:root {
  color-scheme: light;
  --bg: #f5f7f3;
  --surface: #ffffff;
  --surface-strong: #edf3ea;
  --text: #20241f;
  --muted: #647064;
  --border: #d8dfd4;
  --accent: #1f7a5c;
  --accent-strong: #165f49;
  --danger: #a64035;
  --amber: #b46d18;
  --shadow: 0 12px 36px rgba(32, 46, 34, 0.08);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Microsoft YaHei", "PingFang SC", "Noto Sans SC", Arial, sans-serif;
  line-height: 1.5;
}

button,
input,
select {
  font: inherit;
}

.app {
  min-height: 100vh;
  padding: 24px;
}

.topbar,
.stats,
.study-layout {
  margin-left: auto;
  margin-right: auto;
  max-width: 1180px;
}

.topbar {
  align-items: center;
  display: flex;
  gap: 16px;
  justify-content: space-between;
  margin-bottom: 18px;
}

h1,
h2,
p {
  margin-top: 0;
}

h1 {
  font-size: 28px;
  letter-spacing: 0;
  margin-bottom: 4px;
}

.topbar p {
  color: var(--muted);
  margin-bottom: 0;
}

.top-actions {
  align-items: center;
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.token-input,
.goal-control input {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  min-height: 40px;
  padding: 0 10px;
}

.token-input {
  width: 150px;
}

.goal-control {
  align-items: center;
  color: var(--muted);
  display: flex;
  font-size: 13px;
  gap: 6px;
}

.goal-control input {
  width: 76px;
}

.primary-action,
.secondary-action,
.danger-action,
.rating {
  border-radius: 6px;
  cursor: pointer;
  min-height: 40px;
  padding: 0 16px;
}

button:disabled {
  cursor: wait;
  opacity: 0.58;
}

.primary-action {
  background: var(--accent);
  border: 1px solid var(--accent);
  color: #fff;
}

.primary-action:hover {
  background: var(--accent-strong);
}

.secondary-action {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
}

.danger-action {
  background: #fff5f3;
  border: 1px solid #e7c4bd;
  color: var(--danger);
}

.stats {
  display: grid;
  gap: 10px;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  margin-bottom: 14px;
}

.stats div {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px 14px;
}

.stats span {
  display: block;
  font-size: 26px;
  font-weight: 700;
}

.stats label {
  color: var(--muted);
  display: block;
  font-size: 13px;
}

.study-layout {
  display: grid;
  gap: 14px;
  grid-template-columns: minmax(360px, 1fr);
  max-width: 900px;
}

.study-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.study-panel {
  min-height: 560px;
  position: relative;
}

.study-card {
  display: flex;
  flex-direction: column;
  gap: 18px;
  min-height: 560px;
  padding: 28px;
}

.save-status {
  color: var(--muted);
  font-size: 13px;
  padding: 14px 18px 0;
  text-align: right;
}

.card-meta {
  color: var(--muted);
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  font-size: 13px;
}

.card-meta span {
  background: var(--surface-strong);
  border-radius: 999px;
  padding: 4px 9px;
}

.front {
  align-items: center;
  display: flex;
  flex: 1;
  font-size: 34px;
  font-weight: 700;
  justify-content: center;
  letter-spacing: 0;
  line-height: 1.45;
  min-height: 220px;
  text-align: center;
}

.reveal-action {
  align-self: center;
  min-width: 140px;
}

.answer-block,
.score-gain,
.review-error {
  border-top: 1px solid var(--border);
  padding-top: 14px;
}

.answer-block span,
.score-gain span {
  color: var(--muted);
  display: block;
  font-size: 13px;
  margin-bottom: 6px;
}

.answer-block p {
  background: #fff9ed;
  border-left: 3px solid var(--amber);
  font-size: 20px;
  margin: 0;
  padding: 12px 14px;
}

.score-gain p {
  color: var(--muted);
  margin-bottom: 0;
}

.review-error {
  color: var(--danger);
  display: flex;
  gap: 10px;
  justify-content: space-between;
}

.review-error p {
  margin: 0;
}

.ratings {
  display: grid;
  gap: 10px;
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.rating {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
}

.rating.again {
  border-color: #e0b4ae;
  color: var(--danger);
}

.rating.hard {
  border-color: #e0c49b;
  color: #80500d;
}

.rating.good,
.rating.easy {
  border-color: #acd3c3;
  color: var(--accent-strong);
}

