/* =============================================================================
   CIKM Tutorial site — base stylesheet
   Palette / structure modeled after the al-folio-style "hub" layout:
   light theme = purple accent, dark theme = cyan accent.
   Edit the CSS custom properties below to re-theme the whole site.
============================================================================= */

:root {
  color-scheme: light;
  --bg-color: #ffffff;
  --card-bg-color: #ffffff;
  --text-color: #1c1c1d;
  --text-color-light: #6c6c6c;
  --theme-color: #c7000b;
  --hover-color: #c7000b;
  --hover-text-color: #ffffff;
  --divider-color: rgba(0, 0, 0, 0.1);
  --footer-bg-color: #1c1c1d;
  --footer-text-color: #d6d6d6;
  --footer-link-color: #ffffff;
  --code-bg-color: rgba(199, 0, 11, 0.06);
  --shadow-color: rgba(0, 0, 0, 0.08);
  --navbar-bg-color: rgba(255, 255, 255, 0.92);
}

html[data-theme="dark"] {
  color-scheme: dark;
  --bg-color: #1c1c1d;
  --card-bg-color: #212529;
  --text-color: #e6e6e6;
  --text-color-light: #a3a3a3;
  --theme-color: #ff4d4d;
  --hover-color: #ff4d4d;
  --hover-text-color: #ffffff;
  --divider-color: #3a3a3d;
  --footer-bg-color: #101011;
  --footer-text-color: #b8b8b8;
  --footer-link-color: #ffffff;
  --code-bg-color: rgba(255, 77, 77, 0.12);
  --shadow-color: rgba(0, 0, 0, 0.4);
  --navbar-bg-color: rgba(28, 28, 29, 0.92);
}

@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]):not([data-theme="dark"]) {
    color-scheme: dark;
    --bg-color: #1c1c1d;
    --card-bg-color: #212529;
    --text-color: #e6e6e6;
    --text-color-light: #a3a3a3;
    --theme-color: #ff4d4d;
    --hover-color: #ff4d4d;
    --hover-text-color: #ffffff;
    --divider-color: #3a3a3d;
    --footer-bg-color: #101011;
    --footer-text-color: #b8b8b8;
    --footer-link-color: #ffffff;
    --code-bg-color: rgba(255, 77, 77, 0.12);
    --shadow-color: rgba(0, 0, 0, 0.4);
    --navbar-bg-color: rgba(28, 28, 29, 0.92);
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Roboto", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  background: var(--bg-color);
  color: var(--text-color);
  line-height: 1.65;
  transition: background 0.2s ease, color 0.2s ease;
}

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

a:hover {
  text-decoration: underline;
}

code {
  background: var(--code-bg-color);
  padding: 0.1em 0.4em;
  border-radius: 4px;
  font-size: 0.9em;
}

hr {
  border: none;
  border-top: 1px solid var(--divider-color);
  margin: 2.25rem 0;
}

.container {
  max-width: 980px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ---------------------------------------------------------------------------
   Navbar
--------------------------------------------------------------------------- */

.navbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--navbar-bg-color);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--divider-color);
}

.navbar-inner {
  max-width: 980px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.navbar-brand {
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--text-color);
  letter-spacing: 0.01em;
}

.navbar-brand:hover {
  text-decoration: none;
  color: var(--theme-color);
}

.navbar-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--text-color);
}

.navbar-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.navbar-links a {
  color: var(--text-color);
  font-size: 0.92rem;
  font-weight: 500;
  padding: 0.35rem 0;
  border-bottom: 2px solid transparent;
}

.navbar-links a:hover {
  color: var(--theme-color);
  text-decoration: none;
}

.navbar-links a.active {
  color: var(--theme-color);
  border-bottom-color: var(--theme-color);
}

.theme-toggle {
  background: none;
  border: 1px solid var(--divider-color);
  border-radius: 999px;
  cursor: pointer;
  color: var(--text-color);
  width: 34px;
  height: 34px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  line-height: 1;
}

