/* ============================================
 * 韓文學習網站共用樣式
 * 設計原則：手機/桌面通用、夜間友善、無框架依賴
 * ============================================ */

:root {
  --bg: #0e1117;
  --surface: #161b22;
  --surface-2: #1f2530;
  --border: #2d333b;
  --text: #e6edf3;
  --text-dim: #8b949e;
  --accent: #4d9eff;
  --accent-hover: #6cb0ff;
  --success: #3fb950;
  --warning: #d29922;
  --danger: #f85149;
  --radius: 10px;
  --max-width: 960px;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f6f8fa;
    --surface: #ffffff;
    --surface-2: #eef1f4;
    --border: #d0d7de;
    --text: #1f2328;
    --text-dim: #57606a;
    --accent: #0969da;
    --accent-hover: #1f6feb;
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Apple SD Gothic Neo",
    "Noto Sans TC", "Noto Sans KR", "PingFang TC", "Microsoft JhengHei", sans-serif;
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-hover); text-decoration: underline; }

/* ---------- Layout ---------- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 16px;
}

header.app-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 12px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  position: sticky;
  top: 0;
  z-index: 10;
}

header.app-header .logo {
  font-weight: 700;
  font-size: 18px;
}

header.app-header nav {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

header.app-header nav a {
  color: var(--text-dim);
  font-size: 14px;
  padding: 4px 8px;
  border-radius: 6px;
}

header.app-header nav a:hover {
  background: var(--surface-2);
  text-decoration: none;
}

header.app-header .user-info {
  font-size: 13px;
  color: var(--text-dim);
  display: flex;
  align-items: center;
  gap: 8px;
}

footer {
  margin-top: 48px;
  padding: 20px 16px;
  text-align: center;
  color: var(--text-dim);
  font-size: 13px;
}

/* ---------- Cards ---------- */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
}

.card h2, .card h3 {
  margin-top: 0;
}

.grid {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 18px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--surface-2);
  color: var(--text);
  font-size: 15px;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s;
  text-decoration: none;
}

.btn:hover { background: var(--surface); }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.btn-primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); }

.btn-success { background: var(--success); border-color: var(--success); color: #fff; }
.btn-warning { background: var(--warning); border-color: var(--warning); color: #1f1f1f; }
.btn-danger  { background: var(--danger);  border-color: var(--danger);  color: #fff; }

.btn-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 12px;
}

/* ---------- Forms ---------- */
.form-group {
  margin-bottom: 16px;
}
.form-group label {
  display: block;
  margin-bottom: 6px;
  font-size: 14px;
  color: var(--text-dim);
}
.form-group input {
  width: 100%;
  padding: 10px 12px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-size: 15px;
}
.form-group input:focus {
  outline: none;
  border-color: var(--accent);
}

.form-error {
  color: var(--danger);
  font-size: 14px;
  margin-top: 8px;
  min-height: 20px;
}

/* ---------- Stats / Pills ---------- */
.stat {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 12px 16px;
  background: var(--surface-2);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}
.stat .label { font-size: 12px; color: var(--text-dim); }
.stat .value { font-size: 24px; font-weight: 700; }

.pill {
  display: inline-block;
  padding: 2px 8px;
  font-size: 12px;
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--text-dim);
  border: 1px solid var(--border);
}

.pill-due { background: rgba(248,81,73,.15); color: var(--danger); border-color: rgba(248,81,73,.3); }
.pill-ok  { background: rgba(63,185,80,.15);  color: var(--success); border-color: rgba(63,185,80,.3); }

/* ---------- Alphabet grid ---------- */
.alphabet-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(96px, 1fr));
  gap: 12px;
}

.alphabet-cell {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 8px;
  text-align: center;
  cursor: pointer;
  user-select: none;
  transition: transform 0.1s, border-color 0.15s;
}
.alphabet-cell:hover { border-color: var(--accent); }
.alphabet-cell:active { transform: scale(0.97); }
.alphabet-cell.learned { background: rgba(63,185,80,.08); border-color: rgba(63,185,80,.4); }

.alphabet-cell .char { font-size: 36px; font-weight: 700; }
.alphabet-cell .romanization { font-size: 13px; color: var(--text-dim); margin-top: 4px; }

.alphabet-detail {
  display: none;
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 16px;
  margin-top: 12px;
}
.alphabet-detail.show { display: block; }

/* ---------- Flashcard ---------- */
.flashcard {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px 20px;
  text-align: center;
  min-height: 260px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  user-select: none;
}
.flashcard .ko { font-size: 48px; font-weight: 700; }
.flashcard .ro { font-size: 18px; color: var(--text-dim); margin-top: 8px; }
.flashcard .zh { font-size: 22px; margin-top: 16px; }
.flashcard .example { font-size: 15px; color: var(--text-dim); margin-top: 12px; }
.flashcard .hint { font-size: 13px; color: var(--text-dim); margin-top: 24px; }

/* ---------- Quiz ---------- */
.quiz-question {
  font-size: 22px;
  margin-bottom: 20px;
  text-align: center;
}
.quiz-options {
  display: grid;
  gap: 10px;
}
.quiz-option {
  text-align: left;
  padding: 14px 16px;
  font-size: 16px;
}
.quiz-option.correct { background: rgba(63,185,80,.2); border-color: var(--success); }
.quiz-option.wrong   { background: rgba(248,81,73,.2); border-color: var(--danger); }

/* ---------- Utility ---------- */
.text-dim { color: var(--text-dim); }
.text-center { text-align: center; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mb-2 { margin-bottom: 16px; }
.flex { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.spacer { flex: 1; }
.hidden { display: none !important; }

/* ---------- Loading ---------- */
.loading {
  text-align: center;
  padding: 40px;
  color: var(--text-dim);
}

/* ---------- Toast ---------- */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 10px 16px;
  font-size: 14px;
  z-index: 100;
  box-shadow: 0 4px 16px rgba(0,0,0,.3);
}
.toast.error { border-color: var(--danger); }
.toast.success { border-color: var(--success); }

/* ---------- 首頁模組入口卡 ---------- */
.module-card {
  flex-direction: column;
  padding: 24px;
  font-size: 18px;
  font-weight: 600;
  text-align: center;
  gap: 6px;
  transition: transform 0.15s, border-color 0.15s, background 0.15s;
}
.module-card .text-dim {
  font-size: 13px;
  font-weight: normal;
}
.module-card:hover {
  border-color: var(--accent);
  background: var(--surface);
  transform: translateY(-2px);
  text-decoration: none;
}
.module-card:active {
  transform: translateY(0);
}

/* ---------- Version badge ---------- */
.version-badge {
  position: fixed;
  right: 12px;
  bottom: 12px;
  padding: 4px 10px;
  font-size: 11px;
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Consolas, monospace;
  color: var(--text-dim);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  z-index: 50;
  text-decoration: none;
  opacity: 0.65;
  transition: opacity 0.15s;
}
.version-badge:hover {
  opacity: 1;
  text-decoration: none;
  color: var(--accent);
}

@media (max-width: 600px) {
  header.app-header { flex-direction: column; align-items: flex-start; }
  .flashcard .ko { font-size: 38px; }
  .flashcard { padding: 28px 16px; min-height: 220px; }
}