/* ===== Reset & Base ===== */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary: #0f2027;
  --primary-mid: #203a43;
  --primary-light: #2c5364;
  --accent: #00b4d8;
  --accent-light: #90e0ef;
  --accent-glow: rgba(0, 180, 216, 0.15);
  --text: #1a1a2e;
  --text-light: #555;
  --bg: #f8f9fc;
  --card-bg: #ffffff;
  --border: #e0e4ec;
  --radius: 12px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.06);
  --shadow-hover: 0 8px 32px rgba(0, 0, 0, 0.10);
  --font: 'Inter', 'Segoe UI', system-ui, -apple-system, sans-serif;
  --font-heading: 'Playfair Display', Georgia, serif;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  color: var(--primary-light);
}

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

/* ===== Typography ===== */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  color: var(--primary);
  line-height: 1.3;
}

/* Use serif font for ampersands */
.amp {
  font-family: 'Playfair Display', Georgia, 'Times New Roman', serif;
  font-style: italic;
}

h2.section-title {
  font-size: 2rem;
  margin-bottom: 0.5rem;
  position: relative;
  display: inline-block;
}

h2.section-title::after {
  content: '';
  position: absolute;
  bottom: -6px;
  left: 0;
  width: 60px;
  height: 3px;
  background: var(--accent);
  border-radius: 2px;
}

.section-subtitle {
  color: var(--text-light);
  font-size: 1.1rem;
  margin-bottom: 2.5rem;
}

/* ===== Navigation ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(15, 32, 39, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  transition: background 0.3s;
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 64px;
}

.nav-brand {
  font-family: var(--font-heading);
  font-size: 1.35rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: 1px;
}

.nav-brand span {
  color: var(--accent);
}

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

.nav-links a {
  color: rgba(255, 255, 255, 0.8);
  font-size: 0.95rem;
  font-weight: 500;
  padding: 0.4rem 0;
  position: relative;
  transition: color 0.2s;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: width 0.3s;
}

.nav-links a:hover,
.nav-links a.active {
  color: #fff;
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  width: 24px;
  height: 2px;
  background: #fff;
  border-radius: 2px;
  transition: transform 0.3s;
}

/* ===== Hero ===== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-mid) 50%, var(--primary-light) 100%);
  overflow: hidden;
  padding: 120px 2rem 80px;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 20% 50%, rgba(0, 180, 216, 0.08) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(144, 224, 239, 0.06) 0%, transparent 40%),
    radial-gradient(circle at 60% 80%, rgba(0, 180, 216, 0.05) 0%, transparent 45%);
  pointer-events: none;
}

/* Animated grid */
.hero::after {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 900px;
}

.hero-badge {
  display: inline-block;
  background: rgba(0, 180, 216, 0.15);
  border: 1px solid rgba(0, 180, 216, 0.3);
  color: var(--accent-light);
  padding: 0.5rem 1.5rem;
  border-radius: 50px;
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 1px;
  text-transform: uppercase;
  margin-bottom: 2rem;
}

.hero h1 {
  font-size: 3.5rem;
  color: #fff;
  margin-bottom: 0.75rem;
  letter-spacing: -0.5px;
}

.hero h1 .highlight {
  background: linear-gradient(135deg, var(--accent), var(--accent-light));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-full-title {
  font-size: 1.15rem;
  color: rgba(255, 255, 255, 0.7);
  margin-bottom: 1.5rem;
  font-weight: 400;
  max-width: 750px;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.6;
}

.hero-conference {
  font-size: 1.05rem;
  color: rgba(255, 255, 255, 0.6);
  margin-bottom: 2.5rem;
}

.hero-conference strong {
  color: var(--accent-light);
}

.hero-dates {
  display: flex;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.hero-dates-venue {
  margin-top: 0;
  margin-bottom: 2.5rem;
}

.hero-date-item {
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius);
  padding: 1.2rem 1.8rem;
  min-width: 200px;
  backdrop-filter: blur(4px);
}

.hero-date-item .label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 0.35rem;
}

