
}
.footer-col {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.footer-col h4 {
  margin: 0;
  font-size: 14px;
  font-weight: 600;
  line-height: 17px;
  color: var(--c-border);
}
.footer-col a {
  font-size: 13px;
  line-height: 16px;
  color: var(--c-text-2);
  transition: color .15s ease;
}
.footer-col a:hover { color: var(--c-white); }
.footer-divider {
  height: 1px;
  background: rgba(255,255,255,.08);
  margin-bottom: 48px;
}
.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
.footer-copy {
  margin: 0;
  font-size: 12px;
  line-height: 15px;
  color: var(--c-text-2);
}
.footer-meta {
  display: flex;
  align-items: center;
  gap: 24px;
}
.footer-meta a {
  font-size: 12px;
  line-height: 15px;
  color: var(--c-text-2);
  transition: color .15s ease;
}
.footer-meta a:hover { color: var(--c-white); }

/* ---------- 响应式 ---------- */
@media (max-width: 1024px) {
  .cards-row { grid-template-columns: repeat(2, 1fr); }
  .footer-top { flex-direction: column; }
}
@media (max-width: 720px) {
  .container { padding-left: 24px; padding-right: 24px; }
  .nav-inner { grid-template-columns: 1fr auto; }
  .nav-badge { display: none; }
  .nav-toggle { display: flex; }
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
    background: var(--c-white);
    border-bottom: 1px solid var(--c-border);
    padding: 12px 40px 20px;
  }
  .nav-links.is-open { display: flex; }
  .nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
  .nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
  .nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

  .hero { padding: 56px 0 72px; }
  .hero-subtitle { font-size: 18px; }
  .cards-row { grid-template-columns: 1fr; }
  .tutorials { padding: 72px 0; }
  .tutorials-intro { flex-direction: column; align-items: flex-start; gap: 20px; }
  .cta { padding: 72px 0; }
  .footer { padding: 56px 0 40px; }
  .footer-bottom { flex-direction: column; align-items: flex-start; gap: 16px; }
  .footer-links { flex-wrap: wrap; gap: 40px; }
}