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

:root {
  --primary: #0d7377;
  --primary-dark: #095355;
  --primary-light: #14a3a8;
  --accent: #ff6f3c;
  --accent-light: #ff9a6c;
  --bg: #f7f9fc;
  --bg-white: #ffffff;
  --text: #2d3436;
  --text-light: #636e72;
  --text-lighter: #b2bec3;
  --border: #dfe6e9;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.12);
  --radius: 12px;
  --radius-sm: 8px;
  --transition: 0.3s ease;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  font-size: 16px;
}

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

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

img {
  max-width: 100%;
  height: auto;
}

/* ===== Navigation ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 2rem;
  height: 70px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: box-shadow var(--transition);
}

.navbar.scrolled {
  box-shadow: var(--shadow);
}

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

.nav-brand i {
  font-size: 1.4rem;
}

.nav-links {
  display: flex;
  gap: 0;
  list-style: none;
}

.nav-links li a {
  display: block;
  padding: 0.5rem 1.25rem;
  font-weight: 500;
  font-size: 0.95rem;
  color: var(--text);
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

.nav-links li a:hover,
.nav-links li a.active {
  color: var(--primary);
  background: rgba(13, 115, 119, 0.08);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text);
  cursor: pointer;
}

/* ===== Hero Section ===== */
.hero {
  min-height: 520px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 120px 2rem 60px;
  background: linear-gradient(135deg, #0d7377 0%, #14a3a8 40%, #32d9cb 100%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(255, 255, 255, 0.08) 0%, transparent 70%);
  border-radius: 50%;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -30%;
  left: -10%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(255, 111, 60, 0.12) 0%, transparent 70%);
  border-radius: 50%;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
}

.hero-badge {
  display: inline-block;
  background: rgba(255, 255, 255, 0.18);
  color: #fff;
  padding: 0.4rem 1.2rem;
  border-radius: 50px;
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.5px;
  margin-bottom: 1.5rem;
  backdrop-filter: blur(4px);
}

.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  color: #fff;
  line-height: 1.15;
  margin-bottom: 0.75rem;
}

.hero h1 span {
  color: var(--accent-light);
}

.hero .subtitle {
  font-size: 1.2rem;
  color: rgba(255, 255, 255, 0.9);
  font-weight: 400;
  margin-bottom: 0.5rem;
}

.hero .conference-info {
  font-size: 1rem;
  color: rgba(255, 255, 255, 0.75);
  margin-top: 1rem;
}

.hero .conference-info a {
  color: #fff;
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.hero .conference-info a:hover {
  color: var(--accent-light);
}

/* ===== Section Styles ===== */
.section {
  padding: 80px 2rem;
}

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

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

.section-title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 0.5rem;
}

.section-title i {
  color: var(--primary);
  margin-right: 0.5rem;
}

.section-divider {
  width: 60px;
  height: 4px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  border-radius: 2px;
  margin-bottom: 2rem;
}

.section-text {
  font-size: 1.05rem;
  color: var(--text-light);
  line-height: 1.8;
  max-width: 900px;
}

/* ===== Topic Cards ===== */
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.topic-card {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.topic-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary), var(--primary-light));
  transform: scaleX(0);
  transition: transform var(--transition);
}

.topic-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
}

.topic-card:hover::before {
  transform: scaleX(1);
}

.topic-card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--primary-dark);
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.topic-card h3 i {
  color: var(--primary);
  font-size: 1.2rem;
}

.topic-card ul {
  list-style: none;
  padding: 0;
}

.topic-card ul li {
  padding: 0.35rem 0;
  padding-left: 1.25rem;
  position: relative;
  font-size: 0.93rem;
  color: var(--text-light);
  line-height: 1.6;
}

.topic-card ul li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.75rem;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--primary-light);
}

/* ===== Dates Section ===== */
.dates-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.25rem;
  margin-top: 2rem;
}

.date-card {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  text-align: center;
  transition: all var(--transition);
}

.date-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
  border-color: var(--primary-light);
}

.date-card .date-icon {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1rem;
  color: #fff;
  font-size: 1.2rem;
}

.date-card .date-label {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-lighter);
  font-weight: 600;
  margin-bottom: 0.4rem;
}

.date-card .date-value {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text);
}