.done-state,
.empty-state,
.error-state {
  color: var(--muted);
  padding: 18px;
}

.done-state {
  margin: auto;
  max-width: 460px;
  text-align: center;
}

.done-state h2 {
  color: var(--text);
  font-size: 24px;
  letter-spacing: 0;
}

.done-stats {
  display: grid;
  gap: 10px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: 18px 0 0;
}

.done-stats div {
  background: var(--surface-strong);
  border-radius: 8px;
  padding: 10px;
}

.done-stats dt {
  color: var(--muted);
  font-size: 13px;
}

.done-stats dd {
  color: var(--text);
  font-size: 24px;
  font-weight: 700;
  margin: 2px 0 0;
}

.error-state {
  color: var(--danger);
  white-space: pre-wrap;
}

.overview-panel[hidden] {
  display: none;
}

.overview-panel {
  align-items: center;
  background: rgba(32, 36, 31, 0.34);
  display: flex;
  inset: 0;
  justify-content: center;
  padding: 24px;
  position: fixed;
  z-index: 20;
}

.overview-shell {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  max-height: calc(100vh - 48px);
  max-width: 1120px;
  overflow: hidden;
  width: 100%;
}

.overview-header {
  align-items: center;
  border-bottom: 1px solid var(--border);
  display: flex;
  gap: 16px;
  justify-content: space-between;
  padding: 18px 20px;
}

.overview-header h2 {
  font-size: 22px;
  letter-spacing: 0;
  margin-bottom: 2px;
}

.overview-header p {
  color: var(--muted);
  font-size: 13px;
  margin-bottom: 0;
}

.overview-filters {
  border-bottom: 1px solid var(--border);
  display: grid;
  gap: 10px;
  grid-template-columns: minmax(220px, 1fr) minmax(140px, 180px) minmax(140px, 180px);
  padding: 14px 20px;
}

.overview-filters input,
.overview-filters select {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  min-height: 40px;
  min-width: 0;
  padding: 0 10px;
}

.overview-list {
  display: grid;
  gap: 10px;
  overflow: auto;
  padding: 14px 20px 20px;
}

.overview-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
}

.overview-item h3 {
  font-size: 18px;
  letter-spacing: 0;
  line-height: 1.45;
  margin: 10px 0;
  overflow-wrap: anywhere;
}

.overview-item p {
  color: var(--muted);
  margin-bottom: 8px;
  overflow-wrap: anywhere;
}

.overview-item p strong {
  color: var(--text);
}

.overview-source {
  font-size: 13px;
}

.overview-item-head {
  align-items: center;
  color: var(--muted);
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  font-size: 13px;
}

.overview-item-head span:not(.status-pill) {
  background: var(--surface-strong);
  border-radius: 999px;
  padding: 4px 9px;
}

.status-pill {
  border: 1px solid var(--border);
  border-radius: 999px;
  font-weight: 700;
  padding: 4px 9px;
}

.status-pill.new {
  background: #f3f4f1;
  color: var(--muted);
}

.status-pill.due {
  background: #fff5f3;
  border-color: #e7c4bd;
  color: var(--danger);
}

.status-pill.scheduled {
  background: #edf8f3;
  border-color: #acd3c3;
  color: var(--accent-strong);
}

.overview-progress {
  border-top: 1px solid var(--border);
  color: var(--muted);
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: space-between;
  margin-top: 10px;
  padding-top: 10px;
}

@media (max-width: 860px) {
  .app {
    padding: 16px;
  }

  .topbar,
  .top-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .topbar {
    align-items: stretch;
  }

  .token-input {
    min-width: 0;
    width: 100%;
  }

  .stats {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .ratings {
    grid-template-columns: 1fr;
  }

  .front {
    font-size: 26px;
  }

  .overview-panel {
    align-items: stretch;
    padding: 0;
  }

  .overview-shell {
    border-radius: 0;
    max-height: 100vh;
  }

  .overview-header {
    align-items: stretch;
    flex-direction: column;
    padding: 16px;
  }

  .overview-filters {
    grid-template-columns: 1fr;
    padding: 12px 16px;
  }

  .overview-list {
    padding: 12px 16px 16px;
  }

  .overview-progress {
    flex-direction: column;
  }
}