/* =========================================================================
   Vertiport Website — shared stylesheet
   Visual reference: sample.htm (DLR Institute of Communications & Navigation)
   Theme color: #005F85
   ========================================================================= */

:root {
  --theme: #005F85;
  --theme-dark: #004a68;
  --theme-light: #e8f1f5;
  --ink: #1d1d1b;
  --ink-soft: #4a4a48;
  --line: #e2e2e0;
  --bg: #ffffff;
  --bg-soft: #f6f8f9;
  --maxw: 1100px;
  --radius: 6px;
  --shadow: 0 1px 4px rgba(0, 0, 0, 0.08);
  --font: "Segoe UI", "Helvetica Neue", Arial, system-ui, sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--theme); text-decoration: none; }
a:hover { text-decoration: underline; }

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

/* ---------- Top utility bar ---------- */
.topbar {
  background: var(--theme);
  color: #fff;
  font-size: 13px;
}
.topbar .inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 6px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
}
.topbar a { color: #fff; opacity: 0.9; }
.topbar a:hover { opacity: 1; }
.topbar .links { display: flex; gap: 18px; }

/* ---------- Header ---------- */
.site-header {
  border-bottom: 1px solid var(--line);
  background: #fff;
}
.site-header .inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 18px 20px;
  display: flex;
  align-items: center;
  gap: 18px;
}
.site-header .logo {
  display: flex;
  align-items: center;
  gap: 14px;
}
.site-header .logo img { width: 56px; height: auto; }
.site-header .logo .title { line-height: 1.2; }
.site-header .logo .title .l1 { font-size: 15px; font-weight: 600; color: var(--ink); }
.site-header .logo .title .l2 { font-size: 15px; font-weight: 600; color: var(--ink); }
.site-header .logo .title .l3 { font-size: 12px; color: var(--ink-soft); margin-top: 2px; }

.site-header .spacer { flex: 1; }

.site-header .brand {
  font-size: 13px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--theme);
  font-weight: 700;
}

/* ---------- Navigation ---------- */
.site-nav {
  background: var(--bg-soft);
  border-bottom: 1px solid var(--line);
}
.site-nav .inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}
.site-nav a {
  display: inline-block;
  padding: 12px 14px;
  font-size: 14px;
  color: var(--ink-soft);
  border-bottom: 3px solid transparent;
}
.site-nav a:hover { color: var(--theme); text-decoration: none; }
.site-nav a.active {
  color: var(--theme);
  font-weight: 600;
  border-bottom-color: var(--theme);
}

/* ---------- Main content ---------- */
main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 40px 20px 64px;
}

.page-title {
  font-size: 34px;
  line-height: 1.2;
  margin: 0 0 8px;
  color: var(--ink);
  font-weight: 700;
}
.page-subtitle {
  font-size: 18px;
  color: var(--ink-soft);
  margin: 0 0 32px;
}

.section { margin-bottom: 40px; }

h2 {
  font-size: 24px;
  margin: 0 0 14px;
  color: var(--ink);
  padding-bottom: 8px;
  border-bottom: 2px solid var(--theme);
  display: inline-block;
}
h3 { font-size: 19px; margin: 0 0 10px; color: var(--ink); }

p { margin: 0 0 16px; }

/* ---------- Figures ---------- */
figure {
  margin: 0 0 28px;
  background: var(--bg-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}
figure img { width: 100%; }
figcaption {
  padding: 12px 16px;
  font-size: 14px;
  color: var(--ink-soft);
  background: #fff;
  border-top: 1px solid var(--line);
}
figcaption .credit {
  display: block;
  margin-top: 6px;
  font-size: 12px;
  color: #8a8a88;
}

/* ---------- Feature list ---------- */
.feature-list {
  list-style: none;
  padding: 0;
  margin: 0 0 8px;
}
.feature-list li {
  position: relative;
  padding: 10px 0 10px 30px;
  border-bottom: 1px solid var(--line);
}
.feature-list li:last-child { border-bottom: none; }
.feature-list li::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 16px;
  width: 10px;
  height: 10px;
  background: var(--theme);
  border-radius: 2px;
}

/* ---------- Link cards (mainpage) ---------- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 20px;
  margin-top: 8px;
}
.card {
  display: block;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.card:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.12);
  text-decoration: none;
}
.card .thumb {
  aspect-ratio: 16 / 10;
  overflow: hidden;
  background: var(--bg-soft);
}
.card .thumb img { width: 100%; height: 100%; object-fit: cover; }
.card .body { padding: 14px 16px; }
.card .body .name {
  font-size: 16px;
  font-weight: 600;
  color: var(--ink);
  margin-bottom: 4px;
}
.card .body .desc { font-size: 13px; color: var(--ink-soft); }

/* ---------- External link list ---------- */
.ext-links { list-style: none; padding: 0; margin: 0; }
.ext-links li {
  padding: 10px 0 10px 28px;
  position: relative;
  border-bottom: 1px solid var(--line);
}
.ext-links li:last-child { border-bottom: none; }
.ext-links li::before {
  content: "\2197";
  position: absolute;
  left: 4px;
  color: var(--theme);
  font-size: 15px;
}

/* ---------- Paper callout ---------- */
.paper-card {
  display: flex;
  gap: 16px;
  align-items: flex-start;
  background: var(--theme-light);
  border: 1px solid #cfe0e8;
  border-left: 4px solid var(--theme);
  border-radius: var(--radius);
  padding: 18px 20px;
  margin: 8px 0;
}
.paper-card .icon {
  flex: 0 0 auto;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--theme);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
}
.paper-card .meta { font-size: 14px; color: var(--ink-soft); margin-top: 6px; }
.paper-card .title { font-size: 16px; font-weight: 600; color: var(--ink); }

/* ---------- Placeholder / coming soon ---------- */
.coming-soon {
  background: var(--bg-soft);
  border: 1px dashed var(--line);
  border-radius: var(--radius);
  padding: 40px;
  text-align: center;
  color: var(--ink-soft);
  font-size: 16px;
}

/* ---------- Footer ---------- */
.site-footer {
  background: var(--ink);
  color: #cfcfcd;
  margin-top: 40px;
}
.site-footer .inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 36px 20px;
  display: flex;
  flex-wrap: wrap;
  gap: 32px;
  justify-content: space-between;
}
.site-footer .col h4 {
  color: #fff;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin: 0 0 10px;
}
.site-footer .col p, .site-footer .col a {
  font-size: 14px;
  color: #cfcfcd;
  margin: 0 0 6px;
}
.site-footer .col a:hover { color: #fff; }
.site-footer .brand {
  display: flex;
  align-items: center;
  gap: 12px;
}
.site-footer .brand img { width: 44px; height: auto; filter: brightness(0) invert(1); }
.site-footer .brand .t { font-size: 14px; line-height: 1.3; }
.site-footer .bottom {
  border-top: 1px solid #3a3a38;
  padding: 14px 20px;
  text-align: center;
  font-size: 12px;
  color: #8a8a88;
}

/* ---------- Responsive ---------- */
@media (max-width: 640px) {
  .page-title { font-size: 26px; }
  .site-header .logo .title .l1,
  .site-header .logo .title .l2 { font-size: 13px; }
  .topbar .links { display: none; }
}