:root {
  --bg: #f5f6f8;
  --card: #ffffff;
  --text: #1a1a1a;
  --muted: #7a8088;
  --primary: #2b6cb0;
  --primary-dark: #1f4e7a;
  --border: #e3e6ea;
  --today-bg: #ebf4ff;
  --locked-bg: #f2f3f5;
  --success: #2f855a;
  --danger: #c53030;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

header {
  padding: 18px 16px;
  background: var(--card);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}

header h1 { margin: 0; font-size: 21px; }
.today { margin: 0; color: var(--muted); font-size: 14px; }

.admin-link {
  color: var(--muted);
  text-decoration: none;
  font-size: 13px;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px 12px;
}
.admin-link:hover { color: var(--primary); border-color: var(--primary); }

.layout {
  display: flex;
  max-width: 900px;
  margin: 0 auto;
  padding: 16px;
  gap: 16px;
  align-items: flex-start;
}
.sidebar {
  width: 170px;
  flex-shrink: 0;
  position: sticky;
  top: 80px;
}
.sidebar-btn { width: 100%; margin-bottom: 8px; }
.week-nav { display: flex; flex-direction: column; gap: 2px; margin-top: 8px; }
.week-nav-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 10px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 13px;
  color: var(--text);
}
.week-nav-item:hover { background: #f0f4f8; }
.week-nav-item.active { background: var(--primary); color: #fff; }
.week-nav-item.current .week-range { font-weight: bold; }
.week-range { white-space: nowrap; }
.week-progress {
  font-size: 12px;
  color: var(--muted);
  background: #eef2f7;
  border-radius: 10px;
  padding: 1px 8px;
}
.week-nav-item.active .week-progress { background: rgba(255, 255, 255, 0.25); color: #fff; }

main { max-width: 640px; margin: 0 auto; padding: 16px; }
.layout main { flex: 1; min-width: 0; max-width: none; margin: 0; padding: 0; }

@media (max-width: 640px) {
  .layout { flex-direction: column; }
  .sidebar { width: 100%; position: static; display: flex; flex-wrap: wrap; gap: 8px; }
  .sidebar-btn { width: auto; margin-bottom: 0; }
  .week-nav { flex-direction: row; flex-wrap: wrap; }
  .week-nav-item { width: auto; }
}

.notice {
  background: #fff8e6;
  border: 1px solid #f0e2b6;
  color: #8a6d1a;
  border-radius: 10px;
  padding: 12px 14px;
  margin-bottom: 12px;
  font-size: 14px;
}

.empty { text-align: center; color: var(--muted); padding: 40px 0; }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 12px;
}
.card.today { border-color: var(--primary); background: var(--today-bg); }
.card.locked { background: var(--locked-bg); opacity: 0.75; }

.card-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 4px;
}
.date { font-size: 13px; color: var(--muted); }
.title { margin: 4px 0 12px; font-size: 18px; }

.badge {
  font-size: 12px;
  border-radius: 6px;
  padding: 2px 8px;
}
.today-badge { background: var(--primary); color: #fff; }
.checked-badge { background: #e6f6ec; color: var(--success); }
.reviewed-badge { background: #eef2f7; color: var(--muted); }

audio { width: 100%; margin-bottom: 12px; }

.checkin-area textarea {
  width: 100%;
  min-height: 64px;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
  font-size: 14px;
  font-family: inherit;
  resize: vertical;
  margin-bottom: 8px;
}
.checkin-area textarea:focus { outline: none; border-color: var(--primary); }

.btn {
  display: inline-block;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 10px 18px;
  font-size: 15px;
  cursor: pointer;
}
.btn:hover { background: var(--primary-dark); }
.btn:disabled { background: #a0b8d0; cursor: not-allowed; }
.btn.secondary { background: #eef2f7; color: var(--text); }
.btn.danger { background: var(--danger); }

.pdf-link {
  display: inline-block;
  margin-top: 8px;
  color: var(--primary);
  text-decoration: none;
  font-size: 14px;
}
.pdf-link:hover { text-decoration: underline; }

.muted { color: var(--muted); font-size: 14px; }

.checkin-row { display: flex; gap: 10px; align-items: center; margin-top: 4px; }
.checkin-row .btn { flex: 1; }
.checkin-row .badge { flex: 1; text-align: center; }
.note-input {
  flex: 1;
  min-height: 44px;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
  font-size: 14px;
  font-family: inherit;
  resize: vertical;
}
.note-input:focus { outline: none; border-color: var(--primary); }
.note-display {
  margin-top: 8px;
  font-size: 14px;
  color: #555;
  background: #f7f9fb;
  border-radius: 8px;
  padding: 8px 12px;
}

.vocab-area { margin-top: 12px; border-top: 1px dashed var(--border); padding-top: 10px; }
.vocab-title { font-size: 14px; margin: 0 0 8px; }
.vocab-item { margin-bottom: 8px; }
.vocab-word {
  display: inline-block;
  font-weight: bold;
  color: var(--primary-dark);
  background: #eef4fb;
  border-radius: 4px;
  padding: 1px 8px;
  margin-right: 8px;
}
.vocab-sentence { font-size: 14px; color: #555; }
.vocab-pos {
  font-size: 11px;
  color: #888;
  margin-left: 4px;
  background: #f0f0f0;
  border-radius: 3px;
  padding: 1px 6px;
}
.edit-word-input {
  flex: 1;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 8px;
  font-size: 14px;
}
.edit-word-input:focus { outline: none; border-color: var(--primary); }
.edit-sentence-input {
  width: 100%;
  margin-top: 6px;
  min-height: 44px;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 8px;
  font-size: 13px;
  font-family: inherit;
  resize: vertical;
}
.edit-sentence-input:focus { outline: none; border-color: var(--primary); }

/* 管理页 */
.lock-screen { max-width: 400px; margin: 40px auto; }
.lock-screen .card { padding: 24px; }
.field { margin-bottom: 14px; }
.field label { display: block; font-size: 14px; margin-bottom: 6px; color: var(--text); }
.field input[type="text"],
.field input[type="password"],
.field input[type="date"] {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
  font-size: 14px;
}
.field input:focus { outline: none; border-color: var(--primary); }

.section-title { font-size: 17px; margin: 24px 0 12px; }

.review-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
}
.review-row:last-child { border-bottom: none; }
.review-info { flex: 1; }
.review-date { font-size: 13px; color: var(--muted); }
.review-title { font-size: 15px; }
.review-summary { font-size: 13px; color: #555; margin-top: 2px; }

.msg { font-size: 13px; margin: 6px 0 0; }
.msg.ok { color: var(--success); }
.msg.err { color: var(--danger); }