:root {
  --bg: #f6f8fb;
  --surface: #ffffff;
  --surface-soft: #eef5f3;
  --ink: #1e293b;
  --muted: #64748b;
  --line: #dbe4ee;
  --blue: #2458a4;
  --teal: #0f766e;
  --orange: #e5682d;
  --warn-bg: #fff4ed;
  --shadow: 0 18px 44px rgba(30, 41, 59, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans CN", sans-serif;
  font-size: 16px;
  line-height: 1.7;
}

a {
  color: inherit;
}

.layout {
  display: grid;
  grid-template-columns: 248px minmax(0, 1120px);
  justify-content: center;
  width: min(100%, 1368px);
  min-height: 100vh;
  margin: 0 auto;
}

.sidebar {
  position: sticky;
  top: 0;
  align-self: start;
  height: 100vh;
  padding: 28px 22px;
  border-left: 1px solid var(--line);
  border-right: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(14px);
}

.brand {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 12px;
  padding-bottom: 22px;
  border-bottom: 1px solid var(--line);
  text-align: center;
}

.brand-mark {
  display: block;
  width: 56px;
  height: 56px;
  border-radius: 12px;
  object-fit: cover;
}

.brand strong,
.brand span {
  display: block;
}

.brand strong {
  font-size: 17px;
  line-height: 1.3;
}

.brand span {
  margin-top: 2px;
  color: var(--muted);
  font-size: 13px;
}

.nav-list {
  display: grid;
  gap: 6px;
  margin-top: 22px;
}

.nav-list a {
  border-radius: 8px;
  padding: 9px 11px;
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  font-weight: 700;
  text-align: center;
}

.nav-list a:hover,
.nav-list a.is-active {
  background: var(--surface-soft);
  color: var(--teal);
}

.content {
  width: min(100%, 1120px);
  margin: 0 auto;
  padding: 34px 28px 72px;
}

.page-header {
  padding: 14px 0 22px;
  text-align: center;
}

.kicker,
.eyebrow {
  margin: 0 0 8px;
  color: var(--teal);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 12px;
  font-size: clamp(30px, 4vw, 48px);
  line-height: 1.12;
  letter-spacing: 0;
}

.summary {
  max-width: 820px;
  margin-right: auto;
  margin-bottom: 20px;
  margin-left: auto;
  color: var(--muted);
  font-size: 17px;
}

.entry-grid {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 10px;
  max-width: 760px;
  margin-right: auto;
  margin-left: auto;
}

.entry-grid a {
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--blue);
  text-align: center;
  text-decoration: none;
  font-weight: 800;
  line-height: 44px;
}

.entry-grid a:hover {
  border-color: rgba(15, 118, 110, 0.45);
  color: var(--teal);
}

.module {
  padding-top: 28px;
  scroll-margin-top: 20px;
}

.module-head {
  padding: 26px 0 10px;
  border-top: 2px solid var(--line);
  text-align: center;
}

.module-head h2 {
  margin-bottom: 8px;
  color: var(--ink);
  font-size: 26px;
  line-height: 1.25;
  letter-spacing: 0;
}

.module-head p:last-child {
  max-width: 760px;
  margin-right: auto;
  margin-bottom: 0;
  margin-left: auto;
  color: var(--muted);
}

.feature-card {
  display: grid;
  grid-template-columns: minmax(220px, 310px) minmax(0, 1fr);
  gap: 24px;
  align-items: start;
  margin: 18px 0;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.shot {
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #eef2f7;
}

.shot img {
  display: block;
  width: 100%;
  height: auto;
  cursor: zoom-in;
}

.feature-copy {
  min-width: 0;
  padding: 4px 2px 0;
}

.step-index {
  display: inline-flex;
  align-items: center;
  height: 28px;
  margin-bottom: 10px;
  padding: 0 10px;
  border-radius: 999px;
  background: #edf6ff;
  color: var(--blue);
  font-size: 13px;
  font-weight: 900;
}

.feature-copy h3 {
  margin-bottom: 8px;
  font-size: 21px;
  line-height: 1.35;
  letter-spacing: 0;
}

.feature-copy p {
  margin-bottom: 8px;
  color: var(--ink);
}

.feature-copy ul {
  margin: 8px 0 0;
  padding-left: 20px;
  color: var(--muted);
}

.feature-copy li {
  margin: 4px 0;
}

.warning {
  margin-top: 12px;
  padding: 10px 12px;
  border-left: 4px solid var(--orange);
  border-radius: 6px;
  background: var(--warn-bg);
  color: #7a3c1b;
}

.footer {
  margin-top: 42px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
  text-align: center;
}

.lightbox {
  position: fixed;
  inset: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 26px;
  background: rgba(15, 23, 42, 0.82);
}

.lightbox[hidden] {
  display: none;
}

.lightbox-panel {
  position: relative;
  display: flex;
  width: min(100%, 1100px);
  max-height: 92vh;
  flex-direction: column;
  align-items: center;
  gap: 10px;
}

.lightbox-image {
  display: block;
  max-width: 100%;
  max-height: calc(92vh - 50px);
  border-radius: 8px;
  background: #ffffff;
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.32);
}

.lightbox-caption {
  margin: 0;
  color: #ffffff;
  font-size: 14px;
  text-align: center;
}

.lightbox-close {
  position: absolute;
  top: -14px;
  right: -14px;
  width: 40px;
  height: 40px;
  border: 0;
  border-radius: 999px;
  background: #ffffff;
  color: var(--ink);
  font-size: 28px;
  line-height: 1;
  cursor: pointer;
  box-shadow: 0 14px 28px rgba(0, 0, 0, 0.22);
}

@media (max-width: 980px) {
  .layout {
    display: block;
  }

  .sidebar {
    position: relative;
    height: auto;
    padding: 18px;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .nav-list {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .content {
    padding: 28px 18px 64px;
  }
}

@media (max-width: 740px) {
  .entry-grid,
  .nav-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .feature-card {
    grid-template-columns: 1fr;
    gap: 16px;
    padding: 14px;
  }

  .shot {
    width: min(100%, 360px);
    margin-right: auto;
    margin-left: auto;
  }
}

@media (max-width: 480px) {
  body {
    font-size: 15px;
  }

  .content {
    padding: 22px 14px 56px;
  }

  .brand-mark {
    width: 48px;
    height: 48px;
  }

  .entry-grid,
  .nav-list {
    grid-template-columns: 1fr;
  }

  .module-head h2 {
    font-size: 22px;
  }

  .feature-copy h3 {
    font-size: 19px;
  }

  .lightbox {
    padding: 12px;
  }

  .lightbox-close {
    top: 8px;
    right: 8px;
  }
}