/* css variables for consistent theming */
:root {
  --primary:    #5B21B6;
  --accent:     #8B5CF6;
  --bg:         #F9F9F9;
  --card-bg:    #FFFFFF;
  --text-dark:  #1A1A1A;
  --text-muted: #6B7280;
  --border:     #E5E7EB;
}

/* reset default browser margin and padding */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* base body styles */
body {
  font-family: 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text-dark);
  line-height: 1.6;
}

a { text-decoration: none; color: inherit; }

/* max width wrapper, centred on the page */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* navbar - sticks to top while scrolling */
.navbar {
  position: sticky;
  top: 0; z-index: 100;
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  height: 64px;
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--primary);
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 32px;
}

.nav-links a {
  color: var(--text-dark);
  font-size: 0.95rem;
  position: relative;
  transition: color 0.3s ease;
}

/* animated underline that grows on hover */
.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -3px; left: 0;
  width: 0; height: 2px;
  background: var(--primary);
  transition: width 0.3s ease;
}

.nav-links a:hover,
.nav-links a.active { color: var(--primary); font-weight: 600; }
.nav-links a:hover::after { width: 100%; }

/* hidden on desktop, shown on mobile */
.hamburger {
  display: none;
  background: none;
  border: none;
  font-size: 1.6rem;
  cursor: pointer;
  color: var(--text-dark);
}

/* purple gradient banner at the top of the page */
.page-header {
  background: linear-gradient(135deg, #3B0764, #7C3AED);
  color: #fff;
  text-align: center;
  padding: 60px 24px;
}

.page-header h1 {
  font-size: 2.5rem;
  margin-bottom: 12px;
}

.page-header p {
  font-size: 1.1rem;
  color: rgba(255,255,255,0.85);
}

/* row of category filter buttons */
.filter-bar {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  padding: 32px 0 8px;
}

/* individual filter pill button */
.pill {
  padding: 8px 20px;
  border-radius: 999px;
  border: 2px solid var(--primary);
  background: transparent;
  color: var(--primary);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
}

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

/* currently selected filter pill */
.pill.active {
  background: var(--primary);
  color: #fff;
}

.classes-section {
  padding: 24px 0 60px;
}

/* responsive grid of class cards */
.class-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}

.class-card {
  background: var(--card-bg);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 2px 12px rgba(0,0,0,0.08);
  transition: all 0.3s ease;
  position: relative;
}

.class-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.14);
}

/* js adds this class to hide cards that don't match the active filter */
.class-card.hidden { display: none; }

/* image area at the top of each card */
.class-img {
  height: 200px;
  position: relative;
  overflow: hidden;
}

/* background images per class type, fallback colour if image fails to load */
.yoga-img {
  background: url('https://images.unsplash.com/photo-1544367567-0f2fcb009e0b?w=600&q=80&fit=crop') center/cover no-repeat;
  background-color: #00695C;
}

.cardio-img {
  background: url('https://images.unsplash.com/photo-1571019613454-1cb2f99b2d8b?w=600&q=80&fit=crop') center/cover no-repeat;
  background-color: #E65100;
}

.meditation-img {
  background: url('https://images.unsplash.com/photo-1506126613408-eca07ce68773?w=600&q=80&fit=crop') center/cover no-repeat;
  background-color: #4A148C;
}

.strength-img {
  background: url('https://images.unsplash.com/photo-1534438327276-14e5300c3a48?w=600&q=80&fit=crop') center/cover no-repeat;
  background-color: #B71C1C;
}

/* gradient overlay on the card image */
.card-img-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(to bottom,
    rgba(0,0,0,0.10) 0%,
    rgba(0,0,0,0.50) 100%);
  z-index: 1;
}

/* coloured difficulty badge in the top right corner of the image */
.difficulty-badge {
  position: absolute;
  top: 12px; right: 12px;
  z-index: 2;
  padding: 4px 10px;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
  color: #fff;
}

/* colour per difficulty level */
.difficulty-badge.beginner     { background: #5B21B6; }
.difficulty-badge.intermediate { background: #F57C00; }
.difficulty-badge.advanced     { background: #B71C1C; }

.class-body {
  padding: 20px;
}

.class-body h3 {
  font-size: 1.15rem;
  color: var(--text-dark);
  margin-bottom: 6px;
}

.class-body .meta {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.class-body .description {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin: 10px 0 18px;
}

/* button styles */
.btn {
  display: inline-block;
  padding: 10px 22px;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  border: 2px solid transparent;
}

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

.btn-primary:hover {
  background: #3B0764;
  transform: translateY(-2px);
}

/* footer */
.footer {
  background: var(--primary);
  color: #fff;
  text-align: center;
  padding: 24px;
  font-size: 0.9rem;
}

/* mobile styles - breakpoint at 768px */
@media (max-width: 768px) {
  .hamburger { display: block; }

  .nav-links {
    display: none;
    position: absolute;
    top: 64px; left: 0; right: 0;
    background: var(--card-bg);
    flex-direction: column;
    gap: 0;
    border-bottom: 1px solid var(--border);
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
  }

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

  .nav-links li a {
    display: block;
    padding: 14px 24px;
    border-bottom: 1px solid var(--border);
  }

  /* single column grid on mobile */
  .class-grid { grid-template-columns: 1fr; }

  .page-header h1 { font-size: 1.8rem; }
}