/* ==========================================================
   IDCNE 2026 Conference Website - Optimized IEEE-style layout
   Content is kept unchanged; this stylesheet improves visual
   hierarchy, spacing, navigation, cards, tables, gallery, and
   responsive behavior for conference-paper submission websites.
   ========================================================== */

/* ---------- Theme Variables ---------- */
:root {
  --color-primary: #00629b;
  --color-primary-dark: #003b5c;
  --color-primary-soft: #eaf5fb;
  --color-navy: #071d33;
  --color-navy-2: #0b2d4a;
  --color-gold: #f0b429;
  --color-bg: #f4f7fb;
  --color-bg-2: #eef4f9;
  --color-card: #ffffff;
  --color-text: #1f2937;
  --color-muted: #5f6b7a;
  --color-line: #d8dee8;
  --color-line-strong: #bdcad9;

  --radius-card: 18px;
  --radius-small: 12px;
  --site-width: 1180px;
  --shadow-card: 0 14px 36px rgba(15, 23, 42, 0.08);
  --shadow-soft: 0 8px 24px rgba(15, 23, 42, 0.06);
}

/* ---------- Base Styles ---------- */
* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(circle at top left, rgba(0, 98, 155, 0.10), transparent 32rem),
    linear-gradient(180deg, #ffffff 0, var(--color-bg) 36rem);
  color: var(--color-text);
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.7;
  text-rendering: optimizeLegibility;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color 0.2s ease, background 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
}

a:focus-visible,
summary:focus-visible,
.button:focus-visible {
  outline: 3px solid rgba(240, 180, 41, 0.75);
  outline-offset: 3px;
}

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

.container,
.inner {
  width: min(var(--site-width), calc(100% - 40px));
  margin: 0 auto;
}

p { margin: 0 0 14px; }

/* ==========================================================
   Header / Navigation
   ========================================================== */
.topbar {
  background: linear-gradient(90deg, var(--color-primary-dark), var(--color-navy));
  color: #dbeafe;
  font-size: 13px;
  letter-spacing: 0.01em;
}

.topbar .inner {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 9px 0;
  flex-wrap: wrap;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.96);
  border-bottom: 1px solid rgba(216, 222, 232, 0.9);
  box-shadow: 0 12px 28px rgba(15, 23, 42, 0.06);
  backdrop-filter: blur(14px);
}

.site-header .inner {
  min-height: 78px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 13px;
  min-width: max-content;
}

.brand:hover { transform: translateY(-1px); }

.brand-mark {
  width: 50px;
  height: 50px;
  border-radius: 14px;
  background:
    linear-gradient(135deg, rgba(255,255,255,0.18), transparent 45%),
    linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  color: #ffffff;
  display: grid;
  place-items: center;
  font-weight: 900;
  letter-spacing: -0.04em;
  box-shadow: 0 10px 22px rgba(0, 59, 92, 0.22);
}

.brand-title {
  display: block;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 24px;
  font-weight: 800;
  color: var(--color-primary-dark);
  line-height: 1.05;
}

.brand-subtitle {
  display: block;
  font-size: 12px;
  color: var(--color-muted);
  margin-top: 3px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.main-nav {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 5px;
  flex-wrap: wrap;
}

.main-nav a,
.dropdown-title {
  padding: 9px 12px;
  border-radius: 999px;
  color: #263445;
  font-size: 14px;
  font-weight: 800;
}

.main-nav a:hover,
.main-nav a.active,
.nav-dropdown:hover .dropdown-title,
.nav-dropdown[open] .dropdown-title,
.nav-dropdown.active .dropdown-title {
  color: var(--color-primary);
  background: var(--color-primary-soft);
}

.nav-dropdown {
  position: relative;
  display: inline-flex;
  align-items: center;
}

.dropdown-title {
  list-style: none;
  cursor: pointer;
  user-select: none;
  padding-right: 28px;
  position: relative;
}

