/* Design System: Technical Minimalist / Mobile-First PWA */
:root {
  --bg-base: #09090b;
  --bg-surface: #121215;
  --bg-card: #18181b;
  --bg-card-hover: #222226;
  --border-subtle: #27272a;
  --border-active: #3f3f46;
  
  --text-primary: #f4f4f5;
  --text-secondary: #a1a1aa;
  --text-muted: #71717a;
  
  --accent-blue: #3b82f6;
  --accent-blue-hover: #2563eb;
  --accent-blue-glow: rgba(59, 130, 246, 0.15);
  
  --accent-green: #10b981;
  --accent-green-bg: rgba(16, 185, 129, 0.12);
  --accent-amber: #f59e0b;
  --accent-rose: #f43f5e;
  
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px 0 rgba(0, 0, 0, 0.4);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

body {
  background-color: var(--bg-base);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  padding-bottom: 72px; /* space for mobile bottom nav */
}

@media (min-width: 768px) {
  body {
    padding-bottom: 0;
  }
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}
::-webkit-scrollbar-track {
  background: var(--bg-base);
}
::-webkit-scrollbar-thumb {
  background: var(--border-subtle);
  border-radius: var(--radius-full);
}

/* Header */
.app-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background-color: rgba(9, 9, 11, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
  padding: 12px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand-badge {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text-primary);
}

.brand-icon {
  width: 34px;
  height: 34px;
  background: linear-gradient(135deg, #1e3a8a, #3b82f6);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 14px;
  color: #fff;
  box-shadow: 0 0 12px rgba(59, 130, 246, 0.3);
}

.brand-title {
  font-size: 16px;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.brand-subtitle {
  font-size: 11px;
  color: var(--text-secondary);
  font-family: var(--font-mono);
}

.header-user-status {
  display: flex;
  align-items: center;
  gap: 12px;
}

.band-chip {
  background: rgba(59, 130, 246, 0.12);
  border: 1px solid rgba(59, 130, 246, 0.3);
  color: var(--accent-blue);
  padding: 4px 10px;
  border-radius: var(--radius-full);
  font-size: 12px;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 6px;
}

.streak-chip {
  background: rgba(245, 158, 11, 0.12);
  border: 1px solid rgba(245, 158, 11, 0.3);
  color: var(--accent-amber);
  padding: 4px 10px;
  border-radius: var(--radius-full);
  font-size: 12px;
  font-weight: 600;
}

/* Container */
.main-container {
  max-width: 1080px;
  width: 100%;
  margin: 0 auto;
  padding: 20px 16px;
  flex: 1;
}

/* Bento Grid */
.bento-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

@media (min-width: 768px) {
  .bento-grid {
    grid-template-columns: repeat(12, 1fr);
  }
  .col-12 { grid-column: span 12; }
  .col-8 { grid-column: span 8; }
  .col-6 { grid-column: span 6; }
  .col-4 { grid-column: span 4; }
}

/* Cards */
.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 20px;
  position: relative;
  transition: transform 0.15s ease, border-color 0.15s ease;
}

.card-clickable:hover {
  border-color: var(--border-active);
  transform: translateY(-2px);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
}

.card-title {
  font-size: 16px;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px; /* WCAG touch target */
  padding: 10px 18px;
  font-size: 14px;
  font-weight: 600;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.15s ease;
  text-decoration: none;
}

.btn-primary {
  background-color: var(--accent-blue);
  color: #fff;
  border-color: rgba(255, 255, 255, 0.1);
  box-shadow: 0 2px 8px rgba(59, 130, 246, 0.35);
}

.btn-primary:hover {
  background-color: var(--accent-blue-hover);
}

.btn-secondary {
  background-color: var(--bg-surface);
  border-color: var(--border-subtle);
  color: var(--text-primary);
}

.btn-secondary:hover {
  background-color: var(--bg-card-hover);
  border-color: var(--border-active);
}

.btn-danger {
  background-color: rgba(244, 63, 94, 0.15);
  border-color: rgba(244, 63, 94, 0.4);
  color: var(--accent-rose);
}