/* ===== Submission Page ===== */
.submission-portal {
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  border-radius: var(--radius);
  padding: 2.5rem;
  text-align: center;
  margin-bottom: 2.5rem;
  color: #fff;
}

.submission-portal h3 {
  font-size: 1.5rem;
  margin-bottom: 0.75rem;
}

.submission-portal p {
  margin-bottom: 1.5rem;
  opacity: 0.9;
}

.btn {
  display: inline-block;
  padding: 0.75rem 2rem;
  border-radius: 50px;
  font-weight: 600;
  font-size: 1rem;
  transition: all var(--transition);
  cursor: pointer;
  border: none;
}

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

.btn-white:hover {
  background: var(--accent);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(255, 111, 60, 0.3);
}

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

.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
}

.guidelines-list {
  list-style: none;
  padding: 0;
}

.guidelines-list li {
  padding: 0.65rem 0;
  padding-left: 2rem;
  position: relative;
  color: var(--text-light);
  line-height: 1.7;
}

.guidelines-list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 1rem;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--primary);
}

.criteria-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}

.criteria-item {
  background: var(--bg);
  border-radius: var(--radius-sm);
  padding: 1rem 1.25rem;
  text-align: center;
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--primary-dark);
  border: 1px solid var(--border);
}

.criteria-item i {
  display: block;
  font-size: 1.4rem;
  color: var(--primary);
  margin-bottom: 0.5rem;
}

/* ===== Organizer Cards ===== */
.organizers-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(480px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.organizer-card {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  transition: all var(--transition);
}

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

.organizer-header {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: 1.25rem;
}

.organizer-avatar {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 1.6rem;
  font-weight: 700;
  flex-shrink: 0;
  overflow: hidden;
}

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

.organizer-info h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 0.2rem;
}

.organizer-info .affiliation {
  font-size: 0.9rem;
  color: var(--primary);
  font-weight: 500;
}

.organizer-info .email {
  font-size: 0.85rem;
  color: var(--text-light);
}

.organizer-bio {
  font-size: 0.92rem;
  color: var(--text-light);
  line-height: 1.7;
}

/* ===== TPC Section ===== */
.tpc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 0.75rem;
  margin-top: 1.5rem;
}

.tpc-member {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 1.25rem;
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

.tpc-member:hover {
  border-color: var(--primary-light);
  background: rgba(13, 115, 119, 0.03);
}

.tpc-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--primary-light);
  flex-shrink: 0;
}

.tpc-member .name {
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text);
}

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

/* ===== Footer ===== */
.footer {
  background: var(--primary-dark);
  color: rgba(255, 255, 255, 0.8);
  text-align: center;
  padding: 2.5rem 2rem;
}

.footer p {
  font-size: 0.9rem;
  margin-bottom: 0.35rem;
}

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

.footer a:hover {
  color: #fff;
}

.footer .footer-links {
  margin-top: 1rem;
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.footer .footer-links a {
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.85rem;
  font-weight: 500;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 70px;
    left: 0;
    right: 0;
    background: var(--bg-white);
    flex-direction: column;
    padding: 1rem;
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow);
  }

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

  .nav-toggle {
    display: block;
  }

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

  .hero .subtitle {
    font-size: 1rem;
  }

  .hero {
    min-height: 400px;
    padding: 100px 1.5rem 50px;
  }

  .section {
    padding: 50px 1.25rem;
  }

  .section-title {
    font-size: 1.5rem;
  }

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

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

  .dates-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 480px) {
  .dates-grid {
    grid-template-columns: 1fr;
  }
}

/* ===== Info box ===== */
.info-box {
  background: rgba(13, 115, 119, 0.06);
  border-left: 4px solid var(--primary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 1.25rem 1.5rem;
  margin: 1.5rem 0;
}

.info-box p {
  font-size: 0.95rem;
  color: var(--text-light);
  line-height: 1.7;
}

/* ===== Review Process ===== */
.review-process {
  background: var(--bg);
  border-radius: var(--radius);
  padding: 2rem;
  margin-top: 2rem;
}

.review-process h3 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--primary-dark);
  margin-bottom: 1rem;
}

.review-process p {
  font-size: 0.95rem;
  color: var(--text-light);
  line-height: 1.8;
}