/* ──────────────────────────────────────────────────────────────────────────── */
/* 中央 — Chinese Card Practice                                                 */
/* ──────────────────────────────────────────────────────────────────────────── */

/* ── Tokens ──────────────────────────────────────────────────────────────── */
:root {
  --bg-primary:        #0f172a;
  --bg-secondary:      #1e293b;
  --bg-card:           #1e293b;
  --bg-elevated:       #263347;
  --bg-hover:          #2d3f5a;
  --border-color:      #334155;
  --border-light:      #475569;
  --text-primary:      #f1f5f9;
  --text-secondary:    #94a3b8;
  --text-muted:        #64748b;
  --accent-gold:       #f59e0b;
  --accent-gold-dim:   #92400e;
  --accent-blue:       #3b82f6;
  --accent-emerald:    #10b981;
  --danger:            #ef4444;
  --font-hanzi:        'Noto Serif SC', 'Source Han Serif CN', 'PingFang SC', serif;
  --font-sans:         -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --header-h:          56px;
  --bottom-nav-h:      64px;
  --radius:            12px;
  --radius-sm:         8px;
  --shadow:            0 4px 24px rgba(0,0,0,.45);
}
[data-theme="light"] {
  --bg-primary:    #f8fafc;
  --bg-secondary:  #ffffff;
  --bg-card:       #ffffff;
  --bg-elevated:   #f1f5f9;
  --bg-hover:      #e2e8f0;
  --border-color:  #e2e8f0;
  --border-light:  #cbd5e1;
  --text-primary:  #1e293b;
  --text-secondary:#475569;
  --text-muted:    #94a3b8;
}

/* ── Reset ───────────────────────────────────────────────────────────────── */
*,*::before,*::after { box-sizing:border-box; margin:0; padding:0; }
html { font-size:16px; height:100%; -webkit-text-size-adjust:100%; }
body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
  transition: background .2s, color .2s;
}
a { color: inherit; text-decoration: none; }
button { cursor: pointer; border: none; background: none; font: inherit; color: inherit; }

/* ── Loading ─────────────────────────────────────────────────────────────── */
.loading-screen {
  position: fixed; inset: 0;
  background: var(--bg-primary);
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 1.25rem; z-index: 999;
  transition: opacity .3s;
}
.loading-screen.hidden { opacity: 0; pointer-events: none; }
.spinner {
  width: 42px; height: 42px;
  border: 3px solid var(--border-color);
  border-top-color: var(--accent-gold);
  border-radius: 50%;
  animation: spin .8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ── Layout ──────────────────────────────────────────────────────────────── */
.app-container {
  display: flex; flex-direction: column;
  min-height: 100vh;
  padding-top: var(--header-h);
  padding-bottom: var(--bottom-nav-h);
}
.main-content { flex: 1; max-width: 1200px; margin: 0 auto; width: 100%; padding: .75rem 1rem 1.5rem; }

/* ── Header ──────────────────────────────────────────────────────────────── */
.app-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: var(--header-h);
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  backdrop-filter: blur(12px);
}
.header-inner {
  max-width: 1200px; margin: 0 auto; height: 100%;
  display: flex; align-items: center; gap: 1rem; padding: 0 1rem;
}
.brand { display: flex; align-items: center; gap: .4rem; }

/* ── Desktop Nav ─────────────────────────────────────────────────────────── */
.desktop-nav { display: flex; gap: .25rem; flex: 1; margin-left: .75rem; }
.nav-tab {
  padding: .4rem .9rem; border-radius: var(--radius-sm);
  font-size: .85rem; font-weight: 500; color: var(--text-secondary);
  transition: all .15s;
}
.nav-tab:hover { background: var(--bg-hover); color: var(--text-primary); }
.nav-tab.active { background: var(--bg-hover); color: var(--accent-gold); }
.btn-icon { padding: .35rem .5rem; border-radius: var(--radius-sm); font-size: 1rem; transition: background .15s; }
.btn-icon:hover { background: var(--bg-hover); }

/* ── Bottom Nav ──────────────────────────────────────────────────────────── */
.bottom-nav {
  display: none;
  position: fixed; bottom: 0; left: 0; right: 0;
  height: var(--bottom-nav-h);
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  z-index: 100;
  padding-bottom: env(safe-area-inset-bottom, 0);
}
.bottom-nav-item {
  flex: 1; display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: .2rem; font-size: .72rem; font-weight: 500; color: var(--text-muted);
  transition: color .15s;
}
.bottom-nav-item .icon { font-size: 1.35rem; }
.bottom-nav-item.active { color: var(--accent-gold); }
@media (max-width: 720px) {
  .desktop-nav { display: none; }
  .bottom-nav { display: flex; }
}

