/* ============================================================
   LeetCode Visualiser — Design System
   Dark-first, responsive, premium dashboard UI
   ============================================================ */

/* --- Google Fonts --- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

/* ============================================================
   CSS Custom Properties (Dark Theme — default)
   ============================================================ */
:root {
  /* Backgrounds */
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-card: #1e293b;
  --bg-card-hover: #253349;
  --bg-surface: #334155;
  --bg-input: #1e293b;
  --bg-navbar: rgba(15, 23, 42, 0.85);

  /* Accent */
  --accent: #6366f1;
  --accent-hover: #818cf8;
  --accent-glow: rgba(99, 102, 241, 0.25);
  --accent-subtle: rgba(99, 102, 241, 0.08);

  /* Text */
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --text-inverse: #0f172a;

  /* Borders */
  --border: rgba(148, 163, 184, 0.12);
  --border-hover: rgba(148, 163, 184, 0.25);

  /* Difficulty colors */
  --easy: #00b8a3;
  --medium: #ffc01e;
  --hard: #ef4743;

  /* Chart colors */
  --chart-blue: #6366f1;
  --chart-cyan: #06b6d4;
  --chart-emerald: #10b981;
  --chart-amber: #f59e0b;
  --chart-rose: #f43f5e;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.25);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.3);
  --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.2);
  --shadow-card-hover: 0 8px 24px rgba(0, 0, 0, 0.35);

  /* Spacing */
  --gap: 24px;
  --gap-sm: 16px;
  --radius: 16px;
  --radius-sm: 12px;
  --radius-xs: 8px;

  /* Layout */
  --container-max: 1200px;
  --navbar-height: 56px;
  --chart-max-height: 320px;
}

/* ============================================================
   Light Theme
   ============================================================ */
[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-card: #ffffff;
  --bg-card-hover: #f1f5f9;
  --bg-surface: #e2e8f0;
  --bg-input: #ffffff;
  --bg-navbar: rgba(248, 250, 252, 0.85);

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --text-inverse: #f1f5f9;

  --border: rgba(15, 23, 42, 0.08);
  --border-hover: rgba(15, 23, 42, 0.16);

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.1);
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-card-hover: 0 4px 16px rgba(0, 0, 0, 0.1);

  --accent-glow: rgba(99, 102, 241, 0.15);
  --accent-subtle: rgba(99, 102, 241, 0.06);
}

/* ============================================================
   Reset & Base
   ============================================================ */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s;
}
a:hover { color: var(--accent-hover); }

img { max-width: 100%; height: auto; }

h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  color: var(--text-primary);
}

/* ============================================================
   Container
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--gap);
}

/* ============================================================
   Navbar
   ============================================================ */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--navbar-height);
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  will-change: transform;
}

.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--gap-sm);
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 1rem;
  color: var(--text-primary);
  white-space: nowrap;
  text-decoration: none;
}

.navbar-brand svg {
  width: 22px;
  height: 22px;
  color: var(--accent);
}

.navbar-search {
  flex: 1;
  max-width: 420px;
}

.navbar-search form {
  display: flex;
  align-items: center;
  gap: 8px;
}

.navbar-search input {
  width: 100%;
  height: 36px;
  padding: 0 12px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-xs);
  color: var(--text-primary);
  font-size: 0.8125rem;
  font-family: inherit;
  transition: border-color 0.2s, box-shadow 0.2s;
  outline: none;
}

.navbar-search input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.navbar-search input::placeholder {
  color: var(--text-muted);
}

.navbar-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 16px;
  font-family: inherit;
  font-size: 0.8125rem;
  font-weight: 500;
  line-height: 1;
  border: 1px solid transparent;
  border-radius: var(--radius-xs);
  cursor: pointer;
  transition: all 0.2s;
  white-space: nowrap;
  text-decoration: none;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.btn-primary:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  box-shadow: 0 2px 8px var(--accent-glow);
  color: #fff;
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border-color: var(--border);
}
.btn-ghost:hover {
  background: var(--bg-card);
  color: var(--text-primary);
  border-color: var(--border-hover);
}

.btn-icon {
  width: 36px;
  height: 36px;
  padding: 0;
  border-radius: var(--radius-xs);
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s, color 0.2s, border-color 0.2s;
  font-size: 1rem;
}
.btn-icon:hover {
  background: var(--bg-card);
  color: var(--text-primary);
  border-color: var(--border-hover);
}

.btn-lg {
  padding: 12px 24px;
  font-size: 0.9375rem;
  border-radius: var(--radius-sm);
}

/* ============================================================
   Grid System (12-column)
   ============================================================ */
.grid {
  display: grid;
  gap: var(--gap);
}

.grid-cols-1 { grid-template-columns: 1fr; }
.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

