:root {
  --color-bg: #ffffff;
  --color-text: #1a1a2e;
  --color-muted: #5b5b70;
  --color-border: #e2e2ec;
  --color-brand: #3730a3;
  --color-brand-hover: #2c2680;
  --color-easy: #1a7f37;
  --color-medium: #9a6700;
  --color-hard: #b3261e;
  --radius: 10px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.55;
}

.wrap { max-width: 960px; margin: 0 auto; padding: 0 20px; }

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

h1, h2 { line-height: 1.25; }

/* Header */
.site-header { border-bottom: 1px solid var(--color-border); }
.site-header .wrap { position: relative; display: flex; align-items: center; justify-content: space-between; padding-top: 6px; padding-bottom: 6px; flex-wrap: wrap; gap: 12px; }
.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; font-size: 1.25rem; color: var(--color-text); }
.brand-logo { flex-shrink: 0; }
.site-nav a { margin-left: 18px; color: var(--color-text); font-weight: 500; }
.site-nav a:first-child { margin-left: 0; }
.nav-toggle { display: none; background: none; border: none; padding: 6px; width: 40px; height: 40px; align-items: center; justify-content: center; cursor: pointer; color: var(--color-text); }
.nav-toggle svg { width: 24px; height: 24px; }

@media (max-width: 640px) {
  .nav-toggle { display: flex; }
  .site-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    box-shadow: 0 8px 16px rgba(0,0,0,0.08);
    padding: 4px 20px 12px;
  }
  .site-nav.open { display: flex; }
  .site-nav a { margin-left: 0; padding: 12px 0; border-top: 1px solid var(--color-border); }
  .site-nav a:first-child { border-top: none; }
}

.site-main { max-width: 960px; margin: 0 auto; padding: 32px 20px 64px; }

/* Footer */
.site-footer { border-top: 1px solid var(--color-border); margin-top: 40px; }
.site-footer .wrap { padding: 20px; color: var(--color-muted); font-size: 0.9rem; }

/* Hero */
.hero { text-align: center; padding: 32px 0 8px; }
.hero p { color: var(--color-muted); max-width: 640px; margin: 12px auto 24px; }
.exam-links { display: flex; justify-content: center; gap: 12px; flex-wrap: wrap; }
.exam-link { border: 1px solid var(--color-border); border-radius: var(--radius); padding: 10px 20px; font-weight: 600; }
.exam-link:hover { border-color: var(--color-brand); text-decoration: none; }

/* Breadcrumb */
.breadcrumb { font-size: 0.9rem; color: var(--color-muted); margin-bottom: 4px; }

/* A-Z index nav */
.alphabet-nav { display: flex; flex-wrap: wrap; gap: 6px; margin: 20px 0 28px; }
.alpha-link { display: inline-flex; align-items: center; justify-content: center; min-width: 38px; padding: 7px 4px; border: 1px solid var(--color-border); border-radius: var(--radius); font-weight: 600; }
.alpha-link:hover { border-color: var(--color-brand); text-decoration: none; }
.alpha-link.is-current { background: var(--color-brand); border-color: var(--color-brand); color: #fff; }
.alpha-link.is-empty { color: var(--color-muted); opacity: 0.45; }

/* Badges */
.badge { display: inline-block; border-radius: 999px; padding: 2px 10px; font-size: 0.75rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.02em; }
.badge-difficulty-easy { background: rgba(26,127,55,0.12); color: var(--color-easy); }
.badge-difficulty-medium { background: rgba(154,103,0,0.12); color: var(--color-medium); }
.badge-difficulty-hard { background: rgba(179,38,30,0.12); color: var(--color-hard); }

/* Word list grid */
.word-list-grid { list-style: none; padding: 0; display: grid; gap: 16px; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); }
.word-list-grid li { border: 1px solid var(--color-border); border-radius: var(--radius); padding: 16px; }
.word-count { color: var(--color-muted); font-size: 0.85rem; }