.dropdown-title::-webkit-details-marker { display: none; }

.dropdown-title::after {
  content: "▾";
  position: absolute;
  right: 11px;
  top: 50%;
  transform: translateY(-48%);
  font-size: 12px;
}

.dropdown-panel {
  position: absolute;
  top: 44px;
  left: 0;
  min-width: 165px;
  background: #ffffff;
  border: 1px solid var(--color-line);
  border-radius: 14px;
  box-shadow: 0 18px 42px rgba(15, 23, 42, 0.16);
  padding: 8px;
  z-index: 200;
}

.dropdown-panel a {
  display: block;
  border-radius: 10px;
  white-space: nowrap;
  padding: 9px 12px;
}

/* ==========================================================
   Hero / Page Header
   ========================================================== */
h1,
h2,
h3,
h4 {
  font-family: Georgia, "Times New Roman", serif;
  line-height: 1.16;
  margin: 0;
  color: var(--color-navy);
}

.home-hero {
  min-height: 650px;
  color: #ffffff;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
  background:
    linear-gradient(105deg, rgba(7, 29, 51, 0.96), rgba(0, 98, 155, 0.82) 52%, rgba(7, 29, 51, 0.34)),
    url("images/首页/u0.jpg") center / cover no-repeat;
}

.home-hero::after,
.page-header::after {
  content: "";
  position: absolute;
  inset: auto -10% -28% -10%;
  height: 46%;
  background: radial-gradient(ellipse at center, rgba(240, 180, 41, 0.20), transparent 58%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  width: min(var(--site-width), calc(100% - 40px));
  margin: 0 auto;
  padding: 104px 0;
}

.hero-label {
  display: inline-flex;
  color: #fef3c7;
  background: rgba(255, 255, 255, 0.13);
  border: 1px solid rgba(255, 255, 255, 0.28);
  border-radius: 999px;
  padding: 8px 15px;
  font-size: 14px;
  font-weight: 900;
  margin-bottom: 22px;
  box-shadow: 0 10px 26px rgba(0,0,0,0.12);
}

.home-hero h1 {
  color: #ffffff;
  max-width: 1010px;
  font-size: clamp(38px, 5vw, 68px);
  letter-spacing: -1.4px;
}

.hero-description {
  max-width: 835px;
  margin: 24px 0 0;
  font-size: clamp(18px, 2vw, 23px);
  color: #e7f4fb;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin: 34px 0 24px;
}

.meta-card {
  min-width: 220px;
  padding: 16px 18px;
  border-radius: var(--radius-card);
  background: rgba(255, 255, 255, 0.14);
  border: 1px solid rgba(255, 255, 255, 0.28);
  box-shadow: 0 12px 28px rgba(0,0,0,0.10);
}

.meta-card strong {
  display: block;
  font-size: 12px;
  color: #bfdbfe;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.meta-card span {
  font-size: 16px;
  font-weight: 900;
  color: #ffffff;
}

.page-header {
  position: relative;
  overflow: hidden;
  background:
    linear-gradient(105deg, rgba(7, 29, 51, 0.97), rgba(0, 98, 155, 0.91)),
    url("images/首页/u0.jpg") center / cover no-repeat;
  color: #ffffff;
  padding: 82px 0 76px;
}

.page-header .container { position: relative; z-index: 1; }

.page-header h1 {
  color: #ffffff;
  font-size: clamp(34px, 5vw, 56px);
  letter-spacing: -0.7px;
}

.page-header p {
  max-width: 850px;
  margin: 18px 0 0;
  color: #e6f3fb;
  font-size: 18px;
}

.breadcrumb {
  display: inline-flex;
  gap: 5px;
  color: #bfdbfe;
  font-size: 14px;
  font-weight: 900;
  margin-bottom: 14px;
  padding: 6px 12px;
  border-radius: 999px;
  background: rgba(255,255,255,0.10);
  border: 1px solid rgba(255,255,255,0.18);
}

