html {
  scroll-behavior: smooth;
}

:root {
  --color-bg: #f3f4ff;
  --color-bg-alt: #e0f2fe;
  --color-primary: #6366f1;
  --color-primary-soft: #a5b4fc;
  --color-accent: #f97316;
  --color-text: #0f172a;
  --color-text-muted: #6b7280;
  --color-card: #ffffff;
  --color-border-soft: #e5e7eb;

  --radius-lg: 18px;
  --radius-xl: 24px;

  --shadow-soft: 0 10px 30px rgba(15, 23, 42, 0.08);
  --transition: 0.25s ease;
}

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

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: radial-gradient(circle at top left, var(--color-bg-alt), var(--color-bg));
  color: var(--color-text);
  line-height: 1.6;
}

.container {
  width: min(1120px, 100%);
  margin: 0 auto;
  padding: 0 1.5rem;
}

.navbar {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(14px);
  background: rgba(243, 244, 255, 0.9);
  border-bottom: 1px solid rgba(148, 163, 184, 0.25);
  transition: background 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}

.navbar.navbar-scrolled {
  box-shadow: 0 6px 20px rgba(15, 23, 42, 0.12);
  background: rgba(243, 244, 255, 0.96);
  border-bottom-color: rgba(148, 163, 184, 0.4);
}

.navbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.9rem 1.5rem;
}

.navbar-logo {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-weight: 800;
  letter-spacing: 0.03em;
  color: var(--color-primary);
}

.navbar-logo span {
  font-size: 1.1rem;
}

.navbar-tagline {
  font-size: 0.75rem;
  color: var(--color-text-muted);
}

.navbar-menu {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.navbar-menu a {
  text-decoration: none;
  font-size: 0.95rem;
  color: var(--color-text-muted);
  padding: 0.4rem 0.7rem;
  border-radius: 999px;
  transition: var(--transition);
}

.navbar-menu a:hover,
.navbar-menu a.active {
  background: rgba(99, 102, 241, 0.1);
  color: var(--color-primary);
}

.btn-small {
  padding: 0.4rem 0.95rem;
  border-radius: 999px;
  border: none;
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 600;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  color: white;
  box-shadow: 0 8px 20px rgba(99, 102, 241, 0.35);
  transition: var(--transition);
}

.btn-small:hover {
  transform: translateY(-1px) scale(1.01);
  box-shadow: 0 12px 30px rgba(79, 70, 229, 0.45);
}

.hero {
  padding: 3rem 0 2rem;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 2fr) minmax(0, 1.5fr);
  gap: 2rem;
  align-items: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  background: rgba(148, 163, 184, 0.12);
  color: var(--color-primary);
  font-size: 0.8rem;
  margin-bottom: 0.75rem;
}

.hero-title {
  font-size: clamp(2rem, 3vw, 2.6rem);
  font-weight: 800;
  letter-spacing: 0.01em;
  margin-bottom: 0.8rem;
}

.hero-title span {
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-subtitle {
  font-size: 0.98rem;
  color: var(--color-text-muted);
  max-width: 32rem;
  margin-bottom: 1.3rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  align-items: center;
}

.btn-primary {
  padding: 0.7rem 1.4rem;
  border-radius: 999px;
  border: none;
  cursor: pointer;
  font-size: 0.95rem;
  font-weight: 600;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  color: white;
  box-shadow: var(--shadow-soft);
  transition: var(--transition);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 18px 40px rgba(79, 70, 229, 0.38);
}

.btn-ghost {
  padding: 0.7rem 1.2rem;
  border-radius: 999px;
  border: 1px solid rgba(148, 163, 184, 0.6);
  cursor: pointer;
  background: rgba(248, 250, 252, 0.7);
  font-size: 0.9rem;
  color: var(--color-text-muted);
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  transition: var(--transition);
}

.btn-ghost:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: rgba(255, 255, 255, 0.95);
}

.hero-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 1.3rem;
  margin-top: 1.3rem;
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.hero-card {
  background: radial-gradient(circle at top, #eef2ff, #ffffff);
  border-radius: 26px;
  padding: 1.6rem 1.5rem;
  box-shadow: var(--shadow-soft);
  border: 1px solid rgba(148, 163, 184, 0.22);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.hero-card-title {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
}

.hero-chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.chip {
  font-size: 0.75rem;
  padding: 0.25rem 0.7rem;
  border-radius: 999px;
  background: rgba(99, 102, 241, 0.08);
  color: var(--color-primary);
}

.section {
  padding: 2.5rem 0;
}

.section-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.section-title {
  font-size: 1.3rem;
  font-weight: 700;
}

.section-subtitle {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.section-tag {
  font-size: 0.8rem;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.card-grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.4rem;
}

