/* ==========================================================================
   VOCABMASTER DESIGN SYSTEM (Vanilla CSS)
   ========================================================================== */

:root {
  --bg-dark: #0b0f19;
  --bg-card: rgba(30, 41, 59, 0.7);
  --bg-card-hover: rgba(51, 65, 85, 0.8);
  --glass-border: rgba(255, 255, 255, 0.08);
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);

  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-dim: #64748b;

  --accent-primary: #6366f1; /* Indigo */
  --accent-primary-hover: #4f46e5;
  --accent-secondary: #06b6d4; /* Cyan */
  --accent-success: #10b981; /* Emerald */
  --accent-warning: #f59e0b; /* Amber */
  --accent-danger: #f43f5e; /* Rose */

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;

  --font-family: 'Noto Sans JP', 'Outfit', sans-serif;
  --transition-fast: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-dark);
  color: var(--text-main);
  min-height: 100vh;
  overflow-x: hidden;
  background-image: 
    radial-gradient(at 0% 0%, rgba(99, 102, 241, 0.15) 0px, transparent 50%),
    radial-gradient(at 100% 100%, rgba(6, 182, 212, 0.12) 0px, transparent 50%),
    radial-gradient(at 50% 50%, rgba(16, 185, 129, 0.08) 0px, transparent 50%);
  background-attachment: fixed;
}

/* App Container Layout */
.app-container {
  display: flex;
  min-height: 100vh;
}

/* Glassmorphism Utility */
.glass {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--glass-border);
  box-shadow: var(--glass-shadow);
  border-radius: var(--radius-md);
}

/* Sidebar Styles */
.sidebar {
  width: 280px;
  background: rgba(15, 23, 42, 0.85);
  border-right: 1px solid var(--glass-border);
  padding: 24px 16px;
  display: flex;
  flex-direction: column;
  gap: 24px;
  position: sticky;
  top: 0;
  height: 100vh;
  z-index: 10;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 0 8px;
}

.brand-icon {
  width: 44px;
  height: 44px;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  color: #fff;
  box-shadow: 0 4px 14px rgba(99, 102, 241, 0.4);
}

.brand-text h2 {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  background: linear-gradient(to right, #ffffff, #cbd5e1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.brand-text span {
  font-size: 0.75rem;
  color: var(--accent-secondary);
  font-weight: 600;
}

/* User Card */
.user-card {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
}

.avatar {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent-secondary), var(--accent-success));
  color: #fff;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
}

.user-info {
  display: flex;
  flex-direction: column;
  flex: 1;
  overflow: hidden;
}

.user-name {
  font-weight: 600;
  font-size: 0.9rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.user-role {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Navigation Menu */
.nav-menu {
  display: flex;
  flex-direction: column;
  gap: 6px;
  flex: 1;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px 16px;
  border-radius: var(--radius-md);
  border: none;
  background: transparent;
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition-fast);
  text-align: left;
}

.nav-item i {
  font-size: 1.1rem;
  width: 20px;
}

.nav-item:hover {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-main);
}

.nav-item.active {
  background: linear-gradient(90deg, rgba(99, 102, 241, 0.2), rgba(6, 182, 212, 0.1));
  border-left: 4px solid var(--accent-primary);
  color: #fff;
  font-weight: 700;
}

/* Status Badge */
.sheet-status-badge {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px;
  background: rgba(16, 185, 129, 0.08);
  border: 1px solid rgba(16, 185, 129, 0.2);
  border-radius: var(--radius-md);
  color: var(--accent-success);
}

.sheet-status-badge i {
  font-size: 1.2rem;
}

.status-info {
  display: flex;
  flex-direction: column;
}

.status-title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.status-sub {
  font-size: 0.8rem;
  color: var(--text-main);
  opacity: 0.9;
}

/* Main Content Layout */
.main-content {
  flex: 1;
  padding: 32px 40px;
  display: flex;
  flex-direction: column;
  gap: 28px;
  max-width: 1300px;
}

.top-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.header-left h1 {
  font-size: 1.8rem;
  font-weight: 800;
}

.header-left p {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-top: 4px;
}

.header-right {
  display: flex;
  gap: 12px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  border: none;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-fast);
  font-family: inherit;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-primary-hover));
  color: #fff;
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(99, 102, 241, 0.45);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-main);
  border: 1px solid var(--glass-border);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.15);
}

.btn-hero {
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  color: #fff;
  padding: 14px 28px;
  font-size: 1.05rem;
  border-radius: var(--radius-lg);
  box-shadow: 0 8px 24px rgba(99, 102, 241, 0.4);
}

.btn-hero:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 30px rgba(99, 102, 241, 0.55);
}

.btn-outline {
  background: transparent;
  border: 1px solid var(--accent-primary);
  color: var(--text-main);
  padding: 14px 28px;
  font-size: 1.05rem;
  border-radius: var(--radius-lg);
}

