/* ============================================================
   BERGLABS LMS — DESIGN SYSTEM
   Glassmorphism · Blue · White · Grey · Coursera-style
   ============================================================ */

/* ----- CSS VARIABLES ----- */
:root {
  /* Primary palette */
  --navy: #0A1628;
  --dark-navy: #0D1F3C;
  --blue: #1A73E8;
  --blue-hover: #1557B0;
  --blue-light: #E8F0FE;
  --blue-glow: rgba(26, 115, 232, 0.12);
  --blue-dark: #0D47A1;

  /* Neutrals */
  --white: #FFFFFF;
  --glass-shadow: rgba(0, 0, 0, 0.06);
  --grey-50: #F8F9FA;
  --grey-100: #F1F3F4;
  --grey-200: #DADCE0;
  --grey-300: #BDC1C6;
  --grey-400: #9AA0A6;
  --grey-500: #5F6368;
  --grey-600: #3C4043;
  --grey-700: #202124;

  /* Semantic */
  --success: #34A853;
  --success-light: #E6F4EA;
  --warning: #FBBC04;
  --warning-light: #FFF8E1;
  --error: #EA4335;
  --error-light: #FCE8E6;
  --purple: #7C3AED;
  --purple-light: #F5F3FF;
  --teal: #0D9488;
  --teal-light: #F0FDF9;
  --orange: #FA7B17;
  --orange-light: #FFF3E0;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.12);
  --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.15);
  --shadow-glass: 0 8px 32px rgba(0, 0, 0, 0.08);

  /* Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Transitions */
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-fast: all 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);

  /* Typography */
  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', monospace;

  /* Layout */
  --max-width: 1200px;
  --sidebar-width: 280px;

  /* Glassmorphism */
  --glass-bg: rgba(255, 255, 255, 0.65);
  --glass-border: rgba(255, 255, 255, 0.25);
  --glass-blur: blur(16px);
}

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

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

body {
  font-family: var(--font);
  color: var(--grey-700);
  background: var(--grey-50);
  line-height: 1.6;
  overflow-x: hidden;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a:hover {
  color: var(--blue-hover);
}

button {
  cursor: pointer;
  font-family: var(--font);
  border: none;
  background: none;
  font-size: inherit;
}

img {
  max-width: 100%;
  display: block;
}

input,
select,
textarea {
  font-family: var(--font);
  font-size: inherit;
}

ul, ol {
  list-style: none;
}

/* ----- GLASS CARD MIXIN ----- */
.glass-card {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-glass);
  transition: var(--transition);
}

.glass-card:hover {
  box-shadow: var(--shadow-md);
  border-color: rgba(255, 255, 255, 0.4);
}

/* ----- BACKGROUND GRADIENT ----- */
.gradient-bg {
  background: linear-gradient(135deg, #f5f7fa 0%, #e4e9f2 50%, #dde3ed 100%);
  position: fixed;
  inset: 0;
  z-index: -1;
}

.gradient-bg::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(ellipse at 20% 50%, rgba(26, 115, 232, 0.06) 0%, transparent 50%),
              radial-gradient(ellipse at 80% 20%, rgba(124, 58, 237, 0.04) 0%, transparent 50%),
              radial-gradient(ellipse at 50% 80%, rgba(13, 148, 136, 0.04) 0%, transparent 50%);
  animation: gradientShift 15s ease-in-out infinite alternate;
}

@keyframes gradientShift {
  0% { transform: translate(0, 0) rotate(0deg); }
  100% { transform: translate(-5%, 5%) rotate(3deg); }
}

/* ----- KEYFRAMES ----- */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideInLeft {
  from { opacity: 0; transform: translateX(-20px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes scaleIn {
  from { opacity: 0; transform: scale(0.95); }
  to { opacity: 1; transform: scale(1); }
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.05); }
}

@keyframes shimmer {
  0% { background-position: -200% 0; }
  100% { background-position: 200% 0; }
}

@keyframes confetti {
  0% { transform: translateY(0) rotate(0deg); opacity: 1; }
  100% { transform: translateY(-200px) rotate(720deg); opacity: 0; }
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

