/* ==========================================================================
   ATPL CBT - Main OLED Dark Cockpit Styling
   ========================================================================== */

:root {
  --bg-primary: #050811;
  --bg-card: #090d16;
  --bg-surface: #0f172a;
  --bg-elevated: #1e293b;
  --bg-hover: #334155;

  --border-subtle: #1e293b;
  --border-strong: #334155;
  --border-accent: #0284c7;

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --text-inverted: #050811;

  --accent-cyan: #38bdf8;
  --accent-blue: #0284c7;
  --accent-green: #10b981;
  --accent-red: #ef4444;
  --accent-amber: #f59e0b;
  --accent-purple: #a855f7;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.6);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.8);
  --glow-cyan: 0 0 16px rgba(56, 189, 248, 0.25);
  --glow-green: 0 0 16px rgba(16, 185, 129, 0.25);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  user-select: none;
}

/* 共通スクロールバー */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}
::-webkit-scrollbar-track {
  background: var(--bg-primary);
}
::-webkit-scrollbar-thumb {
  background: var(--border-strong);
  border-radius: var(--radius-full);
}
::-webkit-scrollbar-thumb:hover {
  background: var(--accent-cyan);
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */

.app-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(9, 13, 22, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
  padding: 0.6rem 1.2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  cursor: pointer;
  text-decoration: none;
}

.brand-icon {
  width: 34px;
  height: 34px;
  border-radius: var(--radius-sm);
  display: block;
}

.brand-title {
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: 0.5px;
  color: var(--text-primary);
  display: flex;
  align-items: baseline;
  gap: 0.4rem;
}

.brand-badge {
  font-size: 0.65rem;
  font-weight: 700;
  padding: 2px 6px;
  border-radius: var(--radius-full);
  background-color: rgba(16, 185, 129, 0.15);
  color: var(--accent-green);
  border: 1px solid rgba(16, 185, 129, 0.3);
  letter-spacing: 0.5px;
}

/* Nav Tabs */
.nav-tabs {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  background-color: var(--bg-surface);
  padding: 0.25rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-subtle);
  overflow-x: auto;
}

.nav-tab-btn {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  font-size: 0.85rem;
  font-weight: 600;
  padding: 0.45rem 0.9rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  transition: all 0.2s ease;
  white-space: nowrap;
}

.nav-tab-btn:hover {
  color: var(--text-primary);
  background-color: rgba(255, 255, 255, 0.05);
}

.nav-tab-btn.active {
  background-color: var(--accent-blue);
  color: #ffffff;
  box-shadow: 0 0 10px rgba(2, 132, 199, 0.4);
}

.nav-tab-btn .badge-pill {
  background: rgba(0, 0, 0, 0.3);
  font-size: 0.7rem;
  padding: 1px 6px;
  border-radius: var(--radius-full);
}

/* Header Right */
.header-actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.offline-indicator {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.3rem 0.6rem;
  border-radius: var(--radius-full);
  background-color: rgba(16, 185, 129, 0.1);
  color: var(--accent-green);
  border: 1px solid rgba(16, 185, 129, 0.25);
}

.indicator-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--accent-green);
  box-shadow: 0 0 6px var(--accent-green);
}

.btn-icon {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.2s;
}

.btn-icon:hover {
  color: var(--text-primary);
  border-color: var(--border-strong);
  background-color: var(--bg-elevated);
}

/* ==========================================================================
   Main Container & Section Views
   ========================================================================== */

.app-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  position: relative;
  max-width: 1400px;
  width: 100%;
  margin: 0 auto;
  padding: 1rem;
}

.view-section {
  display: none;
  flex-direction: column;
  flex: 1;
  animation: fadeIn 0.2s ease-out;
}

.view-section.active {
  display: flex;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Filter & Subject Selection Bar */
.filter-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 0.6rem 0.9rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.subject-pills {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  overflow-x: auto;
  max-width: 100%;
  padding-bottom: 2px;
}

.pill-btn {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  cursor: pointer;
  white-space: nowrap;
  transition: all 0.15s ease;
}

.pill-btn:hover {
  background-color: var(--bg-elevated);
  color: var(--text-primary);
}

.pill-btn.active {
  background-color: var(--accent-cyan);
  color: var(--text-inverted);
  border-color: var(--accent-cyan);
  font-weight: 700;
  box-shadow: var(--glow-cyan);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.6rem 1.2rem;
  border-radius: var(--radius-md);
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.18s ease;
  user-select: none;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background: linear-gradient(135deg, #0284c7, #0369a1);
  color: #ffffff;
  box-shadow: 0 4px 12px rgba(2, 132, 199, 0.3);
}
.btn-primary:hover {
  background: linear-gradient(135deg, #0ea5e9, #0284c7);
  box-shadow: 0 4px 16px rgba(2, 132, 199, 0.5);
}

