/* IEEE ICRA–inspired project page: navy header, light body, RAS blue accents */

:root {
  --ieee-navy: #00274d;
  --ieee-navy-mid: #0a3a5c;
  --ras-blue: #0077c8;
  --ras-blue-dark: #005a96;
  --accent-teal: #00a3a0;
  --accent-gold: #c5a000;
  --bg-page: #e8edf2;
  --bg-card: #ffffff;
  --bg-code: #f0f4f8;
  --text: #1b2836;
  --text-muted: #4a5f72;
  --border: #c5d0dc;
  --shadow: 0 2px 8px rgba(0, 39, 77, 0.07);
  --shadow-lg: 0 8px 32px rgba(0, 39, 77, 0.1);
  --radius: 6px;
  --font-sans: "Source Sans 3", "Segoe UI", system-ui, sans-serif;
  --font-serif: "Source Serif 4", "Georgia", serif;
  --font-mono: "JetBrains Mono", "Consolas", monospace;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-serif);
  font-size: 1.05rem;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg-page);
  background-image:
    linear-gradient(180deg, rgba(255, 255, 255, 0.5) 0%, transparent 120px),
    radial-gradient(ellipse 100% 60% at 50% 0%, rgba(0, 119, 200, 0.06), transparent 55%);
}

a {
  color: var(--ras-blue-dark);
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}

a:hover {
  color: var(--ieee-navy);
}

/* ——— Conference chrome (ICRA / IEEE RAS style) ——— */

.icra-topbar {
  background: linear-gradient(135deg, var(--ieee-navy) 0%, var(--ieee-navy-mid) 55%, #063b5c 100%);
  color: #fff;
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  letter-spacing: 0.04em;
  padding: 0.65rem 1.5rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.15);
}

.icra-topbar__brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.icra-topbar__brand svg {
  flex-shrink: 0;
  opacity: 0.95;
}

.icra-topbar__meta {
  font-weight: 400;
  opacity: 0.88;
  font-size: 0.78rem;
}

.icra-topbar a {
  color: #b8d9f0;
  text-decoration: none;
}

.icra-topbar a:hover {
  color: #fff;
  text-decoration: underline;
}

/* Thin accent ribbon (common on RAS conference microsites) */
.conf-ribbon {
  height: 5px;
  background: linear-gradient(
    90deg,
    var(--ras-blue) 0%,
    var(--accent-teal) 34%,
    #5a9fd4 66%,
    var(--accent-gold) 100%
  );
}

/* Hero */
.hero-wrap {
  max-width: 58rem;
  margin: 0 auto;
  padding: 2rem 1.5rem 1.5rem;
}

.hero-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  border: 1px solid rgba(0, 74, 120, 0.12);
  overflow: hidden;
  position: relative;
}

.hero-card::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 5px;
  background: linear-gradient(180deg, var(--ras-blue), var(--accent-teal));
}

.hero-card__inner {
  padding: 2rem 2rem 2rem 2.35rem;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 1.5rem 2rem;
  align-items: start;
}

@media (max-width: 640px) {
  .hero-card__inner {
    grid-template-columns: 1fr;
  }
}

.hero-year {
  font-family: var(--font-sans);
  font-weight: 700;
  font-size: 2.75rem;
  line-height: 1;
  color: var(--ras-blue);
  letter-spacing: -0.03em;
  padding: 0.35rem 0.85rem;
  background: linear-gradient(145deg, #f0f7fc 0%, #e2eef6 100%);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  text-align: center;
  min-width: 5.5rem;
}

.hero-body .badge {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ras-blue-dark);
  margin-bottom: 0.5rem;
}

.hero-body h1 {
  font-size: clamp(1.45rem, 3.5vw, 2.05rem);
  font-weight: 600;
  line-height: 1.25;
  margin: 0 0 0.75rem;
  color: var(--ieee-navy);
  letter-spacing: -0.02em;
}

.subtitle {
  color: var(--text-muted);
  font-size: 1.02rem;
  margin: 0 0 1rem;
  max-width: 46em;
}

.conf-venue {
  font-family: var(--font-sans);
  font-size: 0.875rem;
  color: var(--text-muted);
  margin: 0 0 1rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}

