*{margin:0;padding:0;box-sizing:border-box}
:root{
  --bg:#1a1e2a;--surface:#252a38;--card:#2e3446;--border:#3a4058;
  --text:#e8edf5;--muted:#8a92a8;--accent:#f59e0b;--accent2:#fb923c;
  --good:#22c55e;--warn:#ef4444;
  --card-back-1:#2a3048;--card-back-2:#333a50;
  --card-paper:#2e3446;--card-lines:rgba(255,255,255,0.04);--card-strip:var(--accent);
  --card-shadow-1:rgba(0,0,0,0.15);--card-shadow-2:rgba(0,0,0,0.25);--card-shadow-3:rgba(0,0,0,0.35);
  font-family:'Segoe UI',system-ui,sans-serif;
}
[data-theme="light"]{
  --bg:#f5f5f5;--surface:#ffffff;--card:#ffffff;--border:#e0e0e0;
  --text:#1a1a2e;--muted:#6b7280;--accent:#e8890b;--accent2:#ea7d2a;
  --good:#16a34a;--warn:#dc2626;
  --card-back-1:#fff8ee;--card-back-2:#fff3e0;
  --card-paper:#fffef9;--card-lines:rgba(0,100,200,0.06);--card-strip:var(--accent);
  --card-shadow-1:rgba(0,0,0,0.06);--card-shadow-2:rgba(0,0,0,0.1);--card-shadow-3:rgba(0,0,0,0.18);
}
body{background:var(--bg);color:var(--text);min-height:100vh;display:flex;flex-direction:column;align-items:center}

header{width:100%;padding:16px 24px;display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--border)}
.logo{font-size:22px;font-weight:700;letter-spacing:-0.5px}
.logo span{color:var(--accent)}
.header-right{display:flex;align-items:center;gap:12px}
.stats{font-size:13px;color:var(--muted)}
.theme-btn{width:32px;height:32px;border-radius:50%;border:1px solid var(--border);background:var(--surface);color:var(--text);cursor:pointer;font-size:16px;display:flex;align-items:center;justify-content:center;transition:all .2s}
.theme-btn:hover{border-color:var(--accent);color:var(--accent)}

.container{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:20px;width:100%;max-width:600px}

/* Mode toggle */
.mode-toggle{display:flex;gap:10px;margin-bottom:16px;align-items:center}
.mode-btn{width:46px;height:46px;padding:0;background:var(--surface);color:var(--muted);border:2px solid var(--border);border-radius:50%;cursor:pointer;font-size:22px;font-weight:700;line-height:1;transition:all .2s;display:flex;align-items:center;justify-content:center;position:relative}
.mode-btn:hover{border-color:var(--accent);color:var(--accent)}
.mode-btn.active{background:var(--accent);color:#000;border-color:var(--accent)}



/* Language selector */
.lang-wrap{position:relative}
.lang-menu{display:none;position:absolute;top:calc(100% + 6px);right:0;background:var(--surface);border:1px solid var(--border);border-radius:12px;box-shadow:0 8px 24px rgba(0,0,0,0.25);z-index:100;min-width:170px;padding:6px 0}
.lang-menu.visible{display:block}
.lang-item{display:flex;align-items:center;gap:8px;padding:8px 14px;font-size:13px;color:var(--text);cursor:pointer;transition:background .15s}
.lang-item:hover{background:rgba(245,158,11,0.08)}
.lang-item input[type="radio"]{accent-color:var(--accent);cursor:pointer}

