/* Minimal monochrome style, modeled on the VulGen'26 workshop site */

:root {
  --text: #111;
  --heading: #222;
  --meta: #666;
  --border: #d7dce3;
  --backdrop: #f5f6f8;
  --link: #222;
  --link-hover: #777;
  --todo-bg: #fff8e1;
  --todo-border: #e0b84c;
  --max-width: 1100px;
  --ff-body: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --ff-headings: Charter, "Bitstream Charter", "Sitka Text", Cambria, Georgia, serif;
}

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

html { scroll-behavior: smooth; scroll-padding-top: 5rem; }

body {
  margin: 0;
  background: #fff;
  color: var(--text);
  font-family: var(--ff-body);
  font-size: 17px;
  line-height: 1.65;
}

a { color: var(--link); text-underline-offset: 2px; }
a:hover { color: var(--link-hover); }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 16px;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: #fff;
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.25rem 1.5rem;
  padding-top: 0.75rem;
  padding-bottom: 0.75rem;
}
.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--ff-headings);
  font-weight: 700;
  font-size: 1.1rem;
  text-decoration: none;
}
.brand img { display: block; height: 35px; width: auto; }
.brand span { color: var(--meta); font-weight: 400; }
.main-nav {
  display: flex;
  gap: 1.25rem;
  overflow-x: auto;
  max-width: 100%;
  font-size: 0.95rem;
}
.main-nav a { text-decoration: none; white-space: nowrap; }
.main-nav a:hover { text-decoration: underline; }
.main-nav a[aria-current="page"] { font-weight: 700; text-decoration: underline; text-underline-offset: 6px; }

/* Content */
main section { padding: 1.5rem 0; }
main section + section { border-top: 1px solid var(--border); }

h1, h2, h3 { font-family: var(--ff-headings); color: var(--heading); line-height: 1.3; }
h1 { font-size: clamp(1.7rem, 4vw, 2.5rem); margin: 0 0 0.75rem; }
h2 { font-size: 1.6rem; margin: 0.5rem 0 1rem; }
h3 { font-size: 1.1rem; margin: 0 0 0.5rem; }

.hero { padding: 3rem 0 2rem; }
.hero .meta { color: var(--meta); font-size: 1.05rem; margin: 0; }

/* Home banner: Hong Kong photo with title and logos */
.hero-banner {
  position: relative;
  display: flex;
  align-items: center;
  min-height: 480px;
  padding: 4rem 0 3.5rem;
  background: #1b2333 url("img/hero-hong-kong.jpg") center 40% / cover no-repeat;
  color: #fff;
  text-align: center;
}
.hero-banner::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(rgba(10, 14, 24, 0.35), rgba(10, 14, 24, 0.6));
}
.hero-banner .container { position: relative; width: 100%; }
.hero-banner h1 {
  color: #fff;
  max-width: 900px;
  margin: 0 auto 1.5rem;
  text-shadow: 0 2px 12px rgba(0, 0, 0, 0.5);
}
.hero-logos {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 1rem 1.75rem;
  margin-bottom: 1.5rem;
}
.hero-logos img { display: block; height: 52px; width: auto; }
.hero-logos .wsdm-logo { border-radius: 6px; }
.hero-banner .meta { color: #e8eaee; font-size: 1.05rem; margin: 0; }
.hero-banner a { color: #fff; }
.hero-banner a:hover { color: #cfd3da; }
.photo-credit {
  position: absolute;
  right: 12px;
  bottom: 8px;
  margin: 0;
  font-size: 0.7rem;
  color: rgba(255, 255, 255, 0.7);
}
.photo-credit a { color: inherit; }

.note { color: var(--meta); margin-top: 0; }

/* Placeholders for text the organizers will write */
.todo {
  background: var(--todo-bg);
  border: 2px dashed var(--todo-border);
  border-radius: 6px;
  padding: 1rem 1.25rem;
  margin: 0 0 1rem;
  color: #6b5200;
}
.tba { color: var(--meta); font-style: italic; }
.tba-block { color: var(--meta); font-style: italic; font-size: 1.1rem; }