/* ==========================================================
   Buttons
   ========================================================== */
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 24px;
  border-radius: 999px;
  font-weight: 900;
  margin: 8px 10px 6px 0;
  box-shadow: 0 12px 28px rgba(0,0,0,0.10);
}

.button:hover { transform: translateY(-2px); }

.button-primary {
  background: var(--color-gold);
  color: #172033;
}

.button-secondary {
  color: #ffffff;
  border: 1px solid rgba(255, 255, 255, 0.52);
  background: rgba(255, 255, 255, 0.09);
}

/* ==========================================================
   Page Layout
   ========================================================== */
.page-main { padding: 62px 0 82px; }

.section-title {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 30px;
  border-bottom: 1px solid var(--color-line);
  padding-bottom: 18px;
}

.section-title h2 { font-size: clamp(28px, 4vw, 42px); }

.section-title p {
  max-width: 650px;
  margin: 0;
  color: var(--color-muted);
}

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: 24px;
}

.span-4 { grid-column: span 4; }
.span-6 { grid-column: span 6; }
.span-8 { grid-column: span 8; }
.span-12 { grid-column: span 12; }

/* ==========================================================
   Content Components
   ========================================================== */
.card {
  background: rgba(255,255,255,0.96);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-card);
  padding: 30px;
  box-shadow: var(--shadow-card);
}

.card:hover { box-shadow: 0 18px 44px rgba(15, 23, 42, 0.10); }

.card h2,
.card h3 { margin-bottom: 14px; }

.card h2 { font-size: clamp(26px, 3vw, 36px); }
.card h3 { font-size: clamp(22px, 2.3vw, 28px); }

.card > h2::after,
.card > h3::after,
.section-title h2::after {
  content: "";
  display: block;
  width: 56px;
  height: 4px;
  border-radius: 999px;
  margin-top: 12px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-gold));
}

.check-list,
.bullet-list {
  display: grid;
  gap: 11px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.check-list li,
.bullet-list li {
  position: relative;
  padding: 13px 15px 13px 43px;
  background: linear-gradient(180deg, #ffffff, #f8fafc);
  border: 1px solid var(--color-line);
  border-radius: 13px;
}

.check-list li::before {
  content: "✓";
  position: absolute;
  left: 15px;
  top: 12px;
  color: var(--color-primary);
  font-weight: 900;
}

.bullet-list li::before {
  content: "•";
  position: absolute;
  left: 18px;
  top: 9px;
  color: var(--color-primary);
  font-weight: 900;
  font-size: 22px;
}

.two-column-list {
  columns: 2;
  column-gap: 38px;
  padding-left: 22px;
  margin: 14px 0 0;
}

.two-column-list li {
  break-inside: avoid;
  margin: 0 0 10px;
  padding-left: 2px;
}

table {
  width: 100%;
  border-collapse: collapse;
  background: #ffffff;
  border-radius: var(--radius-card);
  overflow: hidden;
  box-shadow: var(--shadow-soft);
  margin: 14px 0;
  border: 1px solid var(--color-line);
}

th,
td {
  padding: 16px 18px;
  border-bottom: 1px solid var(--color-line);
  text-align: left;
  vertical-align: top;
}

tr:last-child td { border-bottom: 0; }

th {
  background: linear-gradient(90deg, var(--color-primary-dark), var(--color-primary));
  color: #ffffff;
  text-transform: uppercase;
  font-size: 14px;
  letter-spacing: 0.04em;
}

tbody tr:nth-child(even) td { background: #f8fafc; }

.strong-cell {
  font-weight: 900;
  color: var(--color-primary-dark);
}

.notice {
  border-left: 5px solid var(--color-primary);
  background: #f8fafc;
  border-radius: 0 14px 14px 0;
  padding: 17px 19px;
  margin: 18px 0 0;
}

.gallery {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
  margin-top: 24px;
}

