:root {
  --blue: #1a6fd4;
  --blue-dark: #0d4a9a;
  --blue-light: #e8f3ff;
  --cyan: #2ec4ff;
  --text: #1a1a2e;
  --text-muted: #5a6270;
  --bg: #f5f8fc;
  --white: #ffffff;
  --border: #d8e4f0;
  --radius: 12px;
  --shadow: 0 8px 28px rgba(26, 111, 212, 0.1);
  --max: 1120px;
  --font: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  line-height: 1.75;
  min-height: 100vh;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--blue);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  color: var(--blue-dark);
}

ul,
ol {
  padding-left: 1.25rem;
}

li {
  margin: 0.35rem 0;
}

.container {
  width: min(100% - 2rem, var(--max));
  margin-inline: auto;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  box-shadow: 0 2px 12px rgba(13, 74, 154, 0.06);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: 68px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  color: var(--text);
  font-weight: 700;
  font-size: 1.15rem;
  flex-shrink: 0;
}

.brand img {
  width: 42px;
  height: 42px;
  border-radius: 10px;
  object-fit: cover;
}

.brand span {
  background: linear-gradient(120deg, var(--blue), var(--cyan));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.nav {
  display: flex;
  align-items: center;
  gap: 0.15rem 1.1rem;
  flex-wrap: wrap;
}

.nav a {
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 500;
  padding: 0.35rem 0;
  position: relative;
}

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

.nav a.active::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--blue);
  border-radius: 2px;
}

.menu-toggle {
  display: none;
  border: 1px solid var(--border);
  background: var(--white);
  border-radius: 8px;
  width: 42px;
  height: 42px;
  cursor: pointer;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
}

.menu-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
}

/* Hero */
.hero {
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(ellipse 80% 60% at 20% 20%, rgba(46, 196, 255, 0.25), transparent),
    radial-gradient(ellipse 70% 50% at 85% 10%, rgba(26, 111, 212, 0.2), transparent),
    linear-gradient(165deg, #eef6ff 0%, #f7fbff 45%, #e8f3ff 100%);
  padding: 3.5rem 0 2.5rem;
  border-bottom: 1px solid var(--border);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 2.5rem;
  align-items: center;
}

.hero-badge {
  display: inline-block;
  background: var(--blue-light);
  color: var(--blue-dark);
  font-size: 0.85rem;
  font-weight: 600;
  padding: 0.35rem 0.85rem;
  border-radius: 999px;
  margin-bottom: 1rem;
}

.hero h1 {
  font-size: clamp(1.75rem, 3.2vw, 2.45rem);
  line-height: 1.3;
  margin-bottom: 1rem;
  color: var(--blue-dark);
}

.hero-lead {
  color: var(--text-muted);
  font-size: 1.05rem;
  margin-bottom: 1.5rem;
  max-width: 36em;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.75rem 1.35rem;
  border-radius: 10px;
  font-weight: 600;
  font-size: 0.98rem;
  border: none;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.2s, background 0.2s;
}

.btn-primary {
  background: linear-gradient(135deg, var(--blue), #2a8af0);
  color: var(--white);
  box-shadow: 0 8px 20px rgba(26, 111, 212, 0.28);
}

.btn-primary:hover {
  color: var(--white);
  transform: translateY(-1px);
  box-shadow: 0 10px 24px rgba(26, 111, 212, 0.35);
}

.btn-ghost {
  background: var(--white);
  color: var(--blue-dark);
  border: 1px solid var(--border);
}

.btn-ghost:hover {
  border-color: var(--blue);
  color: var(--blue);
}

.hero-meta {
  font-size: 0.88rem;
  color: var(--text-muted);
}

.hero-visual {
  display: flex;
  justify-content: center;
}

.hero-visual img {
  width: min(280px, 100%);
  border-radius: 28px;
  box-shadow: var(--shadow);
  border: 4px solid var(--white);
}

/* Sections */
.section {
  padding: 3rem 0;
}

.section-alt {
  background: var(--white);
  border-block: 1px solid var(--border);
}

.section-head {
  margin-bottom: 1.75rem;
  max-width: 48rem;
}

.section-head h2 {
  font-size: clamp(1.4rem, 2.4vw, 1.85rem);
  color: var(--blue-dark);
  margin-bottom: 0.55rem;
  line-height: 1.35;
}

.section-head p {
  color: var(--text-muted);
}

.prose h2,
.prose h3 {
  color: var(--blue-dark);
  margin: 1.75rem 0 0.75rem;
  line-height: 1.4;
}

.prose h2 {
  font-size: 1.45rem;
  padding-bottom: 0.4rem;
  border-bottom: 2px solid var(--blue-light);
}

.prose h3 {
  font-size: 1.15rem;
}

.prose p {
  margin: 0.85rem 0;
  color: var(--text);
}

.prose strong {
  color: var(--blue-dark);
}

/* Feature / shot grid */
.shot-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
}

.shot-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 4px 16px rgba(13, 74, 154, 0.05);
  transition: transform 0.2s, box-shadow 0.2s;
}

.shot-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
}

.shot-card img {
  width: 100%;
  aspect-ratio: 9 / 16;
  object-fit: cover;
  object-position: top;
  background: #eef3f9;
}

.shot-card .cap {
  padding: 0.9rem 1rem 1.1rem;
}

.shot-card .cap h3 {
  font-size: 1rem;
  margin-bottom: 0.35rem;
  color: var(--text);
}

.shot-card .cap p {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.6;
}

.shot-row-2 {
  grid-template-columns: repeat(2, 1fr);
}

.shot-wide img {
  aspect-ratio: 9 / 14;
}

/* Steps */
.steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  counter-reset: step;
}

