/* ==========================================================================
   LLM4XAI Workshop — shared stylesheet
   Palette inspired by the Hugo Blox "emerald" theme
   ========================================================================== */

:root {
  --primary-100: #064e3b;
  --primary-400: #34d399;
  --primary-500: #10b981;
  --primary-600: #059669;
  --primary-700: #047857;

  --bg:        #0a0f1f;
  --bg-alt:    #0d1526;
  --bg-card:   #111c33;
  --text:      #e8ecf4;
  --text-muted:#8fa0bf;
  --border:    #22304d;

  --radius: 0.75rem;
  --shadow: 0 1px 0 rgba(255,255,255,0.04) inset, 0 4px 16px rgba(0,0,0,0.45);
  --shadow-hover: 0 1px 0 rgba(255,255,255,0.06) inset, 0 10px 28px rgba(0,0,0,0.55), 0 0 0 1px rgba(16,185,129,0.25);
  --max-width: 1120px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--primary-400); text-decoration: none; }
a:hover { color: var(--primary-500); }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

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

/* -------------------- Header / Nav -------------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(10,15,31,0.85);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--border);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
  max-width: var(--max-width);
  margin: 0 auto;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--text);
}

.brand .accent { color: var(--primary-600); }

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--text-muted);
  font-weight: 500;
  font-size: 0.95rem;
  padding-bottom: 0.25rem;
  border-bottom: 2px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}

.nav-links a:hover,
.nav-links a[aria-current="page"] {
  color: var(--text);
  border-bottom-color: var(--primary-600);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  margin: 4px 0;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

@media (max-width: 720px) {
  .nav-toggle { display: block; }

  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    gap: 0;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.25s ease;
  }

  .nav-links.open { max-height: 320px; }

  .nav-links li { width: 100%; }

  .nav-links a {
    display: block;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--border);
    border-left: 2px solid transparent;
  }

  .nav-links a[aria-current="page"] {
    border-bottom: 1px solid var(--border);
    border-left-color: var(--primary-600);
  }
}

/* -------------------- Hero -------------------- */

.hero {
  background: linear-gradient(180deg, var(--bg-alt) 0%, var(--bg) 100%);
  border-bottom: 1px solid var(--border);
  padding: 5rem 0 4rem;
  text-align: center;
}

.eyebrow {
  display: inline-block;
  background: var(--primary-100);
  color: var(--primary-400);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  padding: 0.35rem 0.9rem;
  border-radius: 999px;
  margin-bottom: 1.5rem;
}

.hero h1 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin: 0 0 0.75rem;
}

.hero .subtitle {
  font-size: 1.15rem;
  color: var(--text-muted);
  max-width: 640px;
  margin: 0 auto 1.75rem;
}

.hero .meta {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 2rem;
}

.hero .meta strong { color: var(--text); }

.cta-row {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* -------------------- Buttons -------------------- */

.btn {
  display: inline-block;
  font-weight: 600;
  font-size: 0.95rem;
  padding: 0.7rem 1.5rem;
  border-radius: 0.5rem;
  transition: transform 0.1s ease, box-shadow 0.15s ease, background 0.15s ease;
  border: 1px solid transparent;
}

.btn-primary {
  background: var(--primary-600);
  color: #fff;
}

.btn-primary:hover {
  background: var(--primary-700);
  color: #fff;
  box-shadow: var(--shadow-hover);
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text);
  border-color: var(--border);
}

.btn-secondary:hover {
  border-color: var(--primary-500);
  color: var(--primary-400);
}

/* -------------------- Sections -------------------- */

section { padding: 4rem 0; }

section.alt { background: var(--bg-alt); }

.section-heading {
  text-align: center;
  margin-bottom: 2.5rem;
}

.section-heading h2 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin: 0 0 0.5rem;
}

.section-heading p {
  color: var(--text-muted);
  max-width: 620px;
  margin: 0 auto;
}

/* -------------------- Cards -------------------- */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.25rem;
}

.stack {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow);
  transition: box-shadow 0.15s ease, transform 0.15s ease;
}

.card:hover {
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
}

.card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.05rem;
}

.card p { margin: 0; color: var(--text-muted); font-size: 0.95rem; }

/* Dates strip */

.dates-strip {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin-top: 1rem;
}

.date-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-left: 3px solid var(--primary-600);
  border-radius: var(--radius);
  padding: 1.1rem 1.25rem;
  box-shadow: var(--shadow);
}

.date-card .label {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-muted);
  font-weight: 600;
}

.date-card .value {
  font-size: 1.05rem;
  font-weight: 700;
  margin-top: 0.25rem;
}

.date-card .value.tbd { color: var(--text-muted); font-weight: 600; }

/* -------------------- Tables -------------------- */

.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

table {
  width: 100%;
  border-collapse: collapse;
  min-width: 560px;
  background: var(--bg-card);
}

thead th {
  background: var(--bg-alt);
  text-align: left;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  color: var(--text-muted);
  padding: 0.9rem 1.1rem;
  border-bottom: 1px solid var(--border);
}

tbody td {
  padding: 0.9rem 1.1rem;
  border-bottom: 1px solid var(--border);
  font-size: 0.95rem;
  vertical-align: top;
}

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

tbody tr:hover { background: var(--bg-alt); }

.time-cell { white-space: nowrap; font-weight: 600; color: var(--primary-400); width: 140px; }

/* -------------------- Lists -------------------- */

.topic-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 0.6rem 1.5rem;
}

.topic-list li {
  font-size: 0.95rem;
  color: var(--text);
  display: flex;
  gap: 0.65rem;
  align-items: flex-start;
}

.topic-list li::before {
  content: "";
  flex: none;
  width: 8px;
  height: 8px;
  margin-top: 0.5rem;
  border-radius: 50%;
  background: var(--primary-500);
}

/* -------------------- Notice / TBD banner -------------------- */

.notice {
  background: var(--primary-100);
  border: 1px solid var(--primary-700);
  color: var(--primary-400);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  font-size: 0.92rem;
  margin-bottom: 2rem;
}

/* -------------------- Organizers -------------------- */

.people-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.25rem;
}

.person {
  text-align: center;
}

.avatar {
  width: 76px;
  height: 76px;
  border-radius: 50%;
  background: var(--primary-100);
  color: var(--primary-400);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.2rem;
  margin: 0 auto 0.75rem;
}

.person .name { font-weight: 600; font-size: 0.98rem; }
.person .role { color: var(--text-muted); font-size: 0.85rem; margin-top: 0.15rem; }
.person .bio { color: var(--text-muted); font-size: 0.82rem; margin-top: 0.5rem; line-height: 1.5; }

.tag {
  display: inline-block;
  background: var(--primary-100);
  color: var(--primary-400);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  padding: 0.15rem 0.55rem;
  border-radius: 999px;
  margin-top: 0.4rem;
}

/* -------------------- Footer -------------------- */

.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg-alt);
  padding: 2.5rem 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.site-footer a { color: var(--text-muted); }
.site-footer a:hover { color: var(--primary-400); }

.footer-links {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
}

/* -------------------- Utilities -------------------- */

.text-center { text-align: center; }
.mt-lg { margin-top: 2.5rem; }