.gallery figure {
  margin: 0;
  overflow: hidden;
  border-radius: var(--radius-card);
  background: #ffffff;
  border: 1px solid var(--color-line);
  box-shadow: var(--shadow-soft);
}

.gallery img {
  width: 100%;
  height: 210px;
  object-fit: cover;
  background: linear-gradient(135deg, #eaf0f6, #f8fafc);
}

.gallery figcaption {
  padding: 13px 15px;
  font-size: 14px;
  color: var(--color-muted);
}

/* Speakers page: keep photo and biography in one profile block.
   The speaker portrait is intentionally compact so the biography remains dominant. */
.speaker-profile {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 30px;
  align-items: center;
}

.speaker-photo {
  width: 240px;
  max-width: 100%;
  margin: 0;
  padding: 12px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-card);
  background: #f8fafc;
  box-shadow: var(--shadow-soft);
}

.speaker-photo img {
  width: auto;
  max-width: 210px;
  max-height: 260px;
  height: auto;
  object-fit: contain;
  border-radius: calc(var(--radius-card) - 6px);
  background: #ffffff;
  margin: 0 auto;
}

.speaker-bio h3 { margin-bottom: 16px; }
.speaker-bio p { margin-bottom: 0;  text-align: justify;}

/* ==========================================================
   Venue Page: image-text matched layout
   ========================================================== */
.venue-intro-card { padding: 34px; }
/* .venue-intro-card p { margin-bottom: 14px;} */

.venue-intro-card > p,
.venue-feature-content > p {
  text-align: justify;
  text-justify: inter-word;
}

.venue-feature-list {
  display: grid;
  gap: 28px;
}

.venue-feature {
  display: grid;
  grid-template-columns: minmax(280px, 42%) 1fr;
  gap: 0;
  align-items: stretch;
  background: var(--color-card);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-card);
  overflow: hidden;
  box-shadow: var(--shadow-card);
}

.venue-feature:nth-child(even) { grid-template-columns: 1fr minmax(280px, 42%); }
.venue-feature:nth-child(even) .venue-feature-media { order: 2; }

.venue-feature-media {
  min-height: 300px;
  background: #eaf0f6;
}

.venue-feature-media img {
  width: 100%;
  height: 100%;
  min-height: 300px;
  object-fit: cover;
}

.venue-feature-content {
  padding: 34px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.venue-feature-content h3 {
  color: var(--color-primary-dark);
  font-size: clamp(25px, 3vw, 32px);
  margin-bottom: 12px;
}

/* .venue-feature-content p { margin: 0; } */

.venue-feature-tag {
  display: inline-flex;
  width: fit-content;
  margin-bottom: 13px;
  padding: 6px 13px;
  border-radius: 999px;
  background: var(--color-primary-soft);
  color: var(--color-primary);
  font-size: 13px;
  font-weight: 900;
}

/* ==========================================================
   History pages
   ========================================================== */

.history-intro { position: relative; overflow: hidden; }

.history-intro p {
  text-align: justify;
  text-justify: inter-word;
}

.history-meta {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  margin-top: 24px;
}

.history-meta-item {
  padding: 16px;
  border: 1px solid var(--color-line);
  border-radius: 14px;
  background: #f8fafc;
}

.history-meta-item strong {
  display: block;
  color: var(--color-primary-dark);
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.history-meta-item span {
  display: block;
  margin-top: 5px;
  font-weight: 800;
}

.history-gallery-title {
  margin: 34px 0 18px;
  border-bottom: 1px solid var(--color-line);
  padding-bottom: 14px;
}

.history-gallery-title h2 { font-size: clamp(28px, 4vw, 40px); }

.history-photo-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

.history-photo-grid figure {
  width: fit-content;
  max-width: 100%;
  margin: 0 auto;
  background: #ffffff;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-card);
  overflow: hidden;
  box-shadow: var(--shadow-soft);
}