.btn-secondary {
  background-color: var(--bg-surface);
  border-color: var(--border-strong);
  color: var(--text-primary);
}
.btn-secondary:hover {
  background-color: var(--bg-elevated);
  border-color: var(--accent-cyan);
}

.btn-success {
  background: linear-gradient(135deg, #10b981, #059669);
  color: #ffffff;
  box-shadow: 0 4px 12px rgba(16, 185, 129, 0.3);
}
.btn-success:hover {
  background: linear-gradient(135deg, #34d399, #10b981);
}

.btn-danger {
  background: linear-gradient(135deg, #ef4444, #dc2626);
  color: #ffffff;
}
.btn-danger:hover {
  background: linear-gradient(135deg, #f87171, #ef4444);
}

/* ==========================================================================
   Question Card Standard Layout (Used across Practice & Exam)
   ========================================================================== */

.question-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  position: relative;
}

.question-meta-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: 0.75rem;
}

.meta-tags {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.tag-subject {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: var(--radius-sm);
  background-color: rgba(56, 189, 248, 0.15);
  color: var(--accent-cyan);
  border: 1px solid rgba(56, 189, 248, 0.3);
}

.tag-source {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 3px 8px;
  border-radius: var(--radius-sm);
  background-color: var(--bg-surface);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
  font-family: var(--font-mono);
}

.btn-flag {
  background: transparent;
  border: 1px solid var(--border-subtle);
  color: var(--text-muted);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.4rem 0.8rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  transition: all 0.2s;
}

.btn-flag:hover {
  color: var(--accent-amber);
  border-color: var(--accent-amber);
}

.btn-flag.active {
  background-color: rgba(245, 158, 11, 0.15);
  color: var(--accent-amber);
  border-color: var(--accent-amber);
}

.question-text {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.7;
  white-space: pre-wrap;
  user-select: text;
}

/* Options List */
.options-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.option-btn {
  background-color: var(--bg-surface);
  border: 1.5px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 0.9rem 1.1rem;
  color: var(--text-primary);
  font-size: 0.95rem;
  line-height: 1.5;
  text-align: left;
  cursor: pointer;
  display: flex;
  align-items: flex-start;
  gap: 0.85rem;
  transition: all 0.15s ease;
  user-select: text;
}

.option-btn:hover {
  background-color: var(--bg-elevated);
  border-color: var(--border-strong);
}

.opt-badge {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 800;
  width: 28px;
  height: 28px;
  min-width: 28px;
  border-radius: var(--radius-sm);
  background-color: var(--bg-elevated);
  border: 1px solid var(--border-strong);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s ease;
  user-select: none;
}

.opt-content {
  flex: 1;
  word-break: break-word;
}

/* 選択・正誤判定スタイル */
.option-btn.selected {
  border-color: var(--accent-cyan);
  background-color: rgba(56, 189, 248, 0.1);
}
.option-btn.selected .opt-badge {
  background-color: var(--accent-cyan);
  color: var(--text-inverted);
  border-color: var(--accent-cyan);
}

.option-btn.correct {
  border-color: var(--accent-green) !important;
  background-color: rgba(16, 185, 129, 0.15) !important;
  box-shadow: 0 0 12px rgba(16, 185, 129, 0.2);
}
.option-btn.correct .opt-badge {
  background-color: var(--accent-green) !important;
  color: #ffffff !important;
  border-color: var(--accent-green) !important;
}

.option-btn.incorrect {
  border-color: var(--accent-red) !important;
  background-color: rgba(239, 68, 68, 0.15) !important;
}
.option-btn.incorrect .opt-badge {
  background-color: var(--accent-red) !important;
  color: #ffffff !important;
  border-color: var(--accent-red) !important;
}

/* Explanation & Reference Box */
.explanation-box {
  margin-top: 0.5rem;
  padding: 1.25rem;
  border-radius: var(--radius-md);
  background-color: rgba(15, 23, 42, 0.85);
  border: 1px solid var(--border-strong);
  border-left: 4px solid var(--accent-cyan);
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  animation: fadeIn 0.25s ease;
  user-select: text;
}

.exp-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  font-weight: 800;
  color: var(--accent-cyan);
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

.exp-body {
  font-size: 0.95rem;
  color: var(--text-primary);
  line-height: 1.65;
  white-space: pre-wrap;
}

.ref-section {
  padding-top: 0.75rem;
  border-top: 1px dashed var(--border-subtle);
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.ref-title {
  font-weight: 700;
  color: var(--accent-amber);
  margin-bottom: 0.3rem;
}

/* ==========================================================================
   Modal Dialogs
   ========================================================================== */

.modal-backdrop {
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.8);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: 1000;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
}