.hero-date-item .date {
  font-size: 1rem;
  color: #fff;
  font-weight: 500;
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--accent);
  color: #fff;
  padding: 0.9rem 2.2rem;
  border-radius: 50px;
  font-weight: 600;
  font-size: 1rem;
  transition: transform 0.2s, box-shadow 0.2s;
  box-shadow: 0 4px 20px rgba(0, 180, 216, 0.3);
}

.hero-cta:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(0, 180, 216, 0.4);
  color: #fff;
}

/* ===== Sections ===== */
.section {
  padding: 5rem 2rem;
}

.section:nth-child(even) {
  background: #fff;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
}

/* ===== Scope ===== */
.scope-text {
  font-size: 1.08rem;
  color: var(--text-light);
  max-width: 900px;
  line-height: 1.85;
}

.scope-text p + p {
  margin-top: 1rem;
}

/* ===== Challenges ===== */
.challenges-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.5rem;
  margin-top: 1rem;
}

.challenge-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.8rem;
  transition: transform 0.2s, box-shadow 0.2s;
}

.challenge-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
}

.challenge-card .icon {
  width: 48px;
  height: 48px;
  background: var(--accent-glow);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  margin-bottom: 1rem;
}

.challenge-card h3 {
  font-size: 1.1rem;
  margin-bottom: 0.6rem;
  font-family: var(--font);
  font-weight: 600;
}

.challenge-card p {
  font-size: 0.95rem;
  color: var(--text-light);
  line-height: 1.65;
}

/* ===== Topics ===== */
.topics-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2rem;
}

.topic-group {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow);
}

.topic-group h3 {
  font-size: 1.2rem;
  margin-bottom: 1.2rem;
  padding-bottom: 0.8rem;
  border-bottom: 2px solid var(--accent-glow);
  font-family: var(--font);
  font-weight: 700;
  color: var(--primary);
}

.topic-group ul {
  list-style: none;
}

.topic-group li {
  position: relative;
  padding-left: 1.4rem;
  margin-bottom: 0.7rem;
  font-size: 0.95rem;
  color: var(--text-light);
  line-height: 1.55;
}

.topic-group li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.55rem;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
}

/* ===== Dates Table ===== */
.dates-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 1rem;
}

.dates-table th,
.dates-table td {
  text-align: left;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
}

.dates-table th {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-light);
  font-weight: 600;
}

.dates-table td {
  font-size: 1rem;
}

.dates-table td:first-child {
  font-weight: 600;
  color: var(--primary);
}

.dates-table tr:last-child td {
  border-bottom: none;
}

.dates-table .highlight-row td {
  background: var(--accent-glow);
  font-weight: 600;
}

/* ===== Submission Page ===== */
.page-hero {
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  padding: 140px 2rem 60px;
  text-align: center;
}

.page-hero h1 {
  color: #fff;
  font-size: 2.8rem;
  margin-bottom: 0.75rem;
}

.page-hero p {
  color: rgba(255, 255, 255, 0.7);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto;
}

.sub-types {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.sub-type-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  text-align: center;
  box-shadow: var(--shadow);
  transition: transform 0.2s;
}

.sub-type-card:hover {
  transform: translateY(-3px);
}

.sub-type-card .type-icon {
  font-size: 2.2rem;
  margin-bottom: 1rem;
}

.sub-type-card h3 {
  font-family: var(--font);
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.sub-type-card p {
  font-size: 0.92rem;
  color: var(--text-light);
}

.review-criteria {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}

.criteria-item {
  background: var(--accent-glow);
  border-radius: var(--radius);
  padding: 1.2rem;
  text-align: center;
  font-weight: 600;
  color: var(--primary);
  font-size: 0.95rem;
}

.submit-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--accent);
  color: #fff;
  padding: 1rem 2.4rem;
  border-radius: 50px;
  font-weight: 600;
  font-size: 1.05rem;
  transition: transform 0.2s, box-shadow 0.2s;
  box-shadow: 0 4px 20px rgba(0, 180, 216, 0.3);
  margin-top: 1.5rem;
}

.submit-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(0, 180, 216, 0.4);
  color: #fff;
}