.col-span-full { grid-column: 1 / -1; }

/* ============================================================
   Cards
   ============================================================ */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--gap);
  box-shadow: var(--shadow-card);
  transition: border-color 0.2s;
}

.card:hover {
  border-color: var(--border-hover);
}

/* Stat Cards */
.stat-card {
  display: flex;
  align-items: center;
  gap: var(--gap-sm);
  padding: 20px;
  position: relative;
  overflow: hidden;
}

.stat-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: linear-gradient(135deg, var(--accent-subtle) 0%, transparent 60%);
  pointer-events: none;
}

.stat-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.125rem;
  background: var(--accent-subtle);
  color: var(--accent);
  flex-shrink: 0;
}

.stat-icon.green { background: rgba(0, 184, 163, 0.1); color: var(--easy); }
.stat-icon.amber { background: rgba(245, 158, 11, 0.1); color: var(--chart-amber); }
.stat-icon.rose { background: rgba(244, 63, 94, 0.1); color: var(--chart-rose); }

.stat-content {
  display: flex;
  flex-direction: column;
  gap: 2px;
  min-width: 0;
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
}

.stat-label {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* Chart Cards */
.chart-card {
  padding: var(--gap);
}

.chart-card .chart-title {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: var(--gap-sm);
}

.chart-wrapper {
  width: 100%;
  max-height: var(--chart-max-height);
  min-height: 200px;
}

.chart-wrapper .apexcharts-canvas {
  max-height: var(--chart-max-height) !important;
}

/* ============================================================
   Profile Header
   ============================================================ */
.profile-header {
  display: flex;
  align-items: center;
  gap: var(--gap);
  padding: var(--gap) 0;
  flex-wrap: wrap;
}

.profile-header-left {
  display: flex;
  align-items: center;
  gap: var(--gap);
}

.profile-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
}

.profile-avatar {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid var(--border);
  flex-shrink: 0;
}

.profile-info {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.profile-name {
  font-size: 1.25rem;
  font-weight: 700;
}

.profile-username {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.profile-link {
  font-size: 0.75rem;
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

/* ============================================================
   Hero / Landing
   ============================================================ */
.hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - var(--navbar-height) - 200px);
  text-align: center;
  padding: 60px var(--gap);
}

.hero-title {
  font-size: 2.25rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--accent) 0%, var(--chart-cyan) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 12px;
}

.hero-subtitle {
  font-size: 1rem;
  color: var(--text-secondary);
  max-width: 480px;
  margin-bottom: 32px;
}

.hero-form {
  display: flex;
  gap: 8px;
  width: 100%;
  max-width: 460px;
}

.hero-form input {
  flex: 1;
  height: 44px;
  padding: 0 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 0.875rem;
  font-family: inherit;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.hero-form input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.hero-form input::placeholder {
  color: var(--text-muted);
}

.hero-actions {
  display: flex;
  gap: 12px;
  margin-top: 16px;
}

/* Feature Cards */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--gap);
  max-width: 900px;
  margin: 48px auto 0;
}

.feature-card {
  text-align: center;
  padding: 32px 24px;
}

.feature-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  margin-bottom: 16px;
  background: var(--accent-subtle);
  color: var(--accent);
}

.feature-card h3 {
  font-size: 0.9375rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* ============================================================
   Dashboard Section
   ============================================================ */
.dashboard {
  padding: 32px 0 64px;
}

.section-title {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: var(--gap-sm);
}

/* Badges Grid */
.badges-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.badge-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  padding: 12px 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  min-width: 90px;
  cursor: default;
  transition: border-color 0.2s;
}

.badge-item:hover {
  border-color: var(--accent);
}

.badge-icon {
  width: 48px;
  height: 48px;
  object-fit: contain;
}

.badge-name {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-align: center;
  max-width: 100px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* Contest stats badges */
.contest-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: var(--gap-sm);
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 4px 10px;
  font-size: 0.75rem;
  font-weight: 500;
  border-radius: 6px;
  background: var(--bg-surface);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.badge.green { color: var(--easy); border-color: rgba(0, 184, 163, 0.3); }
.badge.red { color: var(--hard); border-color: rgba(239, 71, 67, 0.3); }

/* ============================================================
   Compare Page
   ============================================================ */
.compare-form-section {
  padding: 40px 0;
}

.compare-inputs {
  display: flex;
  align-items: center;
  gap: 12px;
  max-width: 600px;
  margin: 0 auto;
}

.compare-inputs input {
  flex: 1;
  height: 44px;
  padding: 0 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 0.875rem;
  font-family: inherit;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.compare-inputs input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.compare-inputs input::placeholder {
  color: var(--text-muted);
}

.compare-vs {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  flex-shrink: 0;
}