/* Category filter */
.cat-wrap{position:relative}
.cat-menu{display:none;position:absolute;top:calc(100% + 6px);right:0;background:var(--surface);border:1px solid var(--border);border-radius:12px;box-shadow:0 8px 24px rgba(0,0,0,0.25);z-index:100;min-width:220px;max-height:400px;overflow:hidden;flex-direction:column}
.cat-menu.visible{display:flex}
.cat-menu-header{display:flex;gap:4px;padding:8px 10px;border-bottom:1px solid var(--border)}
.cat-menu-header button{flex:1;padding:6px 10px;border-radius:8px;border:1px solid var(--border);background:transparent;color:var(--text);font-size:12px;cursor:pointer;transition:all .2s}
.cat-menu-header button:hover{border-color:var(--accent);color:var(--accent)}
.cat-menu-list{overflow-y:auto;padding:6px 0;max-height:320px}
.cat-item{display:flex;align-items:center;gap:8px;padding:6px 14px;font-size:13px;color:var(--text);cursor:pointer;transition:background .15s}
.cat-item:hover{background:rgba(245,158,11,0.08)}
.cat-item input[type="checkbox"]{accent-color:var(--accent);width:15px;height:15px;cursor:pointer}

/* Search */
.search-box{display:none;width:100%;max-width:480px;margin-top:16px;margin-bottom:16px;position:relative}
.search-box.visible{display:block}
.search-icon{position:absolute;left:12px;top:50%;transform:translateY(-50%);width:16px;height:16px;color:var(--muted);pointer-events:none}
.search-box input{width:100%;padding:10px 36px 10px 36px;border-radius:20px;border:1px solid var(--border);background:var(--surface);color:var(--text);font-size:14px;outline:none;transition:border-color .2s}
.search-box input:focus{border-color:var(--accent)}
.search-clear{display:none;position:absolute;right:12px;top:50%;transform:translateY(-50%);color:var(--muted);cursor:pointer;font-size:14px;line-height:1;padding:2px}
.search-clear:hover{color:var(--accent)}

/* Card */
.card-wrapper{perspective:800px;width:100%;max-width:480px;height:280px;cursor:pointer;margin-bottom:24px;position:relative}
.card-wrapper::before{content:'';position:absolute;top:3px;left:2px;right:-2px;bottom:-4px;background:var(--card-paper);border:1px solid var(--border);border-radius:12px;transform:rotate(1.2deg);z-index:-2;box-shadow:0 2px 6px var(--card-shadow-1)}
.card-wrapper::after{content:'';position:absolute;top:5px;left:-1px;right:2px;bottom:-7px;background:var(--card-paper);border:1px solid var(--border);border-radius:12px;transform:rotate(-0.8deg);z-index:-3;box-shadow:0 2px 6px var(--card-shadow-1)}
.stack-card{position:absolute;top:0;left:0;right:0;bottom:0;background:var(--card-paper);border:1px solid var(--border);border-radius:12px;pointer-events:none}
.stack-3{top:7px;left:-3px;right:4px;bottom:-10px;transform:rotate(2deg);z-index:-4;box-shadow:0 2px 6px var(--card-shadow-1)}
.card{width:100%;height:100%;position:relative;transform-style:preserve-3d;transition:transform .5s;border-radius:12px}
.card.flipped{transform:rotateY(180deg)}
.card-face{position:absolute;width:100%;height:100%;backface-visibility:hidden;border-radius:12px;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:32px 24px 24px;border:1px solid var(--border);box-shadow:0 2px 4px var(--card-shadow-1),0 8px 20px var(--card-shadow-2);overflow:hidden}

/* Front: index card */
.card-front{background:var(--card-paper)}
.card-front::before{content:'';position:absolute;top:0;left:0;right:0;height:6px;background:var(--card-strip);border-radius:12px 12px 0 0;pointer-events:none}
.card-front::after{content:'';position:absolute;top:6px;left:0;right:0;height:40px;background:linear-gradient(to bottom,rgba(255,255,255,0.05),transparent);pointer-events:none}

/* Back */
.card-back{background:linear-gradient(135deg,var(--card-back-1),var(--card-back-2));transform:rotateY(180deg);border-color:var(--accent)}
.card-back::before{content:'';position:absolute;top:0;left:0;right:0;height:6px;background:var(--accent);border-radius:12px 12px 0 0;pointer-events:none}

