:root {
  --accent: #ff4d4f;
  --accent-deep: #d9363e;
  --accent-soft: #ffe3e3;
  --ink: #1f1a1a;
  --muted: #6d5d5d;
  --surface: rgba(255, 255, 255, 0.78);
  --surface-strong: #fff8f8;
  --line: rgba(255, 77, 79, 0.16);
  --shadow: 0 24px 80px rgba(120, 28, 33, 0.16);
  --radius-xl: 28px;
  --radius-lg: 22px;
  --radius-md: 16px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "SF Pro Display", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(255, 117, 117, 0.30), transparent 32%),
    radial-gradient(circle at right 20%, rgba(255, 212, 166, 0.55), transparent 26%),
    linear-gradient(180deg, #fff7f6 0%, #fff1ee 52%, #fffdfc 100%);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.42) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.42) 1px, transparent 1px);
  background-size: 32px 32px;
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.6), transparent 80%);
}

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

p,
li {
  line-height: 1.8;
}

.site-shell {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
  padding: 24px 0 56px;
}

.topbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 16px 20px;
  margin-bottom: 24px;
  border: 1px solid rgba(255, 255, 255, 0.6);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.62);
  backdrop-filter: blur(20px);
  box-shadow: 0 18px 60px rgba(123, 42, 42, 0.08);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  border-radius: 14px;
  color: #fff;
  background: linear-gradient(135deg, var(--accent) 0%, #ff7a45 100%);
  box-shadow: 0 14px 28px rgba(255, 77, 79, 0.28);
}

.brand-text {
  font-size: 1.05rem;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.nav a {
  padding: 10px 14px;
  border-radius: 999px;
  color: var(--muted);
  transition: 0.25s ease;
}

.nav a:hover,
.nav a.is-active {
  color: var(--accent-deep);
  background: rgba(255, 77, 79, 0.1);
}

.hero,
.section-split,
.doc-layout,
.faq-grid,
.feature-grid {
  display: grid;
  gap: 20px;
}

.hero {
  grid-template-columns: 1.3fr 0.8fr;
  align-items: center;
  padding: 34px 0 18px;
}

.hero-copy h1,
.page-hero h1 {
  margin: 10px 0 16px;
  font-size: clamp(2.6rem, 5vw, 4.8rem);
  line-height: 1.02;
  letter-spacing: -0.04em;
}

.hero-copy,
.hero-panel,
.page-hero,
.feature-card,
.info-card,
.intro-card,
.contact-card,
.toc-card,
.prose-card,
.faq-card {
  animation: rise-in 0.7s ease both;
}

.hero-panel {
  animation-delay: 0.08s;
}

.feature-card:nth-child(2),
.faq-card:nth-child(2) {
  animation-delay: 0.08s;
}

.feature-card:nth-child(3),
.faq-card:nth-child(3) {
  animation-delay: 0.14s;
}

.hero-text,
.page-hero p,
.muted {
  color: var(--muted);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 28px;
}

.button,
.chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 13px 18px;
  border-radius: 999px;
  font-weight: 700;
  transition: transform 0.25s ease, box-shadow 0.25s ease, background 0.25s ease;
}

.button:hover,
.chip:hover {
  transform: translateY(-2px);
}

.button-primary {
  color: #fff;
  background: linear-gradient(135deg, var(--accent) 0%, #ff7a45 100%);
  box-shadow: 0 16px 32px rgba(255, 77, 79, 0.24);
}

.button-secondary,
.chip {
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.72);
}

.card {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  background: var(--surface);
  backdrop-filter: blur(18px);
  box-shadow: var(--shadow);
}

.glass::after,
.accent-card::after {
  content: "";
  position: absolute;
  inset: auto -30% -45% auto;
  width: 220px;
  height: 220px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(255, 77, 79, 0.24), transparent 68%);
}

.hero-panel,
.page-hero,
.info-card,
.intro-card,
.contact-card,
.toc-card,
.prose-card,
.faq-card,
.feature-card {
  padding: 28px;
}

.panel-badge,
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent-deep);
}

.color-token {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  margin: 18px 0 12px;
  padding: 12px 16px;
  border-radius: 18px;
  background: var(--surface-strong);
}

.color-dot {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 6px rgba(255, 77, 79, 0.12);
}

.section {
  margin-top: 28px;
}

.section-heading {
  margin-bottom: 18px;
}

.section-heading h2,
.info-card h2,
.intro-card h2,
.contact-card h2,
.toc-card h2,
.feature-card h3,
.faq-card h3,
.prose-card h2,
.prose-card h3 {
  margin: 10px 0 0;
}

.feature-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.feature-index {
  display: inline-block;
  margin-bottom: 18px;
  font-size: 0.9rem;
  font-weight: 800;
  color: var(--accent-deep);
}

.section-split {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.detail-list {
  list-style: none;
  padding: 0;
  margin: 22px 0 0;
}

.detail-list li {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  padding: 14px 0;
  border-bottom: 1px solid rgba(255, 77, 79, 0.1);
}

.detail-list span {
  color: var(--muted);
}

.chip-group {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 18px 0 20px;
}

.page-hero {
  padding: 34px;
}

.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 18px;
  color: var(--muted);
}

.doc-layout {
  grid-template-columns: 280px minmax(0, 1fr);
  margin-top: 24px;
}

.toc-card {
  position: sticky;
  top: 24px;
  align-self: start;
}

.toc-card a {
  display: block;
  padding: 12px 0;
  color: var(--muted);
  border-bottom: 1px solid rgba(255, 77, 79, 0.1);
}

.toc-card a:hover {
  color: var(--accent-deep);
}

.prose-card section + section {
  margin-top: 26px;
}

.prose-card ul {
  padding-left: 20px;
}

.faq-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

@keyframes rise-in {
  from {
    opacity: 0;
    transform: translateY(18px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 920px) {
  .topbar,
  .hero,
  .section-split,
  .doc-layout,
  .feature-grid,
  .faq-grid {
    grid-template-columns: 1fr;
  }

  .topbar {
    border-radius: 28px;
  }

  .toc-card {
    position: static;
  }
}

@media (max-width: 640px) {
  .site-shell {
    width: min(100% - 20px, 1180px);
    padding-top: 12px;
  }

  .topbar {
    padding: 16px;
  }

  .nav {
    width: 100%;
  }

  .nav a {
    flex: 1 1 calc(50% - 10px);
    text-align: center;
  }

  .hero-panel,
  .page-hero,
  .info-card,
  .intro-card,
  .contact-card,
  .toc-card,
  .prose-card,
  .faq-card,
  .feature-card {
    padding: 22px;
  }

  .detail-list li {
    flex-direction: column;
    gap: 6px;
  }
}