/* ═══════════════════════════════════════════════════════
   Word Transformations — stylesheet
   ═══════════════════════════════════════════════════════ */

/* ── Reset & base ───────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  /* Category colours */
  --c-noun:        #3B82F6;   /* blue   */
  --c-verb:        #10B981;   /* emerald */
  --c-adjective:   #F59E0B;   /* amber  */
  --c-adverb:      #8B5CF6;   /* violet */
  --c-preposition: #EC4899;   /* pink   */
  --c-connector:   #06B6D4;   /* cyan   */
  --c-article:     #6B7280;   /* gray   */

  /* UI */
  --bg:        #F8FAFC;
  --surface:   #FFFFFF;
  --border:    #E2E8F0;
  --text:      #1E293B;
  --text-muted:#64748B;
  --radius:    12px;
  --shadow:    0 2px 12px rgba(0,0,0,.08);
  --shadow-lg: 0 8px 32px rgba(0,0,0,.12);

  --header-h: 64px;
  --sidebar-w: 300px;
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

/* ── Category colour helpers ────────────────────────────── */
.cat-noun        { --cat: var(--c-noun);        }
.cat-verb        { --cat: var(--c-verb);         }
.cat-adjective   { --cat: var(--c-adjective);    }
.cat-adverb      { --cat: var(--c-adverb);       }
.cat-preposition { --cat: var(--c-preposition);  }
.cat-connector   { --cat: var(--c-connector);    }
.cat-article-quantifier { --cat: var(--c-article); }

.category-badge {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .04em;
  text-transform: uppercase;
  background: var(--cat, #6B7280);
  color: #fff;
  white-space: nowrap;
}

/* ── Site header ────────────────────────────────────────── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-h);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  box-shadow: 0 1px 4px rgba(0,0,0,.06);
}
.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  height: 100%;
  padding: 0 1.25rem;
  display: flex;
  align-items: center;
  gap: 1.25rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: .5rem;
  flex-shrink: 0;
  font-size: 1.2rem;
  color: var(--text);
  text-decoration: none;
}
.logo-icon {
  font-size: 1.6rem;
  color: var(--c-verb);
  display: inline-block;
  animation: spin 8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.logo-text strong { color: var(--c-noun); }

/* Search */
.search-wrap {
  position: relative;
  flex: 1;
  max-width: 480px;
}
.search-wrap input {
  width: 100%;
  padding: .55rem 2.4rem .55rem 2.4rem;
  border: 2px solid var(--border);
  border-radius: 999px;
  font-size: .95rem;
  background: var(--bg);
  color: var(--text);
  outline: none;
  transition: border-color .2s;
}
.search-wrap input:focus { border-color: var(--c-noun); }
.search-icon {
  position: absolute;
  left: .8rem;
  top: 50%;
  transform: translateY(-50%);
  pointer-events: none;
  font-size: .9rem;
}

.search-dropdown {
  position: absolute;
  top: calc(100% + 6px);
  left: 0; right: 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  max-height: 320px;
  overflow-y: auto;
  z-index: 200;
}
.search-dropdown.hidden { display: none; }
.search-item {
  display: flex;
  align-items: center;
  gap: .75rem;
  padding: .6rem 1rem;
  cursor: pointer;
  transition: background .15s;
}
.search-item:hover { background: var(--bg); }
.search-item .si-word { font-weight: 600; }
.search-item .si-def  { font-size: .8rem; color: var(--text-muted); }

/* ── Layout ─────────────────────────────────────────────── */
.layout {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.25rem;
  display: flex;
  gap: 1.25rem;
  align-items: flex-start;
}

/* ── Sidebar ────────────────────────────────────────────── */
.sidebar {
  flex-shrink: 0;
  width: var(--sidebar-w);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  position: sticky;
  top: calc(var(--header-h) + 1.25rem);
  max-height: calc(100vh - var(--header-h) - 2.5rem);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}
.sidebar-toggle {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: .85rem 1rem;
  width: 100%;
  background: none;
  border: none;
  border-bottom: 1px solid var(--border);
  cursor: pointer;
  font-size: .9rem;
  font-weight: 600;
  color: var(--text);
  gap: .5rem;
}
.sidebar-toggle:hover { background: var(--bg); }
.chevron {
  transition: transform .3s;
  font-size: .7rem;
}
.sidebar.open .chevron { transform: rotate(90deg); }

.sidebar-content {
  overflow-y: auto;
  transition: max-height .35s ease;
  max-height: 0;
}
.sidebar-content:not(.collapsed) {
  max-height: calc(100vh - var(--header-h) - 6rem);
}
.sidebar-intro {
  padding: .75rem 1rem;
  font-size: .82rem;
  color: var(--text-muted);
  border-bottom: 1px solid var(--border);
}