/* ── View Panels ─────────────────────────────────────────────────────────── */
.view-panel { display: none; }
.view-panel.active { display: block; }

/* ── Cards View ──────────────────────────────────────────────────────────── */
.card-study-container { max-width: 560px; margin: 0 auto; }
.study-progress-bar { display: flex; align-items: center; padding: .25rem 0 .75rem; }
.flashcard {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 2.25rem 1.75rem;
  text-align: center;
  min-height: 280px;
  display: flex; flex-direction: column; justify-content: center; align-items: center; gap: 1.1rem;
  cursor: pointer;
  transition: border-color .15s;
}
.flashcard:hover { border-color: var(--border-light); }
.card-hanzi {
  font-family: var(--font-hanzi);
  font-size: clamp(2.8rem, 8vw, 4.5rem);
  line-height: 1.1;
  display: flex; flex-wrap: wrap; justify-content: center; gap: .1rem;
}
.card-pinyin  { font-size: 1.25rem; color: var(--accent-gold); font-weight: 600; transition: filter .2s; }
.card-english { font-size: 1rem; color: var(--text-secondary); line-height: 1.45; transition: filter .2s; }
.card-blurred { filter: blur(6px); user-select: none; }
.reveal-btn {
  margin-top: .5rem; padding: .55rem 1.5rem; border-radius: 999px;
  background: var(--accent-gold); color: #0f172a;
  font-weight: 600; font-size: .9rem;
  transition: opacity .15s;
}
.reveal-btn:hover { opacity: .85; }
.card-controls { display: flex; gap: .75rem; margin-top: 1rem; justify-content: center; }
.btn-ctrl {
  padding: .5rem 1.2rem; border-radius: var(--radius-sm); border: 1px solid var(--border-color);
  font-size: .9rem; font-weight: 500; background: var(--bg-elevated);
  transition: all .15s;
}
.btn-ctrl:hover { background: var(--bg-hover); border-color: var(--border-light); }
.btn-ctrl.btn-primary { background: var(--accent-gold); color: #0f172a; border-color: var(--accent-gold); }
.btn-ctrl.btn-primary:hover { opacity: .88; }

/* Clickable hanzi chars */
.hanzi-char {
  cursor: pointer; border-radius: 6px; padding: 0 2px;
  transition: all .15s; display: inline-block;
}
.hanzi-char:hover { background: var(--accent-gold); color: #0f172a; }
.match-highlight    { color: var(--accent-gold); font-weight: 700; }
.compound-highlight { color: var(--accent-emerald); }

/* ── Character Directory ─────────────────────────────────────────────────── */
.char-directory-header {
  display: flex; flex-direction: column; gap: .65rem;
  margin-bottom: 1rem;
  padding: .85rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
}
.search-input-wrapper {
  position: relative; display: flex; align-items: center;
}
.search-icon { position: absolute; left: .7rem; font-size: .95rem; pointer-events: none; }
.search-input {
  width: 100%; padding: .6rem .7rem .6rem 2.25rem;
  background: var(--bg-elevated); border: 1px solid var(--border-color);
  border-radius: var(--radius-sm); color: var(--text-primary);
  font-size: .9rem; font-family: var(--font-sans);
  transition: border-color .15s;
}
.search-input:focus { outline: none; border-color: var(--accent-gold); }
.search-input::placeholder { color: var(--text-muted); }
.search-clear-btn {
  position: absolute; right: .5rem; font-size: .85rem;
  color: var(--text-muted); padding: .25rem .4rem; border-radius: 4px;
}
.search-clear-btn:hover { background: var(--bg-hover); color: var(--text-primary); }

.char-filter-tabs { display: flex; gap: .4rem; flex-wrap: wrap; align-items: center; }
.filter-pill {
  padding: .3rem .8rem; border-radius: 999px; font-size: .8rem; font-weight: 500;
  border: 1px solid var(--border-color); color: var(--text-secondary);
  background: var(--bg-elevated);
  transition: all .15s;
}
.filter-pill:hover { border-color: var(--border-light); color: var(--text-primary); }
.filter-pill.active { background: var(--accent-gold); color: #0f172a; border-color: var(--accent-gold); }