.theme-toggle:hover {
  border-color: var(--theme-color);
  color: var(--theme-color);
}

@media (max-width: 720px) {
  .navbar-toggle {
    display: inline-flex;
  }

  .navbar-links {
    position: absolute;
    top: 56px;
    left: 0;
    right: 0;
    background: var(--bg-color);
    border-bottom: 1px solid var(--divider-color);
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    padding: 0.5rem 1.5rem 1rem;
    display: none;
  }

  .navbar-links.open {
    display: flex;
  }

  .navbar-links a {
    width: 100%;
    padding: 0.6rem 0;
    border-bottom: 1px solid var(--divider-color);
  }

  .navbar-links a.active {
    border-bottom: 1px solid var(--divider-color);
  }

  .navbar-links .theme-toggle {
    margin: 0.6rem 0 0.2rem;
  }
}

/* ---------------------------------------------------------------------------
   Page header / hero
--------------------------------------------------------------------------- */

.page-main {
  padding: 2.5rem 0 4rem;
}

.page-title {
  font-size: 2rem;
  font-weight: 700;
  margin: 0 0 0.25rem;
  letter-spacing: -0.01em;
}

.page-kicker {
  color: var(--theme-color);
  font-weight: 600;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin: 0 0 0.5rem;
}

.page-citation {
  border-left: 3px solid var(--theme-color);
  padding: 0.6rem 1rem;
  margin: 1rem 0 1.5rem;
  color: var(--text-color-light);
  font-size: 0.92rem;
  background: var(--code-bg-color);
  border-radius: 0 6px 6px 0;
}

.edition-banner {
  background: var(--code-bg-color);
  border: 1px solid var(--divider-color);
  border-radius: 8px;
  padding: 0.75rem 1rem;
  font-size: 0.92rem;
  margin-bottom: 1.75rem;
}

h2 {
  font-size: 1.4rem;
  font-weight: 700;
  margin: 2.25rem 0 1rem;
}

h3 {
  font-size: 1.12rem;
  font-weight: 700;
  margin: 1.5rem 0 0.5rem;
}

/* ---------------------------------------------------------------------------
   Cards (Explore grid + generic cards)
--------------------------------------------------------------------------- */

.card-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin: 1.25rem 0;
}

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

.card {
  display: block;
  background: var(--card-bg-color);
  border: 1px solid var(--divider-color);
  border-radius: 10px;
  padding: 1.25rem 1.4rem;
  color: inherit;
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}

a.card:hover {
  text-decoration: none;
  transform: translateY(-3px);
  box-shadow: 0 10px 24px var(--shadow-color);
  border-color: var(--theme-color);
}

.card-title {
  font-size: 1.05rem;
  font-weight: 700;
  margin: 0 0 0.35rem;
}

.card-text {
  margin: 0;
  color: var(--text-color-light);
  font-size: 0.92rem;
}

/* ---------------------------------------------------------------------------
   People / presenter cards (with photos)
--------------------------------------------------------------------------- */

.people-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin: 1.25rem 0;
}

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

.people-grid.single-col {
  grid-template-columns: 1fr;
}

.person-card {
  display: flex;
  align-items: center;
  gap: 1rem;
  background: var(--card-bg-color);
  border: 1px solid var(--divider-color);
  border-radius: 10px;
  padding: 0.9rem 1.1rem;
  color: inherit;
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}

a.person-card:hover {
  text-decoration: none;
  transform: translateY(-3px);
  box-shadow: 0 10px 24px var(--shadow-color);
  border-color: var(--theme-color);
}

.person-photo {
  width: 76px;
  height: 76px;
  min-width: 76px;
  border-radius: 50%;
  object-fit: cover;
  background: var(--code-bg-color);
  border: 1px solid var(--divider-color);
}

.person-name {
  font-size: 1rem;
  font-weight: 700;
  margin: 0 0 0.2rem;
  color: var(--text-color);
}