/* Word cards */
.word-grid { display: grid; gap: 14px; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); margin-top: 20px; }
.word-card { display: block; border: 1px solid var(--color-border); border-radius: var(--radius); padding: 16px; color: var(--color-text); }
.word-card:hover { border-color: var(--color-brand); text-decoration: none; }
.word-card-head { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.word-card-headword { font-weight: 700; font-size: 1.1rem; }
.word-card .pos { color: var(--color-muted); font-size: 0.8rem; font-style: italic; }
.word-card-def { margin: 8px 0 0; color: var(--color-muted); }

.quiz-cta { display: inline-block; margin-top: 12px; font-weight: 600; }

.list-actions { display: flex; align-items: center; gap: 18px; flex-wrap: wrap; margin-top: 12px; }
.list-actions .quiz-cta { margin-top: 0; }
.list-action-link { background: none; border: none; padding: 0; font: inherit; color: var(--color-brand); cursor: pointer; text-decoration: underline; }
.list-action-link:hover { color: var(--color-brand-hover); }

/* Word detail page */
.word-detail header { display: flex; align-items: baseline; gap: 12px; flex-wrap: wrap; }
.word-detail .pronunciation { color: var(--color-muted); }
.word-detail .pos { color: var(--color-muted); font-style: italic; }
.definition { font-size: 1.15rem; margin-top: 12px; }
.example { border-left: 3px solid var(--color-brand); margin: 16px 0; padding: 4px 16px; color: var(--color-muted); font-style: italic; }
.mnemonic, .relations, .appears-in { margin-top: 24px; }
.mnemonic h2, .relations h2, .appears-in h2 { font-size: 1rem; text-transform: uppercase; letter-spacing: 0.04em; color: var(--color-muted); }
.relations ul, .appears-in ul { padding-left: 20px; }

.share-links { margin-top: 32px; padding-top: 20px; border-top: 1px solid var(--color-border); display: flex; align-items: center; gap: 14px; flex-wrap: wrap; }
.share-label { color: var(--color-muted); font-size: 0.9rem; }
.wotd-permalink { margin-top: 28px; font-weight: 600; }
.wotd-note { color: var(--color-muted); font-size: 0.9rem; }

/* Quiz */
.quiz-question { border: none; border-top: 1px solid var(--color-border); padding: 16px 0; }
.quiz-question legend { font-weight: 600; padding: 0 0 8px; }
.quiz-choice { display: block; padding: 8px 10px; border-radius: 8px; cursor: pointer; }
.quiz-choice:hover { background: rgba(55,48,163,0.06); }
.quiz-choice input { margin-right: 8px; }
.quiz-correct-answer { background: rgba(26,127,55,0.10); }
.quiz-selected-wrong { background: rgba(179,38,30,0.10); }
#quiz-submit { margin-top: 20px; padding: 10px 24px; background: var(--color-brand); color: #fff; border: none; border-radius: var(--radius); font-weight: 600; cursor: pointer; }
#quiz-submit:hover { background: var(--color-brand-hover); }
#quiz-submit:disabled { opacity: 0.6; cursor: not-allowed; }
.quiz-result { margin-top: 20px; font-size: 1.2rem; font-weight: 700; }

/* Guides */
.guides-list { list-style: none; padding: 0; }
.guides-list li { border-bottom: 1px solid var(--color-border); padding: 14px 0; }
.guide-content { margin-top: 16px; }
.guide-content p { margin: 0 0 16px; }
.guide-content h2 { font-size: 1.2rem; margin: 28px 0 12px; }
.guide-content ul { margin: 0 0 16px; padding-left: 20px; }
.guide-content li { margin-bottom: 6px; }
.guide-exam-tag { color: var(--color-muted); font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.04em; }

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #14141f;
    --color-text: #ececf5;
    --color-muted: #a4a4bd;
    --color-border: #2c2c3d;
    --color-brand: #a5b4fc;
    --color-brand-hover: #c7d2fe;
  }
}

@media print {
  .site-header, .site-footer, .no-print { display: none !important; }
  .site-main { padding: 0; max-width: none; }
  body { color: #000; background: #fff; }
  a { color: #000; text-decoration: none; }
  .word-grid { display: block; }
  .word-card { border: none; border-bottom: 1px solid #ccc; border-radius: 0; padding: 10px 0; break-inside: avoid; }
  .badge { background: none !important; border: 1px solid #999; }
}