.conf-venue strong {
  color: var(--text);
  font-weight: 600;
}

.meta {
  font-size: 0.95rem;
  color: var(--text-muted);
}

.meta strong {
  color: var(--text);
  font-weight: 600;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 1.25rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  font-weight: 600;
  padding: 0.55rem 1.1rem;
  border-radius: 4px;
  border: 1px solid var(--border);
  background: #fff;
  color: var(--ieee-navy);
  text-decoration: none;
  box-shadow: 0 1px 2px rgba(0, 39, 77, 0.06);
  transition: background 0.15s, border-color 0.15s, box-shadow 0.15s;
}

.btn:hover {
  border-color: var(--ras-blue);
  color: var(--ras-blue-dark);
  box-shadow: var(--shadow);
}

.btn-primary {
  background: linear-gradient(180deg, var(--ras-blue) 0%, var(--ras-blue-dark) 100%);
  border-color: var(--ras-blue-dark);
  color: #fff;
}

.btn-primary:hover {
  color: #fff;
  filter: brightness(1.06);
  border-color: var(--ieee-navy);
}

/* Main column */
.wrap {
  max-width: 58rem;
  margin: 0 auto;
  padding: 0 1.5rem 3.5rem;
}

nav.toc {
  margin: 0 0 1.75rem;
  padding: 1.15rem 1.35rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  font-family: var(--font-sans);
}

nav.toc h2 {
  font-size: 0.75rem;
  margin: 0 0 0.85rem;
  color: var(--ras-blue-dark);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

nav.toc ol {
  margin: 0;
  padding-left: 1.35rem;
  color: var(--text-muted);
  font-size: 0.92rem;
}

nav.toc a {
  color: var(--ieee-navy);
  font-weight: 500;
}

nav.toc a:hover {
  color: var(--ras-blue);
}

section {
  padding: 1.75rem 1.5rem;
  margin-bottom: 1.25rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

section h2 {
  font-family: var(--font-sans);
  font-size: 1.2rem;
  font-weight: 700;
  margin: 0 0 1rem;
  padding-bottom: 0.65rem;
  border-bottom: 2px solid var(--ras-blue);
  color: var(--ieee-navy);
  letter-spacing: -0.02em;
}

section h3 {
  font-family: var(--font-sans);
  font-size: 1.02rem;
  font-weight: 600;
  margin: 1.35rem 0 0.6rem;
  color: var(--ieee-navy);
}

p {
  margin: 0 0 1rem;
}

ul,
ol {
  margin: 0 0 1rem;
  padding-left: 1.35rem;
}

li {
  margin-bottom: 0.4rem;
}

code,
kbd {
  font-family: var(--font-mono);
  font-size: 0.86em;
  background: var(--bg-code);
  padding: 0.12em 0.4em;
  border-radius: 4px;
  border: 1px solid #d8e0ea;
  color: #0d2c45;
}

pre {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.55;
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-left: 4px solid var(--ras-blue);
  border-radius: var(--radius);
  padding: 1rem 1.15rem;
  overflow-x: auto;
}

pre code {
  padding: 0;
  border: none;
  background: none;
}

.video-frame {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #0a1628;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  margin: 1rem 0 0;
  box-shadow: var(--shadow);
}

.video-frame iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  margin: 1rem 0;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
}

th,
td {
  text-align: left;
  padding: 0.65rem 0.85rem;
  border-bottom: 1px solid var(--border);
}

th {
  background: linear-gradient(180deg, #f2f6fa 0%, #e8eef4 100%);
  font-weight: 700;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--ieee-navy);
}

tbody tr:nth-child(even) {
  background: #fafcfd;
}

tbody tr:last-child td {
  border-bottom: none;
}

td code {
  white-space: nowrap;
}

.cite {
  font-size: 0.92rem;
  color: var(--text-muted);
  padding: 0.85rem 1rem;
  border-left: 4px solid var(--accent-teal);
  margin: 1rem 0;
  background: #f6fafb;
  border-radius: 0 var(--radius) var(--radius) 0;
}

.footnote {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-top: 1.25rem;
  padding-top: 1rem;
  border-top: 1px dashed var(--border);
}

.site-footer {
  margin-top: 0.5rem;
  padding: 1.35rem 1.5rem;
  background: linear-gradient(180deg, #f4f7fa 0%, #e8edf2 100%);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--text-muted);
  box-shadow: var(--shadow);
}

.site-footer a {
  font-weight: 500;
}

/* Print */
@media print {
  .icra-topbar,
  .conf-ribbon {
    -webkit-print-color-adjust: exact;
    print-color-adjust: exact;
  }

  body {
    background: #fff;
  }

  section,
  .hero-card,
  nav.toc {
    box-shadow: none;
  }

  .btn,
  .video-frame {
    break-inside: avoid;
  }
}