/* =========================================================
   ISBI 2026 – POCUS-AI Workshop
   ========================================================= */

/* ---------- CSS VARIABLES ---------- */
:root {
    --primary: #002a5c;        /* ISBI / IEEE navy */
    --accent: #00b1e6;         /* ISBI cyan */
    --bg: #f8fafc;
    --bg-alt: #e6f4f7;
    --text: #1a1a1a;
    --muted: #5f6b7a;
    --card-bg: #ffffff;
    --border: #e5e7eb;
  }
  
  /* Dark mode */
  [data-theme="dark"] {
    --bg: #020617;
    --bg-alt: #020617;
    --text: #e5e7eb;
    --muted: #9ca3af;
    --card-bg: #020617;
    --border: #1f2937;
  }
  
  /* ---------- RESET ---------- */
  *,
  *::before,
  *::after {
    box-sizing: border-box;
  }
  
  html {
    scroll-behavior: smooth;
  }
  
  body {
    margin: 0;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
      Roboto, Inter, sans-serif;
    line-height: 1.6;
    background: var(--bg);
    color: var(--text);
  }
  
  /* ---------- ACCESSIBILITY ---------- */
  :focus-visible {
    outline: 3px solid var(--accent);
    outline-offset: 3px;
  }
  
  .skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--accent);
    color: #000;
    padding: 0.5rem;
    z-index: 100;
  }
  .skip-link:focus {
    top: 0;
  }
  
  /* ---------- LAYOUT ---------- */
  .container {
    max-width: 1100px;
    margin: auto;
    padding: 2rem 1.25rem;
  }
  
  .section {
    margin: 3.5rem 0;
  }
  
  .grid {
    display: grid;
    gap: 1.75rem;
  }
  
  @media (min-width: 768px) {
    .grid {
      grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    }
  }
  
  /* ---------- NAVBAR ---------- */
  .navbar {
    background: var(--card-bg);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 50;
  }
  
  .nav-flex {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }
  
  .logo {
    font-weight: 700;
    font-size: 1rem;
  }
  
  .nav-links {
    display: flex;
    gap: 1.25rem;
  }
  
  .nav-links a {
    text-decoration: none;
    color: var(--text);
    font-weight: 500;
  }
  
  .nav-links a:hover {
    color: var(--accent);
  }
  
  /* Mobile nav */
  .menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.25rem;
  }
  
  @media (max-width: 768px) {
    .menu-toggle {
      display: block;
    }
  
    .nav-links {
      display: none;
      flex-direction: column;
      background: var(--card-bg);
      position: absolute;
      top: 60px;
      right: 1rem;
      padding: 1rem;
      border-radius: 8px;
      border: 1px solid var(--border);
    }
  
    .nav-links.open {
      display: flex;
    }
  }
  
  /* ---------- HERO ---------- */
  .hero {
    background: linear-gradient(135deg, var(--primary), #001b3f);
    color: white;
    text-align: center;
    padding: 4rem 1.5rem;
  }
  
  .hero h1 {
    font-size: 2.6rem;
    margin-bottom: 0.5rem;
  }
  
  .subtitle {
    font-size: 1.1rem;
    opacity: 0.9;
  }
  
  /* ---------- CARDS ---------- */
  .card,
  .speaker-card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 1.5rem;
    border: 1px solid var(--border);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }
  
  .card:hover,
  .speaker-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 16px 30px rgba(0, 0, 0, 0.12);
  }
  
  .highlight {
    background: var(--bg-alt);
  }
  
  /* ---------- SPEAKER CARDS ---------- */
  .speaker-card {
    padding: 0;
    overflow: hidden;
  }
  
  .speaker-card img {
    width: 100%;
    height: 220px;
    /* object-fit: cover; */
    object-fit: contain;
  }
  
  .card-body {
    padding: 1rem 1.25rem;
  }
  
  /* ---------- ORGANIZERS CARDS ---------- */
  .org-card {
    padding: 0;
    overflow: hidden;
  }
  
