:root {
  color-scheme: light;
  --bg: #f5f7fa;
  --surface: #ffffff;
  --surface-soft: #eef3f8;
  --ink: #202733;
  --muted: #667085;
  --line: #d7dee8;
  --blue: #315f91;
  --blue-deep: #244866;
  --amber: #b46a21;
  --green: #2f7257;
  --shadow: 0 18px 45px rgba(32, 39, 51, 0.10);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.55;
}

button,
input {
  font: inherit;
}

.app-shell {
  display: grid;
  grid-template-columns: 320px minmax(0, 1fr);
  min-height: 100vh;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  overflow: auto;
  border-right: 1px solid var(--line);
  background: #fbfcfe;
  padding: 22px 18px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 22px;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 8px;
  background: var(--blue-deep);
  color: white;
  font-weight: 700;
}

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

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

.search {
  display: block;
  margin-bottom: 18px;
}

.search span {
  display: block;
  margin-bottom: 6px;
  color: var(--muted);
  font-size: 12px;
  text-transform: uppercase;
}

.search input {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px 12px;
  background: white;
  color: var(--ink);
}

.search input:focus {
  outline: 2px solid rgba(49, 95, 145, 0.25);
  border-color: var(--blue);
}

nav {
  display: grid;
  gap: 4px;
}

nav a {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 12px;
  align-items: center;
  padding: 8px 10px;
  border-radius: 8px;
  color: var(--ink);
  text-decoration: none;
  font-size: 14px;
}

nav a span {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

nav a small {
  color: var(--muted);
}

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

.content {
  min-width: 0;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 28px;
  align-items: end;
  padding: 42px clamp(24px, 5vw, 74px) 30px;
  background: linear-gradient(180deg, #ffffff 0%, #f7fafc 100%);
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--amber);
  font-weight: 700;
  text-transform: uppercase;
  font-size: 12px;
}

h1 {
  margin: 0;
  max-width: 780px;
  font-size: 42px;
  line-height: 1.1;
  letter-spacing: 0;
}

.lead {
  max-width: 760px;
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 17px;
}

.hero-meta {
  display: grid;
  gap: 8px;
  min-width: 180px;
  color: var(--blue-deep);
  font-weight: 700;
}

.hero-meta span {
  border-left: 3px solid var(--green);
  padding-left: 10px;
}

.manual {
  width: min(100%, 1040px);
  margin: 0 auto;
  padding: 26px clamp(18px, 4vw, 54px) 70px;
}

.manual-section {
  padding: 30px 0 34px;
  border-bottom: 1px solid var(--line);
  scroll-margin-top: 18px;
}

.manual-section[hidden] {
  display: none;
}

.section-kicker {
  margin-bottom: 8px;
  color: var(--muted);
  font-size: 13px;
}

h2 {
  margin: 12px 0 12px;
  color: var(--blue);
  font-size: 28px;
  line-height: 1.2;
  letter-spacing: 0;
}

p {
  margin: 0 0 12px;
  max-width: 86ch;
}

.toc-line {
  color: var(--blue-deep);
  font-weight: 600;
  margin-bottom: 6px;
}

.step {
  padding-left: 16px;
  border-left: 3px solid rgba(180, 106, 33, 0.45);
}

.figure-grid {
  display: grid;
  gap: 18px;
  margin-top: 18px;
}

figure {
  margin: 0;
}

.image-button {
  display: block;
  width: 100%;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
  background: white;
  box-shadow: var(--shadow);
  cursor: zoom-in;
}

.image-button img {
  display: block;
  width: 100%;
  height: auto;
}

figcaption {
  margin-top: 6px;
  color: var(--muted);
  font-size: 12px;
}

.empty-state {
  margin: 28px clamp(24px, 5vw, 74px) 0;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--muted);
}

.lightbox {
  width: min(94vw, 1180px);
  border: 0;
  border-radius: 8px;
  padding: 18px;
  background: white;
  box-shadow: 0 26px 80px rgba(0, 0, 0, 0.35);
}

.lightbox::backdrop {
  background: rgba(20, 27, 38, 0.72);
}

.lightbox img {
  display: block;
  max-width: 100%;
  max-height: 82vh;
  margin: 0 auto;
}

.dialog-close {
  float: right;
  width: 36px;
  height: 36px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: white;
  color: var(--ink);
  cursor: pointer;
}

@media (max-width: 900px) {
  .app-shell {
    display: block;
  }

  .sidebar {
    position: relative;
    height: auto;
    max-height: 55vh;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

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

  h1 {
    font-size: 34px;
  }
}

@media (max-width: 560px) {
  .sidebar {
    padding: 16px;
  }

  .hero {
    padding: 28px 18px 22px;
  }

  h1 {
    font-size: 30px;
  }

  .lead {
    font-size: 15px;
  }

  h2 {
    font-size: 23px;
  }
}