/* ==========================================================================
   GLOBAL EDU PLATFORM — BASE & LAYOUT (layout.css)
   Mobile-first, zero horizontal overflow, flex/grid systems.
   ========================================================================== */

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

.hidden {
  display: none !important;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

/* Typography Base */
h1, h2, h3, h4, .font-display {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.2;
  color: var(--text);
}

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

button {
  font-family: inherit;
  border: none;
  background: none;
  cursor: pointer;
  color: inherit;
}

/* Header & Navbar */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background: rgba(15, 23, 42, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
}

.header-container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-4);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 800;
  color: var(--text);
}

.brand-badge {
  background: var(--primary);
  color: var(--text);
  font-size: var(--text-xs);
  padding: 2px 8px;
  border-radius: var(--radius-full);
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  list-style: none;
}

.nav-item a {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--text-muted);
  transition: color var(--duration-fast) ease;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm);
}

.nav-item a:hover,
.nav-item a.active {
  color: var(--text);
  background: var(--surface);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.btn-icon {
  width: 40px;
  height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text-muted);
  font-size: var(--text-base);
  transition: all var(--duration-fast) ease;
  user-select: none;
}

.btn-icon:hover {
  background: var(--surface-hover);
  color: var(--text);
}

.btn-lang {
  padding: 0 var(--space-3);
  height: 38px;
  font-size: var(--text-xs);
  font-weight: 700;
  border-radius: var(--radius-md);
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.btn-lang:hover {
  border-color: var(--primary);
}

/* Page Containers */
.main-content {
  flex: 1;
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: var(--space-6) var(--space-4);
}

/* Footer */
.site-footer {
  margin-top: auto;
  background: var(--bg-deep);
  border-top: 1px solid var(--border);
  padding: var(--space-8) var(--space-4) var(--space-6);
  color: var(--text-muted);
  font-size: var(--text-sm);
}

.footer-container {
  max-width: var(--container-max);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

.footer-top {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-6);
}

.footer-brand {
  max-width: 320px;
}

.footer-links-group {
  display: flex;
  gap: var(--space-8);
  flex-wrap: wrap;
}

.footer-col h4 {
  color: var(--text);
  font-size: var(--text-sm);
  margin-bottom: var(--space-3);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.footer-col ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.footer-col a:hover {
  color: var(--primary-light);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-3);
  padding-top: var(--space-4);
  border-top: 1px solid var(--border);
  font-size: var(--text-xs);
  color: var(--text-subtle);
}

/* Buttons System */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-md);
  font-family: var(--font-display);
  font-size: var(--text-base);
  font-weight: 700;
  text-align: center;
  transition: all var(--duration-fast) var(--ease-out);
  user-select: none;
  touch-action: manipulation;
}
.btn-primary { background: var(--primary); color: var(--text); box-shadow: 0 4px 14px var(--primary-glow); }
.btn-primary:hover { background: var(--primary-hover); transform: translateY(-2px); }
.btn-primary:active { transform: translateY(0); }
.btn-secondary { background: var(--secondary); color: var(--text); box-shadow: 0 4px 14px var(--secondary-glow); }
.btn-secondary:hover { background: var(--secondary-hover); transform: translateY(-2px); }
.btn-outline { background: transparent; border: 1px solid var(--border); color: var(--text); }
.btn-outline:hover { background: var(--surface); border-color: var(--text-muted); }

/* Responsive adjustments */
@media (max-width: 768px) {
  .header-container { padding: 0 var(--space-3); }
  .brand-logo { font-size: var(--text-base); }
  .brand-badge { font-size: 10px; padding: 1px 6px; }
  .btn-icon { width: 36px; height: 36px; }
  .btn-lang { height: 36px; padding: 0 var(--space-2); font-size: 11px; }
  .nav-links { display: none; }
  .main-content { padding: var(--space-4) var(--space-3); }
  .footer-top { flex-direction: column; }
}

/* Global Language Selector Modal */
.lang-modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(11, 15, 25, 0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: 500;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-4);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--duration-normal) ease;
}

.lang-modal-backdrop.active {
  opacity: 1;
  pointer-events: auto;
}

.lang-modal-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: var(--space-5);
  width: 100%;
  max-width: 580px;
  max-height: 85vh;
  overflow-y: auto;
  box-shadow: var(--shadow-lg);
  transform: scale(0.95);
  transition: transform var(--duration-normal) var(--ease-bounce);
}
.lang-modal-backdrop.active .lang-modal-box { transform: scale(1); }
.lang-modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-3);
  position: sticky;
  top: -10px;
  background: var(--surface);
  padding-bottom: var(--space-2);
  z-index: 2;
}
.lang-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: var(--space-2);
}
.lang-choice-card {
  background: var(--bg-deep);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 8px 12px;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  cursor: pointer;
  transition: all var(--duration-fast) ease;
  text-align: left;
}
.lang-choice-card:hover {
  background: var(--surface-hover);
  border-color: var(--primary);
  transform: translateY(-1px);
}
.lang-choice-card.active {
  border-color: var(--secondary);
  background: rgba(16, 185, 129, 0.14);
}
.lang-flag-badge {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 24px;
  background: rgba(99, 102, 241, 0.15);
  border: 1px solid rgba(99, 102, 241, 0.3);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 800;
  color: var(--primary-light);
  letter-spacing: 0.5px;
  flex-shrink: 0;
}
.lang-choice-card.active .lang-flag-badge {
  background: rgba(16, 185, 129, 0.2);
  border-color: var(--secondary);
  color: var(--secondary);
}
.lang-meta-name {
  font-size: 13px;
  font-weight: 700;
  color: var(--text);
  display: block;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.lang-meta-sub {
  font-size: 10px;
  color: var(--text-muted);
  display: block;
}