:root {
  --biu-green: #004d40;
  --biu-green-light: #00695c;
  --bg-dark: #050816;
  --bg-light: #ffffff;
  --accent: #f97316;
  --accent-hover: #fb923c;
  --text-main: #111827;
  --text-muted: #4b5563;
  --border-subtle: #e5e7eb;
  --max-width: 960px;
  --radius: 12px;
  --shadow-soft: 0 16px 40px rgba(15, 23, 42, 0.12);
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  color: var(--text-main);
  background: var(--bg-light);
  line-height: 1.6;
  overflow-x: hidden;
}

/* ===== LOGO BAR ===== */
.logo-bar {
  background: #ffffff;
  padding: 12px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-subtle);
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
  gap: 20px;
}

.dept-text-link {
  text-decoration: none;
  flex: 1;
  min-width: 0;
  transition: opacity 0.2s ease;
}

.dept-text-link:hover {
  opacity: 0.7;
}

.dept-logo-text {
  font-size: 11px;
  line-height: 1.2;
  color: #374151;
  text-transform: uppercase;
  letter-spacing: 0.02em;
}

.dept-logo-text strong {
  display: block;
  font-size: 12px;
  color: var(--biu-green);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.dept-logo-text em {
  font-style: normal;
  color: #6b7280;
  font-size: 10px;
  display: block;
}

.dept-logo-text-right {
  text-align: right;
}

.biu-center-logo-link {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.biu-center-logo {
  height: 48px;
  width: auto;
  object-fit: contain;
}

/* ===== HERO ===== */
.hero {
  background: radial-gradient(ellipse at top, #004d40 0%, #050816 70%);
  color: #f9fafb;
  padding: 120px 24px 100px;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.03'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
  opacity: 0.4;
}

.hero-content {
  position: relative;
  max-width: var(--max-width);
  margin: 0 auto;
}

.hero .date {
  letter-spacing: 0.2em;
  text-transform: uppercase;
  font-size: 13px;
  color: #4db6ac;
  margin-bottom: 16px;
  font-weight: 500;
}

.hero h1 {
  font-size: clamp(2.8rem, 6vw, 4rem);
  margin: 0 0 16px;
  font-weight: 800;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, #ffffff 0%, #80cbc4 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero .subtitle {
  max-width: 600px;
  margin: 0 auto 36px;
  font-size: 17px;
  color: #d1d5db;
  line-height: 1.7;
}

.btn-primary {
  display: inline-block;
  padding: 13px 28px;
  border-radius: 999px;
  background: var(--accent);
  color: #ffffff;
  font-weight: 700;
  font-size: 15px;
  text-decoration: none;
  box-shadow: 0 8px 30px rgba(249, 115, 22, 0.35);
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
  letter-spacing: 0.01em;
}

.btn-primary:hover {
  transform: translateY(-2px);
  background: var(--accent-hover);
  box-shadow: 0 14px 40px rgba(249, 115, 22, 0.45);
}

.btn-secondary,
.btn-link-strong {
  display: inline-block;
  margin: 10px 8px 0;
  padding: 13px 28px;
  border-radius: 999px;
  font-weight: 800;
  font-size: 15px;
  text-decoration: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease, color 0.15s ease;
  letter-spacing: 0.01em;
}

.btn-secondary {
  background: #ffffff;
  color: var(--biu-green);
  border: 2px solid #ffffff;
  box-shadow: 0 10px 34px rgba(255, 255, 255, 0.22);
}

.btn-secondary:hover {
  transform: translateY(-2px);
  background: #ccfbf1;
  border-color: #ccfbf1;
  box-shadow: 0 14px 40px rgba(204, 251, 241, 0.32);
}

.btn-link-strong {
  background: transparent;
  color: #ffffff;
  border: 2px solid rgba(255, 255, 255, 0.65);
}

.btn-link-strong:hover {
  transform: translateY(-2px);
  background: rgba(255, 255, 255, 0.12);
  border-color: #ffffff;
}

.btn-large {
  padding: 16px 36px;
  font-size: 17px;
}

/* ===== SECTIONS ===== */
.section {
  padding: 80px 24px;
  max-width: var(--max-width);
  margin: 0 auto;
}

.section h2 {
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  margin: 0 0 16px;
  font-weight: 800;
  color: var(--biu-green);
  position: relative;
  display: inline-block;
}

.section h2::after {
  content: '';
  position: absolute;
  bottom: -8px;
  left: 0;
  width: 40px;
  height: 4px;
  background: var(--accent);
  border-radius: 2px;
}

.section > p {
  color: var(--text-muted);
  font-size: 17px;
  max-width: 760px;
  line-height: 1.8;
}

.section a {
  color: var(--biu-green-light);
  font-weight: 700;
}

.section-dark {
  max-width: none;
  background: var(--bg-dark);
  color: #f9fafb;
  text-align: center;
}