.compare-profiles {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--gap);
  margin-bottom: var(--gap);
}

/* ============================================================
   Alert
   ============================================================ */
.alert-error {
  background: rgba(239, 71, 67, 0.1);
  border: 1px solid rgba(239, 71, 67, 0.3);
  color: var(--hard);
  padding: 12px 16px;
  border-radius: var(--radius-xs);
  font-size: 0.875rem;
  display: flex;
  align-items: center;
  gap: 8px;
  max-width: 600px;
  margin: var(--gap) auto;
}

/* ============================================================
   Footer
   ============================================================ */
.footer {
  border-top: 1px solid var(--border);
  padding: 24px 0;
  text-align: center;
  margin-top: 64px;
}

.footer p {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin: 0;
}

.footer a {
  color: var(--text-secondary);
}

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

/* ============================================================
   Loading Overlay
   ============================================================ */
#loading-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 9999;
  background: rgba(15, 23, 42, 0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.loading-content {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
}

.spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: 0 auto 16px;
}

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

.loading-content p {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

/* ============================================================
   Theme Toggle
   ============================================================ */
.theme-toggle .fa-sun { display: none; }
.theme-toggle .fa-moon { display: inline; }

[data-theme="light"] .theme-toggle .fa-sun { display: inline; }
[data-theme="light"] .theme-toggle .fa-moon { display: none; }

/* ============================================================
   No Data State
   ============================================================ */
.empty-state {
  text-align: center;
  padding: 40px 20px;
  color: var(--text-muted);
}

.empty-state i {
  font-size: 2rem;
  margin-bottom: 12px;
  opacity: 0.4;
}

.empty-state p {
  font-size: 0.875rem;
}

/* ============================================================
   Responsive Breakpoints
   ============================================================ */

/* Tablet */
@media (max-width: 1024px) {
  .grid-cols-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-cols-4 { grid-template-columns: repeat(2, 1fr); }
  .features-grid { grid-template-columns: repeat(2, 1fr); }
}

/* Mobile */
@media (max-width: 768px) {
  :root {
    --gap: 16px;
    --gap-sm: 12px;
    --navbar-height: 52px;
  }

  .navbar .container {
    flex-wrap: wrap;
    gap: 8px;
  }

  .navbar-search {
    order: 3;
    max-width: 100%;
    flex: 0 0 100%;
    display: none; /* Hidden on mobile nav, show in hero/compact form */
  }

  .grid-cols-2,
  .grid-cols-3,
  .grid-cols-4 {
    grid-template-columns: 1fr;
  }

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

  .hero-title { font-size: 1.75rem; }
  .hero-form { flex-direction: column; }

  .compare-inputs {
    flex-direction: column;
  }

  .compare-profiles {
    grid-template-columns: 1fr;
  }

  .profile-header {
    flex-direction: column;
    text-align: center;
  }

  .stat-value { font-size: 1.25rem; }
}

/* Small mobile */
@media (max-width: 400px) {
  :root {
    --gap: 12px;
  }

  .hero-title { font-size: 1.5rem; }

  .stat-card { padding: 16px; }
  .stat-icon { width: 38px; height: 38px; font-size: 1rem; }
  .stat-value { font-size: 1.125rem; }
}

/* Large Desktop */
@media (min-width: 1440px) {
  :root {
    --container-max: 1280px;
  }
}

/* ============================================================
   ApexCharts Overrides
   ============================================================ */
.apexcharts-tooltip {
  border: 1px solid var(--border) !important;
  background: var(--bg-card) !important;
  border-radius: 8px !important;
  box-shadow: var(--shadow-md) !important;
}

.apexcharts-tooltip-title {
  background: var(--bg-surface) !important;
  border-bottom: 1px solid var(--border) !important;
  color: var(--text-primary) !important;
  font-family: 'Inter', sans-serif !important;
}

.apexcharts-tooltip-text {
  font-family: 'Inter', sans-serif !important;
  color: var(--text-primary) !important;
}

.apexcharts-legend-text {
  font-family: 'Inter', sans-serif !important;
  color: var(--text-secondary) !important;
}

.apexcharts-xaxis-label,
.apexcharts-yaxis-label {
  fill: var(--text-muted) !important;
  font-family: 'Inter', sans-serif !important;
}

.apexcharts-gridline {
  stroke: var(--border) !important;
}

/* ============================================================
   Utility
   ============================================================ */
.text-center { text-align: center; }
.text-muted { color: var(--text-muted); }
.mt-sm { margin-top: var(--gap-sm); }
.mt { margin-top: var(--gap); }
.mb { margin-bottom: var(--gap); }
.mb-sm { margin-bottom: var(--gap-sm); }
.gap-sm { gap: var(--gap-sm); }
.hidden { display: none !important; }