.btn-outline:hover {
  background: rgba(99, 102, 241, 0.15);
}

.btn-icon {
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 8px;
  border-radius: var(--radius-sm);
  transition: var(--transition-fast);
}

.btn-icon:hover {
  color: #fff;
  background: rgba(255, 255, 255, 0.1);
}

.btn-text {
  background: none;
  border: none;
  color: var(--accent-secondary);
  font-weight: 600;
  cursor: pointer;
}

/* Tabs Panel Display */
.tab-pane {
  display: none;
  animation: fadeIn 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.tab-pane.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  margin-bottom: 28px;
}

.stat-card {
  padding: 20px;
  display: flex;
  align-items: center;
  gap: 16px;
  position: relative;
  overflow: hidden;
}

.stat-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  background: rgba(255, 255, 255, 0.05);
}

.glow-indigo .stat-icon { color: var(--accent-primary); }
.glow-emerald .stat-icon { color: var(--accent-success); }
.glow-amber .stat-icon { color: var(--accent-warning); }
.glow-rose .stat-icon { color: var(--accent-danger); }

.stat-data {
  display: flex;
  flex-direction: column;
}

.stat-value {
  font-size: 1.8rem;
  font-weight: 800;
  line-height: 1.1;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 4px;
}

/* Dashboard Widgets */
.dashboard-widgets {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 24px;
  margin-bottom: 28px;
}

.widget {
  padding: 24px;
}

.widget h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.progress-bar-container {
  margin-bottom: 20px;
}

.progress-info {
  display: flex;
  justify-content: space-between;
  font-weight: 600;
  margin-bottom: 8px;
  font-size: 0.9rem;
}

.progress-track {
  height: 14px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 20px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-primary), var(--accent-success));
  border-radius: 20px;
  transition: width 0.6s ease;
}

.status-legend {
  display: flex;
  gap: 20px;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.badge {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.badge-unlearned { background: var(--text-dim); }
.badge-learning { background: var(--accent-warning); }
.badge-mastered { background: var(--accent-success); }

.quick-buttons {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

/* Library Search & Filter Bar */
.filter-bar {
  padding: 16px 20px;
  display: flex;
  gap: 16px;
  margin-bottom: 24px;
  align-items: center;
}

.search-box {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 12px;
  background: rgba(0, 0, 0, 0.2);
  padding: 10px 16px;
  border-radius: var(--radius-md);
  border: 1px solid var(--glass-border);
}

.search-box input {
  background: transparent;
  border: none;
  outline: none;
  color: var(--text-main);
  font-size: 0.95rem;
  width: 100%;
}

.filter-group {
  display: flex;
  gap: 12px;
}

.custom-select {
  background: rgba(15, 23, 42, 0.9);
  color: var(--text-main);
  border: 1px solid var(--glass-border);
  padding: 10px 16px;
  border-radius: var(--radius-md);
  outline: none;
  cursor: pointer;
}

/* Word Cards Grid */
.word-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}

.word-card {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: var(--transition-normal);
  position: relative;
}

.word-card:hover {
  transform: translateY(-4px);
  border-color: rgba(99, 102, 241, 0.4);
}

.card-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.word-category-tag {
  font-size: 0.75rem;
  background: rgba(99, 102, 241, 0.15);
  color: var(--accent-primary);
  padding: 4px 10px;
  border-radius: 20px;
  font-weight: 600;
}

.star-btn {
  background: none;
  border: none;
  color: var(--text-dim);
  font-size: 1.1rem;
  cursor: pointer;
  transition: var(--transition-fast);
}

.star-btn.active {
  color: var(--accent-warning);
}

.word-main h3 {
  font-size: 1.4rem;
  font-weight: 700;
}

.word-reading {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.word-meaning {
  font-size: 1rem;
  color: var(--text-main);
  margin-top: 4px;
}

.word-example {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-style: italic;
  background: rgba(0, 0, 0, 0.2);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--accent-secondary);
}

/* 3D Flashcard Section */
.flashcard-controls {
  padding: 16px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 32px;
}

.flashcard-container {
  perspective: 1000px;
  max-width: 600px;
  margin: 0 auto 32px auto;
  height: 340px;
  cursor: pointer;
}

.flashcard-3d {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.flashcard-3d.flipped {
  transform: rotateY(180deg);
}

.card-face {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border-radius: var(--radius-xl);
  padding: 40px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  background: var(--bg-card);
  backdrop-filter: blur(20px);
  border: 1px solid var(--glass-border);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.5);
}

.card-front {
  background: linear-gradient(135deg, rgba(30, 41, 59, 0.9), rgba(15, 23, 42, 0.9));
}

.card-back {
  transform: rotateY(180deg);
  background: linear-gradient(135deg, rgba(15, 23, 42, 0.95), rgba(30, 41, 59, 0.95));
}