/* ----- BUTTON SYSTEM ----- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 22px;
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 600;
  transition: var(--transition);
  border: none;
  cursor: pointer;
  line-height: 1.4;
  white-space: nowrap;
  user-select: none;
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: var(--blue);
  color: var(--white);
  box-shadow: 0 2px 8px rgba(26, 115, 232, 0.3);
}

.btn-primary:hover {
  background: var(--blue-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(26, 115, 232, 0.4);
}

.btn-success {
  background: var(--success);
  color: var(--white);
  box-shadow: 0 2px 8px rgba(52, 168, 83, 0.3);
}

.btn-success:hover {
  background: #2D8F47;
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(52, 168, 83, 0.4);
}

.btn-danger {
  background: var(--error);
  color: var(--white);
  box-shadow: 0 2px 8px rgba(234, 67, 53, 0.3);
}

.btn-danger:hover {
  background: #D93025;
  transform: translateY(-1px);
}

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

.btn-outline:hover {
  background: var(--blue-light);
  transform: translateY(-1px);
}

.btn-glass {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  color: var(--grey-700);
  border: 1px solid var(--glass-border);
}

.btn-glass:hover {
  background: rgba(255, 255, 255, 0.85);
  transform: translateY(-1px);
}

.btn-sm {
  padding: 6px 14px;
  font-size: 13px;
  border-radius: var(--radius-sm);
}

.btn-lg {
  padding: 14px 32px;
  font-size: 16px;
  border-radius: var(--radius-lg);
}

.btn-block {
  width: 100%;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none !important;
  box-shadow: none !important;
}

/* ----- INPUT SYSTEM ----- */
.input-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 16px;
}

.input-group label {
  font-size: 13px;
  font-weight: 600;
  color: var(--grey-600);
}

.input-field {
  padding: 12px 16px;
  border: 2px solid var(--grey-200);
  border-radius: var(--radius-md);
  font-size: 15px;
  color: var(--grey-700);
  background: var(--white);
  transition: var(--transition);
  outline: none;
  width: 100%;
}

.input-field:focus {
  border-color: var(--blue);
  box-shadow: 0 0 0 4px var(--blue-glow);
}

.input-field::placeholder {
  color: var(--grey-400);
}

.input-field.error {
  border-color: var(--error);
  box-shadow: 0 0 0 4px rgba(234, 67, 53, 0.1);
}

/* ----- BADGE SYSTEM ----- */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.badge-blue {
  background: var(--blue-light);
  color: var(--blue);
}

.badge-green {
  background: var(--success-light);
  color: var(--success);
}

.badge-red {
  background: var(--error-light);
  color: var(--error);
}

.badge-yellow {
  background: var(--warning-light);
  color: #B8860B;
}

.badge-purple {
  background: var(--purple-light);
  color: var(--purple);
}

.badge-teal {
  background: var(--teal-light);
  color: var(--teal);
}

/* ----- TOAST SYSTEM ----- */
.toast-container {
  position: fixed;
  top: 24px;
  right: 24px;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 8px;
  pointer-events: none;
}

.toast {
  pointer-events: auto;
  padding: 14px 20px;
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  animation: slideInLeft 0.3s ease;
  max-width: 400px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.toast-success {
  background: var(--success);
  color: white;
}

.toast-error {
  background: var(--error);
  color: white;
}

.toast-warning {
  background: var(--warning);
  color: var(--grey-700);
}

.toast-info {
  background: var(--blue);
  color: white;
}

.toast-removing {
  animation: fadeIn 0.3s ease reverse;
}

/* ----- LOADING SPINNER ----- */
.spinner {
  width: 20px;
  height: 20px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}

.spinner-dark {
  border-color: rgba(0, 0, 0, 0.1);
  border-top-color: var(--blue);
}

/* ----- EMPTY STATE ----- */
.empty-state {
  text-align: center;
  padding: 60px 20px;
}

.empty-state .empty-icon {
  font-size: 48px;
  margin-bottom: 16px;
}

.empty-state h3 {
  font-size: 20px;
  font-weight: 700;
  color: var(--grey-700);
  margin-bottom: 8px;
}

.empty-state p {
  font-size: 15px;
  color: var(--grey-500);
  max-width: 400px;
  margin: 0 auto;
}

/* ----- SCROLLBAR ----- */
::-webkit-scrollbar {
  width: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--grey-300);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--grey-400);
}