.card-grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.4rem;
}

.card {
  background: var(--color-card);
  border-radius: var(--radius-lg);
  padding: 1.1rem 1.2rem;
  border: 1px solid rgba(226, 232, 240, 0.9);
  box-shadow: 0 12px 24px rgba(15, 23, 42, 0.06);
  transition: var(--transition);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 18px 40px rgba(15, 23, 42, 0.14);
  border-color: rgba(129, 140, 248, 0.9);
}

.card-title {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.4rem;
}

.card-text {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.badge-soft {
  display: inline-block;
  font-size: 0.75rem;
  padding: 0.2rem 0.55rem;
  border-radius: 999px;
  background: rgba(251, 146, 60, 0.08);
  color: var(--color-accent);
  margin-bottom: 0.4rem;
}

.library-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.library-item {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(226, 232, 240, 0.9);
  box-shadow: var(--shadow-soft);
}

.library-item img {
  width: 100%;
  display: block;
  object-fit: cover;
  transition: var(--transition);
}

.library-item:hover img {
  transform: scale(1.04);
}

.library-caption {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 0.6rem 0.8rem;
  font-size: 0.8rem;
  background: linear-gradient(to top, rgba(15, 23, 42, 0.85), transparent);
  color: #f9fafb;
}

.lecturer-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) minmax(0, 2fr);
  gap: 1.8rem;
  align-items: flex-start;
}

.lecturer-photo-card {
  background: var(--color-card);
  border-radius: var(--radius-xl);
  padding: 1.2rem;
  box-shadow: var(--shadow-soft);
  border: 1px solid var(--color-border-soft);
  text-align: center;
}

.lecturer-photo-card img {
  width: 100%;
  border-radius: 18px;
  object-fit: cover;
  margin-bottom: 0.8rem;
}

.lecturer-name {
  font-weight: 700;
  font-size: 1.05rem;
  margin-bottom: 0.15rem;
}

.lecturer-role {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.lecturer-bio {
  background: rgba(255, 255, 255, 0.9);
  border-radius: var(--radius-xl);
  padding: 1.3rem 1.4rem;
  box-shadow: var(--shadow-soft);
  border: 1px solid rgba(148, 163, 184, 0.32);
  font-size: 0.92rem;
}

.course-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.3rem;
}

.course-card {
  background: var(--color-card);
  border-radius: var(--radius-lg);
  padding: 1.1rem 1.2rem;
  border: 1px solid rgba(226, 232, 240, 1);
  box-shadow: var(--shadow-soft);
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.course-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 18px 40px rgba(15, 23, 42, 0.14);
  border-color: rgba(129, 140, 248, 0.9);
}

.course-meta {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-bottom: 0.4rem;
}

.course-link {
  margin-top: 0.8rem;
  font-size: 0.85rem;
}

.course-link a {
  text-decoration: none;
  color: var(--color-primary);
  font-weight: 600;
}

.contact-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1.5fr);
  gap: 1.6rem;
}

.contact-card,
.contact-form-card {
  background: var(--color-card);
  border-radius: var(--radius-xl);
  padding: 1.3rem 1.4rem;
  border: 1px solid var(--color-border-soft);
  box-shadow: var(--shadow-soft);
}

.contact-item {
  display: flex;
  align-items: flex-start;
  gap: 0.7rem;
  margin-bottom: 0.8rem;
}

.contact-label {
  font-size: 0.85rem;
  font-weight: 600;
}

.contact-value {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.form-group {
  margin-bottom: 0.9rem;
}

.form-label {
  display: block;
  font-size: 0.85rem;
  margin-bottom: 0.25rem;
}

.form-input,
.form-textarea {
  width: 100%;
  border-radius: 12px;
  border: 1px solid rgba(148, 163, 184, 0.7);
  padding: 0.5rem 0.75rem;
  font-size: 0.9rem;
  font-family: inherit;
  outline: none;
  background: rgba(248, 250, 252, 0.9);
  transition: var(--transition);
}

.form-input:focus,
.form-textarea:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 1px rgba(129, 140, 248, 0.6);
  background: #ffffff;
}

.form-textarea {
  min-height: 120px;
  resize: vertical;
}

.footer {
  margin-top: 3rem;
  padding: 1.4rem 0 1.6rem;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  border-top: 1px solid rgba(148, 163, 184, 0.35);
  background: rgba(248, 250, 252, 0.85);
}

/* Scroll reveal animations */
.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.in-view {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 900px) {
  .hero-grid,
  .lecturer-layout,
  .contact-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .card-grid-3,
  .course-list,
  .library-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .navbar-inner {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.7rem;
  }
}

@media (max-width: 640px) {
  .card-grid-3,
  .course-list,
  .library-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .hero {
    padding-top: 2.2rem;
  }
}