/* Char Grid */
.char-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(62px, 1fr));
  gap: .45rem;
  margin-bottom: .75rem;
}
.char-tile {
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  padding: .55rem .25rem .4rem;
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius-sm); cursor: pointer;
  transition: all .12s; text-align: center;
}
.char-tile:hover { background: var(--bg-hover); border-color: var(--accent-gold); transform: translateY(-1px); }
.tile-hz   { font-family: var(--font-hanzi); font-size: 1.65rem; line-height: 1.1; }
.tile-py   { font-size: .62rem; color: var(--accent-gold); margin-top: .15rem; font-weight: 500; }
.tile-freq { font-size: .55rem; color: var(--text-muted); margin-top: .05rem; }

/* Pagination */
.pagination-bar {
  display: flex; align-items: center; justify-content: center;
  flex-wrap: wrap; gap: .3rem; margin: .75rem 0 1rem;
}
.page-btn {
  min-width: 32px; height: 32px; padding: 0 .45rem;
  border-radius: var(--radius-sm); border: 1px solid var(--border-color);
  background: var(--bg-elevated); font-size: .82rem; font-weight: 500;
  color: var(--text-secondary); transition: all .13s;
}
.page-btn:hover:not(:disabled) { background: var(--bg-hover); border-color: var(--border-light); color: var(--text-primary); }
.page-btn.active { background: var(--accent-gold); color: #0f172a; border-color: var(--accent-gold); }
.page-btn:disabled { opacity: .35; cursor: default; }

/* ── Character Modal ─────────────────────────────────────────────────────── */
.modal-backdrop {
  display: none;
  position: fixed; inset: 0; z-index: 200;
  background: rgba(0,0,0,.7);
  padding: .75rem;
  align-items: center; justify-content: center;
  overflow-y: auto;
}
.modal-backdrop.open { display: flex; }
.char-modal {
  width: 100%; max-width: 620px;
  max-height: calc(100vh - 1.5rem);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  display: flex; flex-direction: column;
  box-shadow: var(--shadow);
  overflow: hidden;
}
.modal-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: .75rem 1rem;
  border-bottom: 1px solid var(--border-color);
  flex-shrink: 0;
}
.modal-close-btn {
  font-size: 1rem; padding: .3rem .55rem; border-radius: var(--radius-sm);
  color: var(--text-muted); transition: all .15s;
}
.modal-close-btn:hover { background: var(--bg-hover); color: var(--text-primary); }
.modal-body { overflow-y: auto; padding: 1rem; display: flex; flex-direction: column; gap: .9rem; }

/* Hero */
.char-hero-section {
  display: flex; align-items: flex-start; justify-content: space-between; gap: 1rem;
}
.char-hero-left { display: flex; align-items: center; gap: 1rem; }
.hero-hz {
  font-family: var(--font-hanzi);
  font-size: 4rem; line-height: 1; flex-shrink: 0;
  color: var(--accent-gold);
}
.hero-py   { font-size: 1.25rem; font-weight: 600; color: var(--accent-gold); }
.hero-def  { font-size: .9rem; color: var(--text-secondary); margin-top: .2rem; }
.hero-badges { display: flex; flex-direction: column; gap: .35rem; align-items: flex-end; }
.badge-pill {
  padding: .25rem .6rem; border-radius: 999px; font-size: .72rem; font-weight: 500;
  white-space: nowrap;
}
.badge-freq { background: rgba(245,158,11,.12); color: var(--accent-gold); border: 1px solid rgba(245,158,11,.25); }
.badge-rad  { background: var(--bg-elevated); color: var(--text-secondary); border: 1px solid var(--border-color); }

/* Modal Sections */
.modal-section { display: flex; flex-direction: column; gap: .5rem; }
.section-title {
  display: flex; align-items: center; justify-content: space-between;
  font-size: .78rem; font-weight: 700; color: var(--text-muted);
  text-transform: uppercase; letter-spacing: .05em;
  padding-bottom: .35rem; border-bottom: 1px solid var(--border-color);
}
.section-desc { font-size: .86rem; color: var(--text-secondary); line-height: 1.55; }