.step {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  position: relative;
}

.step::before {
  counter-increment: step;
  content: counter(step);
  display: inline-flex;
  width: 32px;
  height: 32px;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--blue);
  color: #fff;
  font-weight: 700;
  font-size: 0.9rem;
  margin-bottom: 0.75rem;
}

.step h3 {
  font-size: 1rem;
  margin-bottom: 0.4rem;
}

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

/* FAQ / info blocks */
.info-list {
  display: grid;
  gap: 1rem;
}

.info-item {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.15rem 1.25rem;
}

.info-item h3 {
  font-size: 1.05rem;
  color: var(--blue-dark);
  margin-bottom: 0.45rem;
}

.info-item p {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* TOC */
.toc {
  background: var(--blue-light);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.4rem;
  margin: 1.5rem 0 2rem;
}

.toc h2 {
  font-size: 1.05rem;
  margin-bottom: 0.65rem;
  border: none;
  padding: 0;
}

.toc ol {
  margin: 0;
  columns: 2;
  gap: 1.5rem;
}

.toc a {
  font-weight: 500;
}

/* Page hero (inner) */
.page-hero {
  background: linear-gradient(135deg, #e8f3ff, #f5f9ff);
  border-bottom: 1px solid var(--border);
  padding: 2.25rem 0;
}

.page-hero h1 {
  font-size: clamp(1.5rem, 2.8vw, 2rem);
  color: var(--blue-dark);
  margin-bottom: 0.5rem;
}

.page-hero p {
  color: var(--text-muted);
  max-width: 40rem;
}

.breadcrumb {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.breadcrumb a {
  color: var(--text-muted);
}

.breadcrumb a:hover {
  color: var(--blue);
}

.content-wrap {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  padding: 2.5rem 0 3.5rem;
}

.content-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem 1.5rem;
  box-shadow: 0 4px 18px rgba(13, 74, 154, 0.04);
}

.related {
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border);
}

.related h3 {
  font-size: 1.05rem;
  margin-bottom: 0.75rem;
  color: var(--blue-dark);
}

.related-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.related-links a {
  background: var(--blue-light);
  color: var(--blue-dark);
  padding: 0.4rem 0.85rem;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 500;
}

.related-links a:hover {
  background: var(--blue);
  color: #fff;
}

/* Error pages */
.error-page {
  min-height: 70vh;
  display: flex;
  align-items: center;
  text-align: center;
  padding: 3rem 0;
}

.error-page h1 {
  font-size: 4rem;
  color: var(--blue);
  line-height: 1;
  margin-bottom: 0.5rem;
}

.error-page h2 {
  font-size: 1.4rem;
  margin-bottom: 0.75rem;
}

.error-page p {
  color: var(--text-muted);
  margin-bottom: 1.5rem;
}

/* Footer */
.site-footer {
  background: #0b2f66;
  color: rgba(255, 255, 255, 0.85);
  padding: 2.5rem 0 1.5rem;
  margin-top: auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  margin-bottom: 0.85rem;
}

.footer-brand img {
  width: 40px;
  height: 40px;
  border-radius: 9px;
}

.footer-brand strong {
  color: #fff;
  font-size: 1.1rem;
}

.site-footer p {
  font-size: 0.9rem;
  line-height: 1.7;
  opacity: 0.88;
}

.site-footer h4 {
  color: #fff;
  margin-bottom: 0.85rem;
  font-size: 1rem;
}

.site-footer ul {
  list-style: none;
  padding: 0;
}

.site-footer li {
  margin: 0.45rem 0;
}

.site-footer a {
  color: rgba(255, 255, 255, 0.8);
  font-size: 0.92rem;
}

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

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  padding-top: 1.1rem;
  font-size: 0.85rem;
  opacity: 0.75;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.5rem;
}

/* Utilities */
.mt-2 {
  margin-top: 2rem;
}

.mb-1 {
  margin-bottom: 1rem;
}

.note {
  background: #fff8e8;
  border: 1px solid #f0dfb0;
  border-radius: 10px;
  padding: 1rem 1.15rem;
  color: #6a5420;
  font-size: 0.92rem;
  margin: 1rem 0;
}

.keyword-box {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 1rem 0;
}

.keyword-box span {
  background: var(--blue-light);
  color: var(--blue-dark);
  font-size: 0.82rem;
  padding: 0.3rem 0.7rem;
  border-radius: 6px;
}

/* Mobile */
@media (max-width: 900px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }

  .hero-visual {
    order: -1;
  }

  .hero-visual img {
    width: min(200px, 55vw);
  }

  .shot-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .steps {
    grid-template-columns: repeat(2, 1fr);
  }

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

  .toc ol {
    columns: 1;
  }
}

@media (max-width: 720px) {
  .menu-toggle {
    display: flex;
  }

  .nav {
    display: none;
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: var(--white);
    flex-direction: column;
    align-items: stretch;
    padding: 0.75rem 1rem 1rem;
    border-bottom: 1px solid var(--border);
    box-shadow: 0 10px 24px rgba(0, 0, 0, 0.06);
  }

  .nav.open {
    display: flex;
  }

  .nav a {
    padding: 0.7rem 0.5rem;
    border-bottom: 1px solid var(--border);
  }

  .header-inner {
    position: relative;
  }

  .shot-grid,
  .shot-row-2 {
    grid-template-columns: 1fr;
  }

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

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .section {
    padding: 2.25rem 0;
  }

  .content-card {
    padding: 1.25rem 1rem;
  }

  .hero {
    padding: 2rem 0 1.75rem;
  }
}