:root {
  color-scheme: light;
  --bg: #f3f6ff;
  --card: rgba(255, 255, 255, 0.96);
  --surface: #ffffff;
  --text: #182033;
  --muted: #667085;
  --primary: #4f46e5;
  --primary-soft: #eef2ff;
  --success: #16a34a;
  --danger: #dc2626;
  --border: rgba(79, 70, 229, 0.12);
  --shadow: 0 16px 40px rgba(79, 70, 229, 0.12);
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0f172a;
  --card: rgba(15, 23, 42, 0.92);
  --surface: #111827;
  --text: #e5eefc;
  --muted: #94a3b8;
  --primary: #818cf8;
  --primary-soft: rgba(99, 102, 241, 0.18);
  --success: #4ade80;
  --danger: #f87171;
  --border: rgba(129, 140, 248, 0.22);
  --shadow: 0 16px 40px rgba(2, 6, 23, 0.45);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
}

button,
input,
select,
textarea {
  font: inherit;
}

button {
  border: none;
  cursor: pointer;
}

.app-shell {
  max-width: 760px;
  margin: 0 auto;
  padding: 20px 14px 40px;
}

.hero {
  padding: 28px 20px;
  border-radius: 24px;
  background: linear-gradient(135deg, #4338ca, #6366f1 55%, #818cf8);
  color: #fff;
  box-shadow: var(--shadow);
}

:root[data-theme="dark"] .hero {
  background: linear-gradient(135deg, #312e81, #4338ca 55%, #6366f1);
}

.eyebrow {
  margin: 0 0 8px;
  font-size: 13px;
  opacity: 0.86;
}

.hero h1 {
  margin: 0;
  font-size: 28px;
  line-height: 1.25;
}

.hero-meta {
  margin: 12px 0 0;
  font-size: 14px;
  opacity: 0.92;
}

.page {
  margin-top: 18px;
  display: grid;
  gap: 16px;
}

.ios-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding-top: calc(18px + env(safe-area-inset-top, 0px));
}

.ios-card h2 {
  margin: 0;
  font-size: 18px;
}

.ios-card p {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
}

.ios-badge {
  white-space: nowrap;
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(79, 70, 229, 0.1);
  color: var(--primary);
  font-size: 13px;
  font-weight: 700;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 22px;
  padding: 18px;
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.05);
  backdrop-filter: blur(10px);
}

.controls-header,
.paper-topbar,
.result-header {
  display: flex;
  gap: 12px;
  justify-content: space-between;
  align-items: center;
}

.controls-header h2,
.paper-topbar h2,
.result-header h2 {
  margin: 0;
  font-size: 20px;
}

.controls-header p,
.paper-topbar p,
.result-header p {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.grid.two-cols {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: 16px;
}

.field {
  display: grid;
  gap: 8px;
  color: var(--muted);
  font-size: 14px;
}

.field-full {
  grid-column: 1 / -1;
}

.field input,
.field select,
.inline-select,
.fill-blank-input,
textarea {
  width: 100%;
  border: 1px solid rgba(148, 163, 184, 0.35);
  background: var(--surface);
  border-radius: 14px;
  padding: 12px 14px;
  color: var(--text);
  outline: none;
}

.field input:focus,
.field select:focus,
.inline-select:focus,
.fill-blank-input:focus,
textarea:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}

.actions-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 16px;
}

.primary-btn,
.secondary-btn,
.upload-btn {
  min-height: 44px;
  padding: 0 18px;
  border-radius: 14px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
}

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

.secondary-btn,
.upload-btn {
  background: var(--primary-soft);
  color: var(--primary);
}

.type-stats,
.result-stats,
.live-stats,
.question-nav,
.paper-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 16px;
}

.stat-chip {
  padding: 10px 12px;
  border-radius: 999px;
  background: color-mix(in srgb, var(--surface) 92%, var(--bg));
  color: var(--muted);
  font-size: 13px;
  border: 1px solid rgba(148, 163, 184, 0.2);
}

.nav-chip {
  min-width: 38px;
  height: 38px;
  border-radius: 999px;
  border: 1px solid rgba(148, 163, 184, 0.2);
  background: var(--surface);
  color: var(--muted);
}

.nav-chip.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

.nav-chip.answered {
  border-color: rgba(22, 163, 74, 0.35);
  color: #166534;
}

.nav-chip.active.answered {
  color: #fff;
}

.question-list {
  display: grid;
  gap: 14px;
  margin-top: 18px;
}

.question-card {
  border: 1px solid rgba(148, 163, 184, 0.22);
  border-radius: 18px;
  padding: 16px;
  background: var(--surface);
}

.question-card-tools {
  display: flex;
  justify-content: flex-end;
}

.favorite-btn {
  min-height: 34px;
  padding: 0 12px;
  border-radius: 999px;
  background: rgba(251, 191, 36, 0.14);
  color: #92400e;
}