.modal-backdrop.active {
  display: flex;
}

.modal-dialog {
  background-color: var(--bg-card);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  max-width: 580px;
  width: 100%;
  padding: 1.75rem;
  box-shadow: var(--shadow-lg);
  position: relative;
  animation: scaleIn 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

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

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.25rem;
}

.modal-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-primary);
}

.modal-close {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 1.4rem;
  cursor: pointer;
  line-height: 1;
}
.modal-close:hover {
  color: var(--text-primary);
}

/* Responsive Breakpoints & Mobile Optimization */
@media (max-width: 768px) {
  /* 全体の余白と横スクロール完全防止 */
  html, body {
    overflow-x: hidden;
    width: 100%;
    max-width: 100vw;
  }

  body {
    min-height: 100dvh;
  }

  /* ログイン画面のスマホ最適化 */
  #auth-overlay {
    padding: 1rem !important;
  }
  #auth-overlay > div {
    padding: 1.75rem 1.2rem !important;
  }

  /* Compact Header */
  .app-header {
    padding: 0.4rem 0.65rem;
    flex-wrap: nowrap;
    gap: 0.5rem;
  }

  .brand {
    gap: 0.5rem;
    flex-shrink: 0;
  }

  .brand-icon {
    width: 26px;
    height: 26px;
  }

  .brand-title {
    font-size: 0.95rem;
  }

  .brand-badge {
    display: none; /* スマホでは省略してスッキリ */
  }

  .header-actions {
    gap: 0.35rem;
    flex-shrink: 0;
    margin-left: auto;
  }

  .offline-indicator {
    padding: 0.2rem 0.45rem;
    font-size: 0.68rem;
  }

  #user-display-email {
    display: none; /* スマホではメールアドレステキストを隠してアイコンだけにする */
  }

  #user-profile-badge {
    padding: 0.2rem 0.4rem !important;
  }

  /* Bottom Navigation Bar (モバイル特化ボトムナビ) */
  .nav-tabs {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 990;
    background: rgba(9, 13, 22, 0.96);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-top: 1px solid var(--border-subtle);
    border-radius: 0;
    border-left: none;
    border-right: none;
    border-bottom: none;
    margin: 0;
    padding: 0.35rem 0.2rem calc(0.35rem + env(safe-area-inset-bottom, 0px));
    display: flex;
    justify-content: space-around;
    gap: 0;
    box-shadow: 0 -4px 16px rgba(0, 0, 0, 0.5);
  }

  .nav-tab-btn {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 0.15rem;
    padding: 0.3rem 0.1rem;
    font-size: 0.65rem;
    border-radius: var(--radius-sm);
    min-width: 0;
  }

  .nav-tab-btn span {
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  /* Main Container (ボトムナビ分の下部余白を確保し、画面を100%フル活用) */
  .app-main {
    padding: 0.4rem 0.5rem calc(68px + env(safe-area-inset-bottom, 0px)) 0.5rem;
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
  }

  /* Filter Bar Compact */
  .filter-bar {
    padding: 0.35rem 0.5rem;
    margin-bottom: 0.5rem;
    gap: 0.35rem;
    border-radius: var(--radius-sm);
    flex-wrap: nowrap !important;
    overflow-x: auto !important;
    -webkit-overflow-scrolling: touch;
  }

  .filter-bar > div {
    flex-shrink: 0;
  }

  .desktop-shortcut-guide {
    display: none !important;
  }

  .pill-btn {
    padding: 0.25rem 0.55rem;
    font-size: 0.72rem;
  }

  /* Question Card Compact (スクロールなしで1画面に収める) */
  .question-card {
    padding: 0.75rem 0.85rem;
    gap: 0.65rem;
    border-radius: var(--radius-md);
  }

  .question-meta-row {
    padding-bottom: 0.45rem;
    gap: 0.5rem;
  }

  .tag-subject, .tag-source {
    font-size: 0.68rem;
    padding: 2px 6px;
  }

  .btn-flag {
    padding: 0.25rem 0.55rem;
    font-size: 0.72rem;
  }

  .question-text {
    font-size: 0.92rem;
    line-height: 1.5;
  }

  /* Options List Compact */
  .options-list {
    gap: 0.45rem;
  }

  .option-btn {
    padding: 0.5rem 0.7rem;
    font-size: 0.85rem;
    line-height: 1.35;
    gap: 0.6rem;
    border-radius: var(--radius-sm);
  }

  .opt-badge {
    width: 24px;
    height: 24px;
    min-width: 24px;
    font-size: 0.75rem;
  }

  /* Buttons */
  .btn {
    padding: 0.45rem 0.8rem;
    font-size: 0.82rem;
    border-radius: var(--radius-sm);
  }

  .cbt-nav-footer {
    margin-top: 0.4rem;
    gap: 0.5rem;
  }
}