/* Topics */
.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1rem;
}
.topic {
  background: var(--backdrop);
  border-radius: 8px;
  padding: 1.1rem 1.25rem;
}
.topic ul { margin: 0; padding-left: 1.1rem; }
.topic li { margin: 0.2rem 0; }
.num {
  display: inline-block;
  width: 1.6em;
  height: 1.6em;
  line-height: 1.6em;
  text-align: center;
  border-radius: 50%;
  background: var(--heading);
  color: #fff;
  font-family: var(--ff-body);
  font-size: 0.85em;
  margin-right: 0.35rem;
}

/* CFP */
.facts { padding-left: 1.1rem; }
.facts li { margin: 0.35rem 0; }
.button {
  display: inline-block;
  padding: 0.6rem 1.2rem;
  border-radius: 6px;
  background: var(--heading);
  color: #fff;
  text-decoration: none;
}
.button:hover { background: var(--link-hover); color: #fff; }
.button.disabled { background: #bbb; cursor: not-allowed; }

/* Dates */
.dates { border-collapse: collapse; width: 100%; max-width: 560px; }
.dates th, .dates td { text-align: left; padding: 0.6rem 0.5rem; border-bottom: 1px solid var(--border); }
.dates th { font-weight: 600; }
.dates td { white-space: nowrap; }

/* Sub-pages */
.page-title { margin: 2.5rem 0 0.5rem; }

/* Schedule */
.schedule { border-collapse: collapse; width: 100%; max-width: 640px; }
.schedule td { padding: 0.55rem 0.5rem; border-bottom: 1px solid var(--border); vertical-align: top; }
.schedule td:first-child { white-space: nowrap; font-variant-numeric: tabular-nums; width: 8.5rem; color: var(--meta); }
.schedule .part th { text-align: left; font-family: var(--ff-headings); font-size: 1.1rem; padding: 1.25rem 0.5rem 0.4rem; }
.schedule .break td { color: var(--meta); font-style: italic; }

/* Keynotes */
.keynote { display: flex; gap: 1.5rem; align-items: flex-start; padding: 1.5rem 0; }
.keynote + .keynote { border-top: 1px solid var(--border); }
.keynote .avatar { flex: none; margin: 0; width: 140px; height: 140px; }
.keynote-body h2 { margin: 0; }
.keynote-body h2 a { text-decoration: none; }
.keynote-body h2 a:hover { text-decoration: underline; }
.keynote-body .aff { margin: 0.1rem 0 0.75rem; font-size: 1rem; }
@media (max-width: 600px) {
  .keynote { flex-direction: column; align-items: center; }
}

/* Organizers */
.people {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(170px, 1fr));
  gap: 1.5rem 1rem;
  text-align: center;
}
.avatar {
  width: 110px;
  height: 110px;
  margin: 0 auto 0.6rem;
  border-radius: 50%;
  background: var(--backdrop);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--ff-headings);
  font-size: 1.8rem;
  color: var(--meta);
  overflow: hidden;
}
.avatar img { width: 100%; height: 100%; object-fit: cover; }
.name { font-weight: 600; }
.name a { text-decoration: none; }
.name a:hover { text-decoration: underline; }
.aff { color: var(--meta); font-size: 0.9rem; line-height: 1.4; }

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  margin-top: 2rem;
  padding: 1.5rem 0;
  color: var(--meta);
  font-size: 0.95rem;
}
.site-footer p { margin: 0.25rem 0; }

@media (max-width: 600px) {
  body { font-size: 16px; }
  .hero { padding: 2rem 0 1.25rem; }
  .hero-banner { min-height: 0; padding: 3rem 0 2.75rem; }
  .hero-logos img { height: 40px; }
  .dates td { white-space: normal; }
}