* { box-sizing: border-box; }

:root {
  --ink: #17212b;
  --muted: #5f6f7d;
  --line: #dfe7ed;
  --paper: #ffffff;
  --soft: #f5f8fa;
  --teal: #087f8c;
  --mint: #18a999;
  --navy: #11324d;
  --coral: #ee6c4d;
  --gold: #f5b942;
  --blue: #4b7bec;
  --shadow: 0 18px 45px rgba(23, 33, 43, .10);
}

body {
  margin: 0;
  font-family: "Segoe UI", Tahoma, Arial, sans-serif;
  color: var(--ink);
  background: var(--soft);
  line-height: 1.75;
}

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

.wrap {
  width: min(1160px, calc(100% - 32px));
  margin: auto;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255,255,255,.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(10px);
}

.nav {
  min-height: 70px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 800;
}

.brand-mark {
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  color: #fff;
  background: linear-gradient(135deg, var(--teal), var(--mint));
  border-radius: 8px;
  box-shadow: 0 10px 24px rgba(8,127,140,.22);
}

.nav a.back {
  color: var(--teal);
  font-weight: 800;
  padding: 9px 12px;
  border-radius: 8px;
  background: #e9f7f5;
}

.hero {
  color: white;
  background:
    linear-gradient(90deg, rgba(17, 50, 77, .96), rgba(8, 127, 140, .88)),
    var(--hero-image) center top / cover;
}

.hero-inner {
  min-height: 330px;
  display: grid;
  align-items: center;
  padding: 46px 0;
}

.crumb {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  color: rgba(255,255,255,.74);
  font-size: 14px;
  margin-bottom: 16px;
}

h1 {
  margin: 0 0 12px;
  font-size: clamp(34px, 5vw, 58px);
  line-height: 1.1;
}

.hero p {
  max-width: 760px;
  margin: 0;
  color: rgba(255,255,255,.86);
  font-size: 18px;
}

.layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 24px;
  align-items: start;
  padding: 34px 0 60px;
}

.toc {
  position: sticky;
  top: 92px;
  background: white;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px;
  box-shadow: 0 8px 22px rgba(23,33,43,.05);
}

.toc h2 {
  margin: 0 0 12px;
  font-size: 18px;
}

.toc a {
  display: block;
  padding: 10px 8px;
  border-radius: 8px;
  color: var(--muted);
  font-size: 14px;
}

.toc a:hover {
  background: #eef7f8;
  color: var(--teal);
}

.article {
  display: grid;
  gap: 18px;
}

.panel {
  background: white;
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 8px 22px rgba(23,33,43,.05);
  overflow: hidden;
}

.panel-body { padding: 24px; }

.panel h2 {
  margin: 0 0 12px;
  font-size: 28px;
  line-height: 1.25;
}

.panel h3 {
  margin: 0 0 8px;
  font-size: 20px;
}

.panel p {
  margin: 0 0 14px;
  color: var(--muted);
}

.screenshot {
  border-bottom: 1px solid var(--line);
  background: #0f2637;
}

.screenshot img {
  width: 100%;
  max-height: 430px;
  object-fit: cover;
  object-position: top;
}

.steps {
  counter-reset: step;
  display: grid;
  gap: 12px;
  padding: 0;
  margin: 0;
  list-style: none;
}

.steps li {
  counter-increment: step;
  display: grid;
  grid-template-columns: 44px 1fr;
  gap: 12px;
  align-items: start;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfdfe;
}

.steps li::before {
  content: counter(step);
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: #e9f7f5;
  color: var(--teal);
  font-weight: 900;
}

.callout {
  padding: 16px;
  border-radius: 8px;
  background: #fff8e6;
  border: 1px solid #ffe1a6;
  color: #5d4a14;
}

.files {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.file-card {
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfdfe;
}

.file-card strong {
  display: block;
  margin-bottom: 4px;
}

.file-card span {
  color: var(--muted);
  font-size: 14px;
}

.faq details {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfdfe;
  padding: 14px 16px;
}

.faq details + details { margin-top: 10px; }
.faq summary { cursor: pointer; font-weight: 800; }
.faq p { margin: 10px 0 0; }

.next-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.next-grid a {
  padding: 16px;
  background: white;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--teal);
  font-weight: 800;
}

footer {
  padding: 28px 0;
  background: #0b1d2d;
  color: rgba(255,255,255,.72);
  font-size: 14px;
}

@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
  .toc { position: static; }
  .files, .next-grid { grid-template-columns: 1fr; }
  .nav { align-items: start; flex-direction: column; padding: 14px 0; }
}

@media (max-width: 560px) {
  .wrap { width: min(100% - 22px, 1160px); }
  .panel-body { padding: 18px; }
  .steps li { grid-template-columns: 1fr; }
}