.card-label{font-size:11px;color:var(--muted);text-transform:uppercase;letter-spacing:1.5px;margin-bottom:12px;position:relative;z-index:1}
.card-text{font-size:28px;font-weight:600;text-align:center;line-height:1.4;position:relative;z-index:1}
.card-back .card-text{color:var(--accent);font-size:28px}
.card-back .card-text-thai{font-size:18px;color:var(--muted);margin-top:8px}
.card-text-en{font-size:15px;font-weight:400;color:var(--muted);margin-top:6px;min-height:0}
.card-text-en:empty{display:none}

/* Favorite star */
.fav-star{position:absolute;top:10px;right:10px;z-index:10;background:none;border:none;font-size:22px;color:var(--muted);cursor:pointer;transition:all .2s;line-height:1;padding:4px}
.fav-star:hover{color:var(--accent);transform:scale(1.2)}
.fav-star.active{color:var(--accent)}



/* Favorite toolbar */
.fav-toolbar{display:none;gap:10px;margin-bottom:12px}
.fav-toolbar.visible{display:flex}

/* Speak button */
.speak-btn{position:absolute;top:10px;left:10px;z-index:10;background:none;border:none;font-size:20px;color:var(--muted);cursor:pointer;transition:all .2s;line-height:1;padding:4px}
.speak-btn:hover{color:var(--accent);transform:scale(1.2)}
.speak-btn.speaking{color:var(--accent);animation:pulse-speak .8s infinite}
@keyframes pulse-speak{0%,100%{transform:scale(1)}50%{transform:scale(1.3)}}

/* Browse toolbar */
.browse-toolbar{display:none;gap:10px;margin-bottom:12px}
.browse-toolbar.visible{display:flex}

/* Quiz toolbar */
.quiz-toolbar{display:none;gap:10px;margin-bottom:12px}
.quiz-toolbar.visible{display:flex}
.quiz-icon-btn{width:40px;height:40px;border-radius:50%;border:1px solid var(--border);background:var(--surface);color:var(--muted);cursor:pointer;display:flex;align-items:center;justify-content:center;transition:all .2s}
.quiz-icon-btn:hover{border-color:var(--accent);color:var(--accent)}
.quiz-icon-btn.active{background:var(--accent);color:#000;border-color:var(--accent)}

/* Controls */
.controls{display:flex;gap:12px;align-items:center}
.nav-btn{width:48px;height:48px;border-radius:50%;border:1px solid var(--border);background:var(--surface);color:var(--text);font-size:20px;cursor:pointer;display:flex;align-items:center;justify-content:center;transition:all .2s}
.nav-btn:hover{border-color:var(--accent);color:var(--accent)}
.counter{font-size:14px;color:var(--muted);min-width:80px;text-align:center}

.progress-bar{width:100%;max-width:480px;height:3px;background:var(--border);border-radius:2px;margin-bottom:20px;overflow:hidden}
.progress-fill{height:100%;background:var(--accent);border-radius:2px;transition:width .3s}

.quiz-choices{display:none;width:100%;max-width:480px;flex-direction:column;gap:8px;margin-bottom:16px}
.quiz-choices.visible{display:flex}
.choice-btn{padding:12px 20px;border-radius:12px;border:1px solid var(--border);background:var(--surface);color:var(--text);font-size:15px;cursor:pointer;transition:all .2s;text-align:left}
.choice-btn:hover{border-color:var(--accent);color:var(--accent)}
.choice-btn.correct{background:var(--good);color:#fff;border-color:var(--good)}
.choice-btn.wrong{background:var(--warn);color:#fff;border-color:var(--warn)}
.quiz-result{font-size:14px;margin-bottom:12px;min-height:20px}
.quiz-result.correct{color:var(--good)}
.quiz-result.wrong{color:var(--warn)}

@media(max-width:500px){
  .card-wrapper{height:220px}
  .card-text{font-size:22px}
  .card-back .card-text{font-size:20px}
  .card-back .card-text-thai{font-size:15px}
  .mode-btn{width:40px;height:40px;font-size:19px}
  .mode-toggle{gap:8px}
}