.rule-item {
  border-bottom: 1px solid var(--border);
  padding: .75rem 1rem;
}
.rule-tag {
  display: inline-block;
  font-family: monospace;
  font-size: .85rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 6px;
  background: #EEF2FF;
  color: #4338CA;
  margin-bottom: .3rem;
}
.rule-desc {
  font-size: .78rem;
  color: var(--text-muted);
  margin-bottom: .5rem;
}
.rule-examples {
  display: flex;
  flex-wrap: wrap;
  gap: .35rem;
}
.rule-ex {
  font-size: .75rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 2px 7px;
  color: var(--text);
}
.rule-ex .arrow { color: var(--text-muted); margin: 0 2px; }

/* ── Main content ───────────────────────────────────────── */
.main-content { flex: 1; min-width: 0; }

/* Tabs */
.tab-nav {
  display: flex;
  gap: .4rem;
  margin-bottom: 1rem;
}
.tab-btn {
  padding: .55rem 1.1rem;
  border-radius: 999px;
  border: 2px solid transparent;
  background: var(--surface);
  font-size: .88rem;
  font-weight: 600;
  cursor: pointer;
  color: var(--text-muted);
  transition: all .2s;
  border-color: var(--border);
}
.tab-btn:hover { color: var(--text); }
.tab-btn.active {
  background: var(--c-noun);
  border-color: var(--c-noun);
  color: #fff;
}

.tab-panel { display: block; }
.tab-panel.hidden { display: none; }

/* ── Hero prompt ────────────────────────────────────────── */
.hero-prompt {
  text-align: center;
  padding: 2rem 1rem;
  color: var(--text-muted);
  font-size: .95rem;
}
.featured-pills {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: .5rem;
  margin-top: 1.25rem;
}
.featured-pill {
  padding: .4rem .9rem;
  border-radius: 999px;
  background: var(--surface);
  border: 2px solid var(--border);
  font-size: .85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all .2s;
  color: var(--text);
}
.featured-pill:hover {
  border-color: var(--c-noun);
  color: var(--c-noun);
  transform: translateY(-1px);
  box-shadow: var(--shadow);
}

/* ── Word card ──────────────────────────────────────────── */
.word-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  animation: fadeSlide .3s ease;
  margin-bottom: 1.25rem;
}
.word-card.hidden { display: none; }

@keyframes fadeSlide {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0);   }
}

.wc-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(135deg, #F8FAFC 0%, #EEF2FF 100%);
}
.wc-base {
  display: flex;
  align-items: center;
  gap: .75rem;
  margin-bottom: .5rem;
}
.wc-word {
  font-size: 2rem;
  font-weight: 800;
  color: var(--text);
}
.wc-def {
  font-size: .9rem;
  color: var(--text-muted);
  margin-bottom: .35rem;
}
.wc-example-base {
  font-size: .88rem;
  font-style: italic;
  color: var(--text-muted);
}
.wc-example-base::before { content: '"'; }
.wc-example-base::after  { content: '"'; }

.wc-transforms { padding: 1.25rem 1.5rem; }
.wc-transforms h3 {
  font-size: .8rem;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 1rem;
}
.wc-transform-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: .75rem;
}
.transform-item {
  background: var(--bg);
  border: 1px solid var(--border);
  border-left: 4px solid var(--cat, #6B7280);
  border-radius: 8px;
  padding: .75rem;
  cursor: pointer;
  transition: all .2s;
}
.transform-item:hover {
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}
.ti-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: .4rem;
}
.ti-word {
  font-weight: 700;
  font-size: 1rem;
}
.ti-example {
  font-size: .78rem;
  color: var(--text-muted);
  font-style: italic;
  line-height: 1.4;
}

/* ── Explorer grid ──────────────────────────────────────── */
.explorer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: .75rem;
}
.eg-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-top: 4px solid var(--cat, #6B7280);
  border-radius: var(--radius);
  padding: 1rem;
  cursor: pointer;
  transition: all .2s;
}
.eg-card:hover {
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}
.eg-word {
  font-weight: 700;
  font-size: 1.05rem;
  margin-bottom: .35rem;
}
.eg-family-count {
  font-size: .75rem;
  color: var(--text-muted);
}

/* ── Categories tab ─────────────────────────────────────── */
.cat-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem;
  margin-bottom: 1.25rem;
}
.cat-btn {
  padding: .55rem 1.1rem;
  border-radius: 999px;
  border: 2px solid var(--cat, #6B7280);
  background: transparent;
  color: var(--cat, #6B7280);
  font-weight: 700;
  font-size: .88rem;
  cursor: pointer;
  transition: all .2s;
}
.cat-btn:hover,
.cat-btn.active {
  background: var(--cat, #6B7280);
  color: #fff;
}