.history-photo-grid figure.featured { grid-column: auto; }

.history-photo-grid img {
  width: auto;
  height: auto;
  max-width: 100%;
  object-fit: contain;
  background: #eaf0f6;
  margin: 0 auto;
}

.history-photo-grid figure.featured img {
  width: auto;
  height: auto;
  max-width: 100%;
}

.history-photo-grid figcaption {
  padding: 15px 16px;
  color: var(--color-muted);
  font-size: 14px;
  max-width: 760px;
}

.history-photo-grid figcaption strong {
  display: block;
  color: var(--color-navy);
  font-size: 16px;
  margin-bottom: 4px;
}

/* ==========================================================
   Footer
   ========================================================== */
.site-footer {
  background:
    radial-gradient(circle at top right, rgba(0, 98, 155, 0.30), transparent 26rem),
    var(--color-navy);
  color: #dbeafe;
  padding: 46px 0 28px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.45fr 1fr 1fr;
  gap: 28px;
  margin-bottom: 28px;
}

.site-footer h3 {
  color: #ffffff;
  font-size: 21px;
  margin-bottom: 10px;
}

.site-footer p,
.site-footer a {
  color: #bdd7ea;
  margin: 0 0 8px;
}

.site-footer a:hover { color: #ffffff; }

.copyright {
  border-top: 1px solid rgba(255, 255, 255, 0.13);
  padding-top: 18px;
  color: #9fbad0;
  font-size: 13px;
}

/* ==========================================================
   Responsive Layout
   ========================================================== */
@media (max-width: 1040px) {
  .site-header .inner {
    align-items: flex-start;
    flex-direction: column;
    padding: 14px 0;
  }

  .main-nav { justify-content: flex-start; }
}

@media (max-width: 980px) {
  .span-4,
  .span-6,
  .span-8 { grid-column: span 12; }

  .footer-grid { grid-template-columns: 1fr; }
  .gallery { grid-template-columns: repeat(2, 1fr); }
  .two-column-list { columns: 1; }
  .speaker-profile { grid-template-columns: 1fr; }
  .speaker-photo { width: 260px; max-width: 100%; margin: 0 auto; }

  .venue-feature,
  .venue-feature:nth-child(even) { grid-template-columns: 1fr; }
  .venue-feature:nth-child(even) .venue-feature-media { order: 0; }
  .venue-feature-media,
  .venue-feature-media img { min-height: 250px; }

  .history-meta { grid-template-columns: repeat(2, 1fr); }
  .history-photo-grid { grid-template-columns: 1fr; }
  .history-photo-grid figure.featured { grid-column: auto; }
}

@media (max-width: 680px) {
  .inner,
  .container,
  .hero-content { width: min(100% - 28px, var(--site-width)); }

  .topbar .inner { display: grid; }
  .brand-title { font-size: 21px; }
  .brand-mark { width: 46px; height: 46px; }
  .main-nav { gap: 4px; }
  .main-nav a, .dropdown-title { font-size: 13px; padding: 8px 10px; }
  .dropdown-title { padding-right: 25px; }
  .dropdown-panel { top: 39px; }

  .home-hero { min-height: 580px; }
  .hero-content { padding: 74px 0; }
  .hero-meta { display: grid; grid-template-columns: 1fr; }
  .meta-card { min-width: 0; }

  .page-header { padding: 62px 0 58px; }
  .page-main { padding: 44px 0 60px; }
  .card { padding: 22px; }

  .gallery { grid-template-columns: 1fr; }
  .section-title { display: block; }
  .section-title p { margin-top: 10px; }

  table { display: block; overflow-x: auto; }
  th, td { min-width: 170px; }

  .history-meta { grid-template-columns: 1fr; }
  .history-photo-grid { grid-template-columns: 1fr; }
  .history-photo-grid figure.featured { grid-column: auto; }
  .history-photo-grid figure.featured img,
  .history-photo-grid img { height: auto; }
}