:root {
  --color-bg: #ffffff;
  --color-surface: #f5faf6;
  --color-surface-strong: #eaf4ec;
  --color-border: #e1e8e2;
  --color-primary: #7fae8e;
  --color-primary-dark: #5e8f6d;
  --color-text: #1d1d1f;
  --color-text-secondary: #6e6e73;
  --color-danger: #c0503f;
  --color-warning: #b8863a;
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.04), 0 8px 24px rgba(0, 0, 0, 0.05);
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang TC", "Microsoft JhengHei", "Helvetica Neue", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: var(--font);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-primary-dark);
}

.container {
  max-width: 920px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Nav */
nav.topnav {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--color-border);
}

nav.topnav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

nav.topnav .brand {
  font-weight: 600;
  font-size: 17px;
  text-decoration: none;
  color: var(--color-text);
}

nav.topnav .links {
  display: flex;
  gap: 4px;
}

nav.topnav .links a {
  text-decoration: none;
  color: var(--color-text-secondary);
  font-size: 14px;
  padding: 8px 14px;
  border-radius: 999px;
  transition: background 0.15s, color 0.15s;
}

nav.topnav .links a:hover {
  background: var(--color-surface);
}

nav.topnav .links a.active {
  background: var(--color-surface-strong);
  color: var(--color-primary-dark);
  font-weight: 600;
}

main {
  padding: 40px 0 80px;
}

/* Hero */
.hero {
  text-align: center;
  padding: 80px 24px 60px;
}

.hero h1 {
  font-size: 44px;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 16px;
}

.hero p.tagline {
  font-size: 19px;
  color: var(--color-text-secondary);
  max-width: 560px;
  margin: 0 auto 40px;
}

.hero-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  max-width: 880px;
  margin: 0 auto;
}

@media (max-width: 720px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }
  .hero h1 {
    font-size: 32px;
  }
}

.entry-card {
  display: block;
  text-decoration: none;
  color: inherit;
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 28px 22px;
  text-align: left;
  transition: transform 0.15s, box-shadow 0.15s;
}

.entry-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-card);
}

.entry-card .icon {
  font-size: 28px;
  margin-bottom: 12px;
  display: block;
}

.entry-card h3 {
  margin: 0 0 6px;
  font-size: 17px;
}

.entry-card p {
  margin: 0;
  font-size: 14px;
  color: var(--color-text-secondary);
}

/* Cards & sections */
.section {
  margin-bottom: 40px;
}

.section-title {
  font-size: 22px;
  font-weight: 700;
  margin: 0 0 6px;
  letter-spacing: -0.01em;
}

.section-hint {
  color: var(--color-text-secondary);
  font-size: 14px;
  margin: 0 0 20px;
}

.card {
  background: var(--color-surface);
  border-radius: var(--radius-md);
  padding: 20px;
  margin-bottom: 12px;
}

.card-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

/* Forms */
.field {
  margin-bottom: 16px;
}

.field label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text-secondary);
  margin-bottom: 6px;
}

input[type="text"],
input[type="url"],
input[type="date"],
input[type="number"],
input[type="file"],
select,
textarea {
  width: 100%;
  padding: 11px 14px;
  font-size: 15px;
  font-family: var(--font);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: #fff;
  color: var(--color-text);
}

textarea {
  resize: vertical;
  min-height: 100px;
}

input:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(127, 174, 142, 0.2);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 11px 20px;
  border-radius: 999px;
  border: none;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  background: var(--color-primary);
  color: #fff;
  transition: background 0.15s;
}

.btn:hover {
  background: var(--color-primary-dark);
}

.btn.secondary {
  background: var(--color-surface-strong);
  color: var(--color-text);
}

.btn.secondary:hover {
  background: var(--color-border);
}

.btn.danger {
  background: #fff;
  color: var(--color-danger);
  border: 1px solid var(--color-danger);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.row {
  display: flex;
  gap: 10px;
  align-items: flex-end;
  flex-wrap: wrap;
}

.row > * {
  flex: 1;
  min-width: 160px;
}

/* Subject bar (共用科目選單) */
.subject-bar {
  display: flex;
  gap: 10px;
  align-items: center;
  flex-wrap: wrap;
  background: var(--color-surface);
  padding: 14px 18px;
  border-radius: var(--radius-md);
  margin-bottom: 28px;
}

.subject-bar label {
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text-secondary);
}

.subject-bar select {
  width: auto;
  min-width: 140px;
}

.subject-bar .new-subject {
  display: flex;
  gap: 6px;
  margin-left: auto;
}

.subject-bar .new-subject input {
  width: 160px;
}

/* Badges */
.badge {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 999px;
}

.badge.verified {
  background: #e4f3e8;
  color: var(--color-primary-dark);
}

.badge.pending {
  background: #fbf1e0;
  color: var(--color-warning);
}

.badge.source {
  background: var(--color-surface-strong);
  color: var(--color-text-secondary);
}

/* Quiz */
.question-block {
  padding: 20px;
  background: var(--color-surface);
  border-radius: var(--radius-md);
  margin-bottom: 14px;
}

.question-block .q-text {
  font-weight: 600;
  margin-bottom: 12px;
}

.option-label {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  margin-bottom: 8px;
  background: #fff;
  border: 1px solid var(--color-border);
  cursor: pointer;
}

.option-label:hover {
  border-color: var(--color-primary);
}

.option-label.correct {
  border-color: var(--color-primary-dark);
  background: #e4f3e8;
}

.option-label.wrong {
  border-color: var(--color-danger);
  background: #fbeae7;
}

.citation {
  font-size: 12px;
  color: var(--color-text-secondary);
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px dashed var(--color-border);
}

.empty-hint {
  color: var(--color-text-secondary);
  font-size: 14px;
  padding: 24px;
  text-align: center;
  background: var(--color-surface);
  border-radius: var(--radius-md);
}

.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--color-text);
  color: #fff;
  padding: 12px 22px;
  border-radius: 999px;
  font-size: 14px;
  z-index: 100;
  opacity: 0;
  transition: opacity 0.2s;
  pointer-events: none;
}

.toast.show {
  opacity: 1;
}

.error-text {
  color: var(--color-danger);
  font-size: 14px;
}

.score-banner {
  text-align: center;
  padding: 32px;
  background: var(--color-surface-strong);
  border-radius: var(--radius-lg);
  margin-bottom: 24px;
}

.score-banner .score {
  font-size: 42px;
  font-weight: 700;
  color: var(--color-primary-dark);
}