.section-dark h2 {
  color: #ffffff;
}

.section-dark h2::after {
  left: 50%;
  transform: translateX(-50%);
}

.section-dark > p {
  margin-left: auto;
  margin-right: auto;
  color: #d1d5db;
}

/* ===== SPONSORS ===== */
.sponsors {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 28px;
  margin-top: 32px;
}

.sponsor-card {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 112px;
  min-width: 220px;
  padding: 24px 28px;
  background: #050505;
  border-radius: 8px;
  box-shadow: var(--shadow-soft);
}

.sponsor-card-light {
  background: #ffffff;
  border: 1px solid var(--border-subtle);
}

.sponsor-tier {
  flex: 1;
  min-width: 200px;
}

.sponsor-tier h3 {
  font-size: 14px;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 16px;
}

.sponsor-logo {
  height: 48px;
  width: auto;
  max-width: 180px;
  object-fit: contain;
}

.sponsor-logo-wide {
  height: 64px;
  max-width: 320px;
}

/* ===== MENTORS ===== */
.mentor-logos {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 24px;
  margin-top: 32px;
}

.mentor-card {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 88px;
  padding: 18px 22px;
  background: #ffffff;
  border: 1px solid var(--border-subtle);
  border-radius: 8px;
  box-shadow: var(--shadow-soft);
}

.mentor-logo {
  height: 26px;
  width: auto;
  max-width: 112px;
  object-fit: contain;
}

.mentor-logo-wide {
  height: 32px;
  max-width: 148px;
}

/* ===== SCHEDULE ===== */
.schedule {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 32px;
  margin-top: 40px;
}

.schedule-day {
  border-left: 4px solid var(--accent);
  padding-left: 24px;
}

.schedule-day h3 {
  margin: 0 0 20px;
  color: var(--biu-green);
  font-size: 22px;
}

.schedule-item {
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: 16px;
  align-items: start;
  padding: 14px 0;
  border-bottom: 1px solid var(--border-subtle);
}

.schedule-item time {
  color: var(--accent);
  font-weight: 800;
}

.schedule-item p {
  margin: 0;
  color: var(--text-muted);
}

/* ===== GRID ===== */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 32px;
  margin-top: 40px;
}

.person {
  text-align: center;
}

.person-photo {
  width: 150px;
  height: 150px;
  border-radius: 50%;
  object-fit: cover;
  margin-bottom: 16px;
  border: 4px solid #f3f4f6;
}

.organizer-avatar {
  width: 80px;
  height: 80px;
  background: var(--biu-green);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  font-weight: bold;
  border-radius: 50%;
  margin: 0 auto 16px;
}

/* ===== FAQ ===== */
.faq {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 32px;
  margin-top: 40px;
}

.faq-item h3 {
  font-size: 18px;
  margin-bottom: 12px;
  color: var(--biu-green);
}

/* ===== FOOTER ===== */
.footer {
  padding: 64px 24px;
  background: #f9fafb;
  text-align: center;
  border-top: 1px solid var(--border-subtle);
}

.footer p {
  margin: 8px 0;
  color: var(--text-muted);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  html,
  body {
    width: 100%;
    max-width: 100%;
  }

  .logo-bar {
    flex-wrap: wrap;
    justify-content: center;
    padding: 16px;
    gap: 16px;
    width: 100%;
    max-width: 100vw;
    overflow: hidden;
  }
  
  .biu-center-logo-link {
    order: -1;
    width: 100%;
    margin-bottom: 4px;
  }
  
  .dept-text-link {
    flex: none;
    width: 100%;
    text-align: center;
  }

  .dept-logo-text strong {
    white-space: normal;
  }
  
  .dept-logo-text-right {
    text-align: center;
  }
  
  .hero {
    padding: 80px 24px;
    width: 100%;
    max-width: 100vw;
  }

  .hero-content,
  .section {
    width: 100%;
    max-width: 100vw;
  }

  .hero-content {
    width: calc(100vw - 80px);
  }

  .section {
    width: 100vw;
  }

  .hero h1 {
    font-size: 1.9rem;
    overflow-wrap: anywhere;
  }

  .hero h2 {
    font-size: 1.05rem;
    line-height: 1.35;
    max-width: calc(100vw - 80px);
    overflow-wrap: anywhere;
  }

  .hero p {
    font-size: 0.95rem;
    max-width: calc(100vw - 80px);
    overflow-wrap: anywhere;
  }

  .section > p,
  .section ul {
    width: calc(100vw - 80px);
    max-width: calc(100vw - 80px);
  }

  .section > p {
    font-size: 16px;
  }

  .section p,
  .section li {
    overflow-wrap: anywhere;
  }

  .btn-primary,
  .btn-secondary,
  .btn-link-strong {
    width: min(100%, 260px);
    text-align: center;
  }
}