:root {
  --bg: #f4f7f8;
  --text: #15222b;
  --muted: #5d6b73;
  --panel: #ffffff;
  --accent: #23495c;
  --accent-light: #dce9ee;
  --border: #d8e2e6;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

.site-header {
  padding: 4rem 8vw;
  background:
    linear-gradient(rgba(21, 34, 43, 0.72), rgba(21, 34, 43, 0.72)),
    url("images/header-placeholder.svg");
  background-size: cover;
  background-position: center;
  color: white;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-size: 0.78rem;
  opacity: 0.85;
}

h1 {
  max-width: 900px;
  font-size: clamp(2.4rem, 6vw, 5rem);
  line-height: 1;
  margin: 0.2rem 0 1rem;
}

.subtitle {
  max-width: 760px;
  font-size: 1.18rem;
  color: #edf5f7;
}

.top-nav {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding: 0.75rem 8vw;
  background: rgba(255, 255, 255, 0.95);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(8px);
}

.top-nav a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 700;
  padding: 0.35rem 0.6rem;
  border-radius: 999px;
}

.top-nav a:hover,
.top-nav a.active {
  background: var(--accent-light);
}

main {
  padding: 2rem 8vw 4rem;
}

.section {
  max-width: 1200px;
  margin: 0 auto 3rem;
  scroll-margin-top: 5rem;
}

.section h2 {
  font-size: clamp(1.8rem, 3vw, 2.6rem);
  border-bottom: 3px solid var(--accent);
  padding-bottom: 0.35rem;
  margin-bottom: 1.2rem;
}

.card-grid,
.gear-grid,
.two-column {
  display: grid;
  gap: 1rem;
}

.card-grid {
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.gear-grid {
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}

.two-column {
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
}

.card,
.two-column > div,
details {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 1.2rem;
  box-shadow: 0 8px 24px rgba(21, 34, 43, 0.06);
}

.card h3,
.two-column h3 {
  margin-top: 0;
}

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

.task-list {
  list-style: none;
  padding-left: 0;
}

.task-list li {
  margin: 0.55rem 0;
}

.task-list input {
  margin-right: 0.5rem;
  transform: scale(1.1);
}

table {
  width: 100%;
  border-collapse: collapse;
  background: white;
}

th,
td {
  border-bottom: 1px solid var(--border);
  padding: 0.7rem;
  text-align: left;
  vertical-align: top;
}

th {
  background: var(--accent-light);
}

details {
  margin-bottom: 1rem;
}

summary {
  cursor: pointer;
  font-weight: 700;
  color: var(--accent);
}

.note {
  color: var(--muted);
}

.link-list {
  display: grid;
  gap: 0.75rem;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.link-list a {
  display: block;
  padding: 1rem;
  background: white;
  color: var(--accent);
  border: 1px solid var(--border);
  border-radius: 12px;
  text-decoration: none;
  font-weight: 700;
}

.link-list a:hover {
  background: var(--accent-light);
}

.page-links {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
}

.page-links a {
  display: block;
  padding: 1.1rem;
  background: white;
  color: var(--accent);
  border: 1px solid var(--border);
  border-radius: 14px;
  text-decoration: none;
  font-weight: 700;
  box-shadow: 0 8px 24px rgba(21, 34, 43, 0.06);
}

.page-links a span {
  display: block;
  color: var(--muted);
  font-weight: 400;
  margin-top: 0.35rem;
}

#backToTop {
  display: none;
  position: fixed;
  right: 1rem;
  bottom: 1rem;
  border: none;
  border-radius: 50%;
  width: 46px;
  height: 46px;
  background: var(--accent);
  color: white;
  font-size: 1.4rem;
  cursor: pointer;
  box-shadow: 0 8px 24px rgba(21, 34, 43, 0.25);
}

footer {
  text-align: center;
  padding: 2rem;
  background: #e8eff2;
  color: var(--muted);
}

@media (max-width: 700px) {
  .site-header,
  .top-nav,
  main {
    padding-left: 1rem;
    padding-right: 1rem;
  }

  .top-nav {
    position: static;
  }
}