  .org-card img {
    width: 100%;
    height: 220px;
    /* object-fit: cover; */
    object-fit: contain;
  }
  
  .card-body {
    padding: 1rem 1.25rem;
  }
  /* ---------- TABLES ---------- */
  table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
  }
  
  th,
  td {
    padding: 0.75rem;
    border-bottom: 1px solid var(--border);
    text-align: left;
  }
  
  th {
    background: var(--bg-alt);
  }
  
  /* ---------- LINKS & BUTTONS ---------- */
  a {
    color: var(--primary);
  }
  
  a:hover {
    color: var(--accent);
  }
  
  .button {
    display: inline-block;
    padding: 0.65rem 1.2rem;
    border-radius: 8px;
    font-weight: 600;
    text-decoration: none;
    margin-top: 1rem;
  }
  
  .button.primary {
    background: var(--accent);
    color: #002a5c;
  }
  
  .button.secondary {
    background: var(--primary);
    color: white;
  }
  
  /* ---------- ANIMATIONS ---------- */
  .animate {
    opacity: 0;
    transform: translateY(20px);
  }
  
  .fade-in {
    opacity: 1;
    transform: translateY(0);
    transition: opacity 0.6s ease, transform 0.6s ease;
  }
  
  /* Reduced motion */
  @media (prefers-reduced-motion: reduce) {
    .animate,
    .fade-in {
      transition: none;
      transform: none;
      opacity: 1;
    }
  }
  
  /* ---------- FOOTER ---------- */
  .site-footer {
    background: #020617;
    color: #9ca3af;
    text-align: center;
    padding: 1.5rem;
    font-size: 0.9rem;
  }
  
  /* ---------- PRINT ---------- */
  @media print {
    nav,
    footer,
    .no-print,
    .menu-toggle {
      display: none !important;
    }
  
    body {
      background: white;
      color: black;
    }
  
    table {
      font-size: 12pt;
    }
  }

  .openreview-badge {
    display: inline-block;
    padding: 0.6rem 1rem;
    border-radius: 999px;
    background: #f97316;
    color: white;
    font-weight: 700;
    text-decoration: none;
    margin-top: 1rem;
  }
  
  .openreview-badge:hover {
    background: #ea580c;
  }

  .sponsors {
    align-items: center;
    text-align: center;
  }
  
  .sponsors img {
    max-height: 60px;
    margin: auto;
    filter: grayscale(100%);
    opacity: 0.85;
    transition: opacity 0.3s ease, filter 0.3s ease;
  }
  
  .sponsors img:hover {
    filter: none;
    opacity: 1;
  }
  
  /* ---------- Back to top ---------- */
.back-to-top {
    position: fixed;
    bottom: 1.25rem;
    right: 1.25rem;
    background: var(--accent);
    color: #002a5c;
    padding: 0.5rem 0.75rem;
    border-radius: 999px;
    font-weight: 600;
    text-decoration: none;
    font-size: 0.9rem;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
    z-index: 100;
  }
  
  .back-to-top.visible {
    opacity: 1;
    pointer-events: auto;
  }
  
  .back-to-top:focus-visible {
    outline: 3px solid #fff;
    outline-offset: 3px;
  }
  
  /* ---------- Dark mode link colors ---------- */
[data-theme="dark"] a {
    color: #7dd3fc; /* accessible light cyan */
  }
  
  [data-theme="dark"] a:hover {
    color: #38bdf8;
  }
  
  [data-theme="dark"] .navbar a {
    color: #e5e7eb;
  }
  
  [data-theme="dark"] .navbar a:hover {
    color: var(--accent);
  }

  #darkToggle {
    background: none;
    border: none;
    font-size: 1.2rem;
    cursor: pointer;
    color: var(--text);
  }
  
  [data-theme="dark"] #darkToggle {
    color: #e5e7eb;
  }