/* ==========================================================================
   AI & ROBOTICS CLUB - MAIN THEME STYLESHEET (style.css)
   Target Audience: Ages 8-16 & Parents
   ========================================================================== */

/* 1. Global CSS Variables (Theme Configuration) */
:root {
  /* Brand Colors */
  --primary-dark: #0f172a;
  --primary-blue: #2563eb;
  --accent-cyan: #06b6d4;
  --accent-purple: #6366f1;
  --accent-amber: #f59e0b;
  
  /* Neutral Palette */
  --bg-light: #f8fafc;
  --card-bg: #ffffff;
  --text-main: #1e293b;
  --text-muted: #64748b;
  --text-light: #f8fafc;

  /* UI Measurements & Effects */
  --border-radius-sm: 8px;
  --border-radius-md: 14px;
  --border-radius-lg: 24px;
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 10px 25px -5px rgba(15, 23, 42, 0.08);
  --shadow-glow: 0 0 20px rgba(6, 182, 212, 0.35);
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
}

/* 2. Base Reset & Layout Setup */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background-color: var(--bg-light);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* 3. Universal Typography */
h1, h2, h3, h4, h5, h6 {
  color: var(--primary-dark);
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -0.02em;
}

h1 { font-size: 2.75rem; }
h2 { font-size: 2.15rem; }
h3 { font-size: 1.5rem; }

p {
  color: var(--text-muted);
  margin-bottom: 1rem;
}

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

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

.gradient-text {
  background: linear-gradient(135deg, var(--primary-blue), var(--accent-cyan));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* 4. Common Reusable Components */
.container {
  width: 90%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

.section {
  padding: 5rem 0;
}

.text-center {
  text-align: center;
}

.section-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 3rem auto;
}

.section-header .tag {
  display: inline-block;
  background: rgba(37, 99, 235, 0.1);
  color: var(--primary-blue);
  padding: 0.35rem 1rem;
  border-radius: 50px;
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 0.75rem;
}

/* 5. Buttons & Interactivity */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.85rem 1.75rem;
  font-size: 1rem;
  font-weight: 700;
  border-radius: var(--border-radius-md);
  border: none;
  cursor: pointer;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), background-color var(--transition-fast);
  text-decoration: none;
}

.btn-primary {
  background-color: var(--accent-amber);
  color: var(--primary-dark);
  box-shadow: 0 4px 14px rgba(245, 158, 11, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(245, 158, 11, 0.45);
  color: var(--primary-dark);
}

.btn-secondary {
  background-color: var(--primary-blue);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.3);
}

.btn-secondary:hover {
  background-color: #1d4ed8;
  transform: translateY(-2px);
  color: #ffffff;
  box-shadow: var(--shadow-glow);
}

.btn-outline {
  background: transparent;
  border: 2px solid var(--primary-blue);
  color: var(--primary-blue);
}

.btn-outline:hover {
  background: var(--primary-blue);
  color: #ffffff;
}

/* 6. Card Components & Grid */
.grid {
  display: grid;
  gap: 2rem;
}

.grid-3 {
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.grid-2 {
  grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
}

.card {
  background-color: var(--card-bg);
  border-radius: var(--border-radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-md);
  border: 1px solid rgba(226, 232, 240, 0.8);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 20px 35px -10px rgba(15, 23, 42, 0.12), var(--shadow-glow);
}

.card-badge {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.25rem 0.75rem;
  border-radius: 50px;
  background-color: #e0f2fe;
  color: #0369a1;
  margin-bottom: 1rem;
}

/* 7. Header & Navigation - WHITE BACKGROUND */
.navbar {
  background-color: #ffffff;
  padding: 0.75rem 0;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 1px 8px rgba(0, 0, 0, 0.08);
  border-bottom: 1px solid #e2e8f0;
}

.navbar .nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

/* Logo - left side */
.navbar .logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  flex-shrink: 0;
}

.navbar .logo-img {
  height: 40px;
  width: auto;
  object-fit: contain;
}

.navbar .logo-text {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--primary-dark);
}

.navbar .logo-text span {
  color: var(--primary-blue);
}

/* Desktop nav - right side */
.nav-menu {
  display: flex;
  align-items: center;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 1.5rem;
  align-items: center;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--text-main);
  font-weight: 600;
  font-size: 14px;
  text-decoration: none;
  transition: color var(--transition-fast);
}

.nav-links a:hover {
  color: var(--primary-blue);
}

.nav-links .nav-cta {
  padding: 0.45rem 1rem !important;
  font-size: 14px !important;
  border-radius: 8px;
}

/* Hamburger button - hidden on desktop */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
}

.nav-toggle:hover {
  background: #f1f5f9;
}

.hamburger,
.hamburger::before,
.hamburger::after {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--primary-dark);
  border-radius: 2px;
  transition: all 0.25s ease;
  position: relative;
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  left: 0;
}

.hamburger::before {
  top: -7px;
}

.hamburger::after {
  top: 7px;
}

/* Hamburger open state (X) */
.nav-toggle.active .hamburger {
  background: transparent;
}

.nav-toggle.active .hamburger::before {
  top: 0;
  transform: rotate(45deg);
}

.nav-toggle.active .hamburger::after {
  top: 0;
  transform: rotate(-45deg);
}

/* 8. Footer */
.footer {
  background-color: var(--primary-dark);
  color: var(--text-light);
  padding: 4rem 0 2rem 0;
  margin-top: 4rem;
}