.card-word {
  font-size: 2.8rem;
  font-weight: 800;
  margin: 16px 0;
  background: linear-gradient(to right, #fff, #cbd5e1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.btn-speech {
  background: rgba(99, 102, 241, 0.2);
  border: 1px solid rgba(99, 102, 241, 0.4);
  color: var(--accent-primary);
  width: 44px;
  height: 44px;
  border-radius: 50%;
  font-size: 1.1rem;
  cursor: pointer;
  transition: var(--transition-fast);
}

.btn-speech:hover {
  transform: scale(1.1);
  background: var(--accent-primary);
  color: #fff;
}

.hint-text {
  font-size: 0.8rem;
  color: var(--text-dim);
  margin-top: auto;
}

.fc-action-buttons {
  display: flex;
  justify-content: center;
  gap: 16px;
}

.btn-fc {
  padding: 14px 28px;
  border-radius: var(--radius-lg);
  font-size: 1rem;
}

.btn-repeat { background: rgba(244, 63, 94, 0.15); color: var(--accent-danger); border: 1px solid rgba(244, 63, 94, 0.3); }
.btn-good { background: rgba(16, 185, 129, 0.2); color: var(--accent-success); border: 1px solid rgba(16, 185, 129, 0.4); }
.btn-star { background: rgba(245, 158, 11, 0.15); color: var(--accent-warning); border: 1px solid rgba(245, 158, 11, 0.3); }

/* Quiz Styling */
.quiz-setup {
  max-width: 600px;
  margin: 40px auto;
  padding: 40px;
  text-align: center;
}

.quiz-icon-hero {
  font-size: 3rem;
  color: var(--accent-primary);
  margin-bottom: 16px;
}

.quiz-options {
  margin: 30px 0;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.quiz-active {
  max-width: 700px;
  margin: 20px auto;
  padding: 32px;
}

.quiz-header {
  display: flex;
  justify-content: space-between;
  margin-bottom: 24px;
}

.quiz-choices-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 24px;
}

.choice-btn {
  padding: 18px 24px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  color: var(--text-main);
  font-size: 1rem;
  cursor: pointer;
  text-align: left;
  transition: var(--transition-fast);
}

.choice-btn:hover {
  background: rgba(99, 102, 241, 0.2);
  border-color: var(--accent-primary);
}

.choice-btn.correct { background: rgba(16, 185, 129, 0.3) !important; border-color: var(--accent-success) !important; }
.choice-btn.incorrect { background: rgba(244, 63, 94, 0.3) !important; border-color: var(--accent-danger) !important; }

/* Modal Box */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
}

.modal-box {
  width: 90%;
  max-width: 520px;
  padding: 32px;
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.close-modal-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 1.6rem;
  cursor: pointer;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 16px;
}

.form-group input, .form-group textarea {
  background: rgba(0, 0, 0, 0.3);
  border: 1px solid var(--glass-border);
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  color: var(--text-main);
  outline: none;
}

/* Responsive Styles for Mobile & Tablets */
@media (max-width: 768px) {
  .app-container {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
    height: auto;
    position: relative;
    padding: 16px 12px;
    gap: 12px;
    border-right: none;
    border-bottom: 1px solid var(--glass-border);
  }

  .nav-menu {
    display: flex;
    flex-direction: row;
    overflow-x: auto;
    scroll-behavior: smooth;
    -webkit-overflow-scrolling: touch;
    gap: 8px;
    padding-bottom: 8px;
    width: 100%;
  }

  .nav-item {
    flex-shrink: 0;
    white-space: nowrap;
    padding: 10px 14px;
    font-size: 0.85rem;
    border-left: none !important;
    border-bottom: 3px solid transparent;
  }

  .nav-item.active {
    border-bottom: 3px solid var(--accent-primary) !important;
    background: rgba(99, 102, 241, 0.2);
  }

  .main-content {
    padding: 16px 12px;
    gap: 20px;
    width: 100%;
  }

  .top-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .header-right {
    width: 100%;
    display: flex;
    gap: 8px;
  }

  .header-right .btn {
    flex: 1;
    justify-content: center;
    padding: 10px 12px;
    font-size: 0.85rem;
  }

  .word-grid {
    grid-template-columns: 1fr !important;
    gap: 16px;
  }

  .dashboard-widgets {
    grid-template-columns: 1fr;
  }

  .filter-bar {
    flex-direction: column;
    align-items: stretch;
    padding: 12px;
  }

  .filter-group {
    flex-direction: column;
    width: 100%;
  }

  .custom-select {
    width: 100%;
  }

  .flashcard-container {
    height: 380px;
    padding: 0;
  }

  .card-face {
    padding: 20px 16px;
  }

  .card-word {
    font-size: 2rem;
  }

  .quiz-choices-container {
    grid-template-columns: 1fr;
  }

  .fc-action-buttons {
    flex-direction: column;
    gap: 10px;
  }

  .btn-fc {
    width: 100%;
    justify-content: center;
  }
}

.hidden { display: none !important; }