/* ===== Organizers ===== */
.organizers-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(500px, 1fr));
  gap: 2rem;
}

.organizer-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow);
  display: flex;
  gap: 1.5rem;
  align-items: flex-start;
  transition: transform 0.2s;
}

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

.organizer-avatar {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-mid), var(--accent));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  color: #fff;
  font-weight: 700;
  font-family: var(--font-heading);
  flex-shrink: 0;
}

.organizer-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
}

.organizer-info h3 {
  font-family: var(--font);
  font-weight: 700;
  font-size: 1.15rem;
  margin-bottom: 0.25rem;
}

.organizer-role {
  font-size: 0.88rem;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 0.6rem;
}

.organizer-bio {
  font-size: 0.9rem;
  color: var(--text-light);
  line-height: 1.6;
}

.organizer-email {
  display: inline-block;
  margin-top: 0.5rem;
  font-size: 0.85rem;
  color: var(--accent);
  font-weight: 500;
}

/* PC Grid */
.pc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: 0.8rem;
}

.pc-member {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem 1.4rem;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.pc-member .pc-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  flex-shrink: 0;
}

.pc-member .pc-name {
  font-weight: 600;
  font-size: 0.95rem;
}

.pc-member .pc-role {
  font-size: 0.82rem;
  color: var(--text-light);
}

/* ===== Keynote Speaker ===== */
.keynote-card {
  background: linear-gradient(135deg, var(--primary-mid), var(--primary-light));
  border-radius: var(--radius);
  padding: 2.5rem;
  color: #fff;
  display: flex;
  gap: 2rem;
  align-items: center;
  box-shadow: var(--shadow);
}

.keynote-card .organizer-avatar {
  width: 100px;
  height: 100px;
  background: rgba(255,255,255,0.15);
  font-size: 2rem;
}

.keynote-card h3 {
  color: #fff;
  font-size: 1.35rem;
  margin-bottom: 0.3rem;
}

.keynote-card .organizer-role {
  color: var(--accent-light);
}

.keynote-card .organizer-bio {
  color: rgba(255,255,255,0.8);
}

/* ===== Footer ===== */
.footer {
  background: var(--primary);
  color: rgba(255, 255, 255, 0.6);
  text-align: center;
  padding: 3rem 2rem;
}

.footer-brand {
  font-family: var(--font-heading);
  font-size: 1.4rem;
  color: #fff;
  margin-bottom: 0.5rem;
}

.footer-brand span {
  color: var(--accent);
}

.footer p {
  font-size: 0.9rem;
  margin-bottom: 0.3rem;
}

.footer-links {
  margin-top: 1.5rem;
  display: flex;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
}

.footer-links a {
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.9rem;
  transition: color 0.2s;
}

.footer-links a:hover {
  color: var(--accent);
}

/* ===== Special Issue Banner ===== */
.special-issue {
  background: linear-gradient(135deg, var(--primary-mid), var(--primary-light));
  color: #fff;
  border-radius: var(--radius);
  padding: 2.5rem;
  margin-top: 2rem;
  text-align: center;
}

.special-issue h3 {
  color: #fff;
  font-size: 1.3rem;
  margin-bottom: 0.75rem;
}

.special-issue p {
  color: rgba(255, 255, 255, 0.8);
  max-width: 700px;
  margin: 0 auto;
  font-size: 1rem;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: rgba(15, 32, 39, 0.98);
    padding: 1.5rem 2rem;
    gap: 1rem;
  }

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

  .nav-toggle {
    display: flex;
  }

  .hero h1 {
    font-size: 2.2rem;
  }

  .hero-full-title {
    font-size: 1rem;
  }

  .hero-dates {
    flex-direction: column;
    align-items: center;
  }

  h2.section-title {
    font-size: 1.6rem;
  }

  .organizers-grid {
    grid-template-columns: 1fr;
  }

  .organizer-card {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }

  .page-hero h1 {
    font-size: 2rem;
  }

  .pc-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.8rem;
  }

  .section {
    padding: 3rem 1.2rem;
  }

  .challenges-grid,
  .topics-container {
    grid-template-columns: 1fr;
  }
}