.footer p {
  color: #94a3b8;
}

.footer-bottom {
  text-align: center;
  padding-top: 2rem;
  margin-top: 3rem;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  font-size: 0.875rem;
  color: #64748b;
}

/* 9. Responsive - Mobile */
@media (max-width: 768px) {
  h1 { font-size: 2.1rem; }
  h2 { font-size: 1.75rem; }

  .nav-toggle {
    display: flex;
  }

  .nav-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #ffffff;
    border-bottom: 1px solid #e2e8f0;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.08);
    padding: 1rem 0;
  }

  .nav-menu.open {
    display: block;
  }

  .nav-links {
    flex-direction: column;
    gap: 0;
    align-items: stretch;
  }

  .nav-links li {
    border-bottom: 1px solid #f1f5f9;
  }

  .nav-links li:last-child {
    border-bottom: none;
  }

  .nav-links a {
    display: block;
    padding: 0.85rem 1.5rem;
    font-size: 14px;
  }

  .nav-links .nav-cta {
    margin: 0.75rem 1.5rem;
    text-align: center;
    display: block;
  }

  .navbar .logo-text {
    font-size: 1rem;
  }

  .grid-2 {
    grid-template-columns: 1fr;
  }

  .section {
    padding: 3rem 0;
  }

  /* Floating Cart Button */
  .cart-floating-btn {
    position: fixed;
    bottom: 24px;
    right: 24px;
    background-color: #0f172a;
    color: #ffffff;
    border: none;
    border-radius: 50px;
    padding: 12px 20px;
    font-size: 1rem;
    font-weight: bold;
    cursor: pointer;
    box-shadow: 0 4px 14px rgba(0,0,0,0.25);
    z-index: 998;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: transform 0.2s ease;
  }
  .cart-floating-btn:hover {
    transform: scale(1.05);
  }

  .cart-badge {
    background-color: #25D366;
    color: #ffffff;
    font-size: 0.8rem;
    padding: 2px 8px;
    border-radius: 12px;
  }

  .cart-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(0, 0, 0, 0.4);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
    z-index: 999;
  }
  .cart-overlay.active {
    opacity: 1;
    visibility: visible;
  }

  .cart-drawer {
    position: fixed;
    top: 0;
    right: -420px;
    width: 380px;
    max-width: 90vw;
    height: 100vh;
    background: #ffffff;
    box-shadow: -4px 0 20px rgba(0,0,0,0.15);
    display: flex;
    flex-direction: column;
    transition: right 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    z-index: 1000;
    font-family: Arial, sans-serif;
  }
  .cart-drawer.open {
    right: 0;
  }

  .cart-header {
    padding: 18px 20px;
    border-bottom: 1px solid #e2e8f0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: #f8fafc;
  }
  .cart-header h2 {
    margin: 0;
    font-size: 1.2rem;
    color: #0f172a;
  }
  .cart-close-btn {
    background: none;
    border: none;
    font-size: 1.8rem;
    line-height: 1;
    cursor: pointer;
    color: #64748b;
  }

  .cart-items-body {
    flex: 1;
    overflow-y: auto;
    padding: 16px;
  }

  .cart-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding-bottom: 12px;
    margin-bottom: 12px;
    border-bottom: 1px solid #f1f5f9;
  }
  .cart-item img {
    width: 55px;
    height: 55px;
    object-fit: cover;
    border-radius: 6px;
    background: #f1f5f9;
  }
  .cart-item-details {
    flex: 1;
  }
  .cart-item-title {
    font-weight: bold;
    font-size: 0.95rem;
    color: #0f172a;
    margin: 0 0 4px 0;
  }
  .cart-item-price {
    color: #475569;
    font-size: 0.85rem;
    margin: 0;
  }
  .cart-item-controls {
    display: flex;
    align-items: center;
    gap: 6px;
    margin-top: 6px;
  }
  .qty-btn {
    background: #e2e8f0;
    border: none;
    width: 24px;
    height: 24px;
    border-radius: 4px;
    cursor: pointer;
    font-weight: bold;
    line-height: 1;
  }
  .qty-number {
    font-size: 0.85rem;
    font-weight: bold;
    min-width: 18px;
    text-align: center;
  }
  .remove-item-btn {
    background: none;
    border: none;
    color: #ef4444;
    font-size: 0.8rem;
    cursor: pointer;
    margin-left: auto;
  }

  .cart-footer {
    padding: 16px 20px;
    border-top: 1px solid #e2e8f0;
    background: #f8fafc;
  }
  .cart-summary {
    display: flex;
    justify-content: space-between;
    font-size: 1.1rem;
    color: #0f172a;
    margin-bottom: 12px;
  }
  .cart-checkout-btn {
    width: 100%;
    background-color: #25D366;
    color: #ffffff;
    border: none;
    border-radius: 8px;
    padding: 12px;
    font-size: 1rem;
    font-weight: bold;
    cursor: pointer;
    margin-top: 10px;
    transition: background 0.2s ease;
  }
  .cart-checkout-btn:hover {
    background-color: #1da851;
  }
  .empty-cart-msg {
    text-align: center;
    color: #64748b;
    margin-top: 40px;
    font-size: 0.95rem;
  }
}