/* Nav Tabs (Desktop) */
.desktop-nav {
  display: none;
  gap: 8px;
  background: var(--bg-surface);
  padding: 4px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-subtle);
  margin-bottom: 24px;
}

@media (min-width: 768px) {
  .desktop-nav {
    display: flex;
  }
}

.nav-tab {
  flex: 1;
  text-align: center;
  padding: 10px 14px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  cursor: pointer;
  border: none;
  background: transparent;
  transition: all 0.15s ease;
}

.nav-tab.active {
  background: var(--bg-card);
  color: var(--text-primary);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-subtle);
}

/* Bottom Nav (Mobile) */
.mobile-bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: 64px;
  background-color: rgba(9, 9, 11, 0.94);
  backdrop-filter: blur(16px);
  border-top: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-around;
  z-index: 50;
  padding: 0 8px;
}

@media (min-width: 768px) {
  .mobile-bottom-nav {
    display: none;
  }
}

.mobile-nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  min-width: 48px;
  height: 100%;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 10px;
  font-weight: 500;
  cursor: pointer;
  background: none;
  border: none;
}

.mobile-nav-item.active {
  color: var(--accent-blue);
}

.mobile-nav-item svg {
  width: 20px;
  height: 20px;
}

/* Timer Progress Ring & 60-Min Daily Protocol */
.timer-block-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  font-size: 11px;
  font-weight: 600;
  font-family: var(--font-mono);
}

.block-vocab { background: rgba(59, 130, 246, 0.15); color: #60a5fa; }
.block-grammar { background: rgba(16, 185, 129, 0.15); color: #34d399; }
.block-speaking { background: rgba(245, 158, 11, 0.15); color: #fbbf24; }
.block-review { background: rgba(168, 85, 247, 0.15); color: #c084fc; }

/* Micro-Drills and MCQ Cards */
.mcq-option {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 14px 16px;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  margin-bottom: 10px;
  cursor: pointer;
  transition: all 0.15s ease;
  min-height: 48px;
}

.mcq-option:hover {
  background-color: var(--bg-card-hover);
  border-color: var(--border-active);
}

.mcq-option.selected {
  background-color: rgba(59, 130, 246, 0.15);
  border-color: var(--accent-blue);
  color: #fff;
}

/* Chat bubble & Audio controls */
.chat-bubble {
  padding: 14px 18px;
  border-radius: var(--radius-lg);
  margin-bottom: 12px;
  font-size: 14px;
  line-height: 1.6;
}

.bubble-user {
  background-color: rgba(59, 130, 246, 0.15);
  border: 1px solid rgba(59, 130, 246, 0.3);
  align-self: flex-end;
  margin-left: 20%;
}

.bubble-assistant {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  align-self: flex-start;
  margin-right: 15%;
}

.native-pill {
  background: rgba(16, 185, 129, 0.1);
  border: 1px solid rgba(16, 185, 129, 0.3);
  padding: 8px 12px;
  border-radius: var(--radius-md);
  margin-top: 10px;
  font-size: 13px;
  color: #a7f3d0;
}

/* Voice Mic Pulse */
.mic-btn {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-full);
  background: var(--accent-blue);
  border: none;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  cursor: pointer;
  box-shadow: 0 0 16px rgba(59, 130, 246, 0.4);
  transition: transform 0.15s ease, background 0.15s ease;
}

.mic-btn.recording {
  background: var(--accent-rose);
  animation: pulse-ring 1.5s infinite;
}

@keyframes pulse-ring {
  0% { box-shadow: 0 0 0 0 rgba(244, 63, 94, 0.6); }
  70% { box-shadow: 0 0 0 16px rgba(244, 63, 94, 0); }
  100% { box-shadow: 0 0 0 0 rgba(244, 63, 94, 0); }
}

/* Modal */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 16px;
}

.modal-content {
  background: var(--bg-card);
  border: 1px solid var(--border-active);
  border-radius: var(--radius-lg);
  max-width: 520px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  padding: 24px;
}