.cat-word-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: .75rem;
}
.cw-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 4px solid var(--cat, #6B7280);
  border-radius: 8px;
  padding: .85rem 1rem;
  cursor: pointer;
  transition: all .2s;
}
.cw-item:hover {
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}
.cw-word {
  font-weight: 700;
  font-size: 1rem;
  margin-bottom: .2rem;
}
.cw-def {
  font-size: .78rem;
  color: var(--text-muted);
}
.cw-example {
  font-size: .78rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: .25rem;
}

/* ── Quiz tab ───────────────────────────────────────────── */
.quiz-wrap { max-width: 600px; margin: 0 auto; }

.quiz-score-bar {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: .75rem 1.25rem;
  margin-bottom: 1.25rem;
  font-size: .9rem;
  flex-wrap: wrap;
}
.quiz-score-bar strong { color: var(--c-noun); }

.btn-ghost {
  margin-left: auto;
  padding: .3rem .8rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: none;
  font-size: .8rem;
  cursor: pointer;
  color: var(--text-muted);
  transition: all .2s;
}
.btn-ghost:hover { border-color: var(--text-muted); color: var(--text); }

.quiz-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.75rem;
  margin-bottom: 1rem;
  min-height: 220px;
}
.quiz-question {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
  line-height: 1.5;
  color: var(--text);
}

.quiz-options {
  display: grid;
  gap: .65rem;
}
.quiz-option {
  padding: .75rem 1.1rem;
  border-radius: 10px;
  border: 2px solid var(--border);
  background: var(--bg);
  font-size: .95rem;
  font-weight: 500;
  cursor: pointer;
  text-align: left;
  transition: all .2s;
  color: var(--text);
}
.quiz-option:hover:not(:disabled) {
  border-color: var(--c-noun);
  background: #EEF2FF;
}
.quiz-option.correct {
  border-color: var(--c-verb);
  background: #D1FAE5;
  color: #065F46;
}
.quiz-option.incorrect {
  border-color: #EF4444;
  background: #FEE2E2;
  color: #991B1B;
}
.quiz-option:disabled { cursor: default; }

.quiz-feedback {
  margin-top: 1rem;
  padding: .75rem 1rem;
  border-radius: 10px;
  font-size: .9rem;
  font-weight: 500;
}
.quiz-feedback.hidden { display: none; }
.quiz-feedback.correct-fb {
  background: #D1FAE5;
  color: #065F46;
  border: 1px solid #6EE7B7;
}
.quiz-feedback.incorrect-fb {
  background: #FEE2E2;
  color: #991B1B;
  border: 1px solid #FCA5A5;
}

.quiz-family {
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}
.quiz-family.hidden { display: none; }
.quiz-family h4 {
  font-size: .78rem;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: .6rem;
}
.qf-chips {
  display: flex;
  flex-wrap: wrap;
  gap: .4rem;
}
.qf-chip {
  display: flex;
  align-items: center;
  gap: .35rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: .25rem .6rem;
  font-size: .8rem;
}
.qf-chip .qf-word { font-weight: 600; }

.quiz-actions { text-align: center; }
.btn-primary {
  padding: .7rem 2rem;
  border-radius: 999px;
  border: none;
  background: var(--c-noun);
  color: #fff;
  font-size: .95rem;
  font-weight: 700;
  cursor: pointer;
  transition: all .2s;
  box-shadow: 0 4px 14px rgba(59,130,246,.35);
}
.btn-primary:hover {
  background: #2563EB;
  transform: translateY(-1px);
  box-shadow: 0 6px 18px rgba(59,130,246,.45);
}
.btn-primary:active { transform: none; }

/* ── Transformation Graph (SVG DAG) ─────────────────────── */
.word-pipeline {
  padding: 1.25rem 1.5rem 1rem;
  border-bottom: 1px solid var(--border);
  background: #FAFBFF;
}
.pipeline-title {
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: .75rem;
}

/* ── Utilities ──────────────────────────────────────────── */
.hidden { display: none !important; }

/* Replaces inline style="font-size:.65rem" — avoids unsafe-inline CSP */
.badge-sm { font-size: .65rem !important; margin-left: .4rem; }

/* Replaces inline style on parent-word reference in category list */
.parent-ref { font-size: .75rem; color: var(--text-muted); font-weight: 400; }

/* ── Mobile responsive ──────────────────────────────────── */
@media (max-width: 860px) {
  .layout { flex-direction: column; }
  .sidebar {
    width: 100%;
    position: static;
    max-height: none;
  }
  .sidebar-content {
    max-height: none;
  }
  .sidebar-content.collapsed { max-height: 0; overflow: hidden; }
}

@media (max-width: 520px) {
  .tab-nav { gap: .25rem; }
  .tab-btn { padding: .45rem .75rem; font-size: .8rem; }
  .wc-word { font-size: 1.5rem; }
  .quiz-score-bar { gap: .75rem; }
  .logo-text { display: none; }
}