/* Compound pills in modal */
.compound-pills-wrap { display: flex; flex-wrap: wrap; gap: .4rem; }
.compound-pill {
  display: flex; align-items: center; gap: .35rem;
  padding: .3rem .7rem; border-radius: 999px; font-size: .83rem; font-weight: 500;
  border: 1px solid var(--border-color); background: var(--bg-elevated);
  font-family: var(--font-hanzi); color: var(--text-primary);
  transition: all .13s;
}
.compound-pill .count { font-size: .7rem; color: var(--text-muted); font-family: var(--font-sans); }
.compound-pill:hover { border-color: var(--accent-gold); background: var(--bg-hover); }
.compound-pill.active { background: var(--accent-gold); color: #0f172a; border-color: var(--accent-gold); }
.compound-pill.active .count { color: rgba(0,0,0,.55); }

/* Active filter bar */
.active-compound-filter-bar {
  display: flex; align-items: center; justify-content: space-between;
  padding: .4rem .65rem; border-radius: var(--radius-sm);
  background: rgba(245,158,11,.08); border: 1px solid rgba(245,158,11,.2);
  font-size: .8rem; color: var(--accent-gold);
}
.reset-filter-btn {
  font-size: .75rem; color: var(--text-muted); padding: .2rem .4rem;
  border-radius: 4px; transition: all .13s;
}
.reset-filter-btn:hover { color: var(--text-primary); background: var(--bg-hover); }

/* Cross-deck card list */
.cross-cards-list { display: flex; flex-direction: column; gap: .4rem; }
.cross-card-item {
  padding: .65rem .75rem; border-radius: var(--radius-sm);
  background: var(--bg-elevated); border: 1px solid var(--border-color);
  cursor: pointer; transition: border-color .13s;
}
.cross-card-item:hover { border-color: var(--accent-gold); }
.cross-card-hz { font-family: var(--font-hanzi); font-size: 1.35rem; }
.cross-card-py { font-size: .8rem; color: var(--accent-gold); margin-top: .15rem; font-weight: 500; }
.cross-card-en { font-size: .8rem; color: var(--text-secondary); margin-top: .1rem; }

/* ── Slang View ──────────────────────────────────────────────────────────── */
.slang-container { max-width: 900px; margin: 0 auto; display: flex; flex-direction: column; gap: 1rem; }
.slang-intro-card {
  background: var(--bg-secondary); border: 1px solid var(--border-color);
  border-radius: var(--radius); padding: 1rem;
  display: flex; flex-direction: column; gap: .65rem;
}
.slang-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: .75rem;
}
.slang-card {
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius); padding: .9rem;
  display: flex; flex-direction: column; gap: .75rem;
  transition: border-color .15s;
}
.slang-card:hover { border-color: var(--border-light); }
.slang-header { display: flex; justify-content: space-between; align-items: flex-start; gap: .5rem; margin-bottom: .2rem; }
.slang-word { font-family: var(--font-hanzi); font-size: 1.5rem; line-height: 1.1; color: var(--accent-gold); }
.slang-py { font-size: .85rem; color: var(--text-secondary); font-weight: 500; }
.slang-badge {
  font-size: .65rem; font-weight: 600; padding: .2rem .5rem; border-radius: 999px;
  background: var(--bg-elevated); border: 1px solid var(--border-color);
  color: var(--text-muted); white-space: nowrap; flex-shrink: 0;
}
.slang-meaning { font-size: .9rem; color: var(--text-primary); font-weight: 500; }
.slang-note { font-size: .8rem; color: var(--text-secondary); line-height: 1.5; }
.slang-example {
  background: var(--bg-elevated); border-radius: var(--radius-sm); padding: .65rem;
  display: flex; flex-direction: column; gap: .2rem;
}
.slang-ex-hz { font-family: var(--font-hanzi); font-size: 1.2rem; }
.slang-ex-py { font-size: .75rem; color: var(--accent-gold); }
.slang-ex-en { font-size: .75rem; color: var(--text-secondary); margin-top: .15rem; font-style: italic; }

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

/* ── Responsive ──────────────────────────────────────────────────────────── */
@media (max-width: 480px) {
  .main-content { padding: .5rem .6rem 1rem; }
  .card-hanzi { font-size: clamp(2.2rem, 11vw, 3.5rem); }
  .char-grid { grid-template-columns: repeat(auto-fill, minmax(55px, 1fr)); gap: .35rem; }
  .char-modal { max-height: 95vh; }
  .hero-hz { font-size: 3rem; }
  .slang-grid { grid-template-columns: 1fr; }
}