.person-affiliation {
  margin: 0 0 0.15rem;
  color: var(--text-color-light);
  font-size: 0.88rem;
}

.person-role {
  display: inline-block;
  margin-top: 0.25rem;
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--theme-color);
}

/* ---------------------------------------------------------------------------
   Editions list
--------------------------------------------------------------------------- */

.edition-item {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  border: 1px solid var(--divider-color);
  border-radius: 10px;
  padding: 1.1rem 1.3rem;
  margin-bottom: 0.9rem;
  background: var(--card-bg-color);
}

.edition-item.is-current {
  border-color: var(--theme-color);
}

.edition-item .edition-meta {
  color: var(--text-color-light);
  font-size: 0.88rem;
  margin: 0.2rem 0 0;
}

.edition-tag {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 0.2rem 0.55rem;
  border-radius: 999px;
  white-space: nowrap;
}

.edition-tag.current {
  background: var(--theme-color);
  color: var(--hover-text-color);
}

.edition-tag.future {
  background: var(--code-bg-color);
  color: var(--text-color-light);
  border: 1px dashed var(--divider-color);
}

.edition-placeholder {
  border: 1px dashed var(--divider-color);
  border-radius: 10px;
  padding: 1.1rem 1.3rem;
  color: var(--text-color-light);
  font-size: 0.92rem;
  font-style: italic;
}

/* ---------------------------------------------------------------------------
   Tables (outline, links)
--------------------------------------------------------------------------- */

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.92rem;
}

th,
td {
  text-align: left;
  padding: 0.55rem 0.7rem;
  border-bottom: 1px solid var(--divider-color);
}

th {
  color: var(--text-color-light);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* ---------------------------------------------------------------------------
   Session outline blocks
--------------------------------------------------------------------------- */

.session {
  border: 1px solid var(--divider-color);
  border-radius: 10px;
  padding: 1.1rem 1.3rem;
  margin: 1rem 0;
}

.session h3 {
  margin-top: 0;
}

.session-item {
  padding: 0.6rem 0;
  border-top: 1px solid var(--divider-color);
}

.session-item:first-of-type {
  border-top: none;
}

.session-item .item-title {
  font-weight: 600;
}

.session-item .item-time {
  color: var(--text-color-light);
  font-size: 0.85rem;
  font-weight: 400;
}

.session-item .item-desc {
  color: var(--text-color-light);
  font-size: 0.9rem;
  margin: 0.15rem 0 0;
}

/* ---------------------------------------------------------------------------
   Placeholder / TBD markers — visible reminders while customizing
--------------------------------------------------------------------------- */

.tbd {
  background: var(--code-bg-color);
  color: var(--theme-color);
  padding: 0.05em 0.45em;
  border-radius: 4px;
  font-size: 0.85em;
  font-weight: 600;
}

/* ---------------------------------------------------------------------------
   Buttons / links list
--------------------------------------------------------------------------- */

.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin: 1.25rem 0;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--divider-color);
  color: var(--text-color);
  font-size: 0.88rem;
  font-weight: 600;
}

.btn:hover {
  text-decoration: none;
  border-color: var(--theme-color);
  color: var(--theme-color);
}

.btn.primary {
  background: var(--theme-color);
  border-color: var(--theme-color);
  color: var(--hover-text-color);
}

.btn.primary:hover {
  opacity: 0.9;
  color: var(--hover-text-color);
}

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

.site-footer {
  background: var(--footer-bg-color);
  color: var(--footer-text-color);
  padding: 1.75rem 0;
  margin-top: 3rem;
  font-size: 0.85rem;
  text-align: center;
}

.site-footer a {
  color: var(--footer-link-color);
  font-weight: 600;
}

ul.plain {
  list-style: none;
  margin: 0;
  padding: 0;
}

ul.plain li {
  padding: 0.35rem 0;
}

.lede {
  font-size: 1.05rem;
  color: var(--text-color-light);
}