.active-question {
  border-color: rgba(79, 70, 229, 0.35);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.08);
}

.question-card:has(.result-box.correct) {
  border-color: rgba(22, 163, 74, 0.3);
  box-shadow: inset 0 0 0 1px rgba(22, 163, 74, 0.08);
}

.question-card:has(.result-box.wrong) {
  border-color: rgba(220, 38, 38, 0.3);
  box-shadow: inset 0 0 0 1px rgba(220, 38, 38, 0.08);
}

.question-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 10px;
}

.question-index {
  min-width: 32px;
  height: 32px;
  border-radius: 999px;
  background: var(--primary-soft);
  color: var(--primary);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}

.question-type {
  padding: 6px 10px;
  border-radius: 999px;
  background: color-mix(in srgb, var(--surface) 88%, var(--bg));
  color: var(--muted);
  font-size: 12px;
}

.compact-toolbar {
  margin-top: 0;
}

.inline-select {
  min-height: 44px;
  min-width: 150px;
  border: 1px solid rgba(148, 163, 184, 0.35);
  background: var(--surface);
  border-radius: 14px;
  padding: 0 14px;
  color: var(--text);
}

.inline-input {
  min-height: 44px;
  min-width: 150px;
  border: 1px solid rgba(148, 163, 184, 0.35);
  background: var(--surface);
  border-radius: 14px;
  padding: 0 14px;
  color: var(--text);
}

.type-filter-group {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.type-filter-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 42px;
  padding: 0 14px;
  border: 1px solid rgba(148, 163, 184, 0.28);
  border-radius: 999px;
  background: var(--surface);
  color: var(--text);
}

.type-filter-chip input {
  margin: 0;
}

.type-filter-chip:has(input:checked) {
  border-color: var(--primary);
  background: var(--primary-soft);
  color: var(--primary);
}

.study-toggle {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-height: 44px;
  padding: 0 14px;
  border: 1px solid rgba(148, 163, 184, 0.28);
  border-radius: 14px;
  background: var(--surface);
  color: var(--text);
}

.study-toggle input {
  margin: 0;
}

.question-title {
  margin: 12px 0;
  line-height: 1.65;
  font-size: 16px;
}

.options {
  display: grid;
  gap: 10px;
}

.option-item {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  border: 1px solid rgba(148, 163, 184, 0.22);
  border-radius: 14px;
  padding: 12px 14px;
  transition: all 0.2s ease;
}

.option-item input {
  margin-top: 2px;
}

.option-item.option-correct {
  border-color: rgba(22, 163, 74, 0.45);
  background: rgba(22, 163, 74, 0.08);
  color: #166534;
}

.option-item.option-wrong {
  border-color: rgba(220, 38, 38, 0.45);
  background: rgba(220, 38, 38, 0.08);
  color: #991b1b;
}

.fill-group {
  display: grid;
  gap: 10px;
}

.question-action-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-top: 12px;
}

.check-btn,
.complete-btn {
  min-height: 38px;
  padding: 0 14px;
}

.question-action-tip {
  color: var(--muted);
  font-size: 13px;
  line-height: 1.6;
}

.answer-tip {
  margin-top: 12px;
  color: var(--muted);
  font-size: 13px;
}

.result-box {
  border-radius: 16px;
  padding: 14px;
  margin-top: 14px;
  background: #f8fafc;
}

.trend-list {
  margin-top: 18px;
  display: flex;
  align-items: end;
  gap: 10px;
  min-height: 140px;
}

.trend-item {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
}

.trend-bar-wrap {
  width: 100%;
  height: 100px;
  display: flex;
  align-items: end;
}

.trend-bar {
  width: 100%;
  border-radius: 12px 12px 4px 4px;
  background: linear-gradient(180deg, #818cf8, #4f46e5);
  min-height: 12px;
}

.trend-label,
.trend-value {
  font-size: 12px;
  color: var(--muted);
}

.result-box.correct {
  background: rgba(22, 163, 74, 0.08);
  color: #166534;
}

.result-box.wrong {
  background: rgba(220, 38, 38, 0.08);
  color: #991b1b;
}

.result-row {
  margin-top: 8px;
  font-size: 14px;
  line-height: 1.6;
}

.wrong-book-item {
  border-color: rgba(220, 38, 38, 0.18);
}

.hidden {
  display: none;
}

@media (max-width: 640px) {
  .app-shell {
    padding: 14px 12px calc(28px + env(safe-area-inset-bottom, 0px));
  }

  .hero {
    padding: 22px 16px;
    border-radius: 20px;
  }

  .hero h1 {
    font-size: 23px;
  }

  .grid.two-cols,
  .controls-header,
  .paper-topbar,
  .result-header,
  .ios-card {
    grid-template-columns: 1fr;
    display: grid;
  }

  .primary-btn,
  .secondary-btn,
  .upload-btn {
    width: 100%;
  }

  .actions-row {
    flex-direction: column;
  }
}