/* ═══════════════════════════════════════════════════════
   SỬ KÝ — Design Tokens + Reset
   Á Đông Cổ Trang — Tươi Sáng, Tích Cực
   ══════════════════════════════════════════════════════ */
@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+TC:wght@400;600;700;900&family=Inter:wght@300;400;500;600;700&display=swap');
:root{
  --cream:#FFF8F0;--cream-deep:#F5EDE0;--parchment:#F8F0E3;
  --red:#C53030;--red-lt:#E8524F;--red-dk:#9B2C2C;--red-bg:rgba(197,48,48,.08);
  --gold:#D4A843;--gold-lt:#E8C76A;--gold-dk:#B8922F;--gold-bg:rgba(212,168,67,.1);
  --teal:#2B8A6E;--teal-lt:#38B99A;--teal-dk:#1F6B55;--teal-bg:rgba(43,138,110,.08);
  --sky:#3B82C4;--sky-bg:rgba(59,130,196,.08);
  --ch:#2D2A26;--ch70:rgba(45,42,38,.7);--ch50:rgba(45,42,38,.5);
  --ch30:rgba(45,42,38,.3);--ch10:rgba(45,42,38,.1);
  --ok:#2D8B4E;--ok-bg:rgba(45,139,78,.1);
  --no:#C53030;--no-bg:rgba(197,48,48,.08);
  --white:#fff;
  --sh-sm:0 2px 12px rgba(45,42,38,.08);--sh-md:0 4px 20px rgba(45,42,38,.12);
  --sh-lg:0 8px 32px rgba(45,42,38,.15);--sh-gold:0 4px 16px rgba(212,168,67,.2);
  --serif:'Noto Serif TC',Georgia,serif;--sans:'Inter',-apple-system,sans-serif;
  --r-sm:4px;--r-md:8px;--r-lg:12px;--r-xl:16px;--r-2xl:24px;
  --ease:cubic-bezier(.4,0,.2,1);--spring:cubic-bezier(.34,1.56,.64,1);
  --sidebar-w:260px;
}
*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
html{font-size:16px;scroll-behavior:smooth;-webkit-font-smoothing:antialiased}
body{font-family:var(--sans);color:var(--ch);background:var(--cream);line-height:1.5;min-height:100vh}
h1,h2,h3,h4,h5,h6{font-family:var(--serif);font-weight:700;line-height:1.25}
a{color:var(--red);text-decoration:none}
img{display:block;max-width:100%}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);border:0}
.icon{display:inline-flex;align-items:center;justify-content:center;width:1em;height:1em;flex-shrink:0;vertical-align:middle}
.icon svg{width:100%;height:100%;display:block}

/* ── Motifs ── */
.motif-corners{position:relative}
.motif-corners::before,.motif-corners::after{content:'';position:absolute;width:20px;height:20px;border-color:var(--gold);border-style:solid;opacity:.4}
.motif-corners::before{top:8px;left:8px;border-width:2px 0 0 2px}
.motif-corners::after{top:8px;right:8px;border-width:2px 2px 0 0}
.motif-divider{display:flex;align-items:center;gap:16px;margin:24px 0;color:var(--ch30)}
.motif-divider::before,.motif-divider::after{content:'';flex:1;height:1px;background:linear-gradient(90deg,transparent,var(--gold) 20%,var(--gold) 80%,transparent);opacity:.35}
.ink-underline{position:relative;display:inline-block}
.ink-underline::after{content:'';position:absolute;bottom:-4px;left:0;width:100%;height:3px;background:linear-gradient(90deg,var(--red),var(--gold),transparent);border-radius:2px;opacity:.6}
.gold-line{width:60px;height:3px;background:linear-gradient(90deg,var(--gold),var(--gold-lt));border-radius:2px;margin:8px 0}
.parchment-bg{background:radial-gradient(ellipse at 10% 10%,rgba(212,168,67,.04) 0%,transparent 50%),radial-gradient(ellipse at 90% 90%,rgba(197,48,48,.03) 0%,transparent 50%),var(--cream)}
@keyframes fade-up{from{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}
@keyframes fade-in{from{opacity:0}to{opacity:1}}
@keyframes slide-right{from{opacity:0;transform:translateX(30px)}to{opacity:1;transform:translateX(0)}}
@keyframes pulse-glow{0%,100%{box-shadow:0 0 0 0 rgba(212,168,67,.4)}50%{box-shadow:0 0 0 8px rgba(212,168,67,0)}}
@keyframes shake{0%,100%{transform:translateX(0)}20%,60%{transform:translateX(-4px)}40%,80%{transform:translateX(4px)}}
@keyframes ink-splash{0%{transform:scale(0);opacity:.8}50%{transform:scale(1.2);opacity:.4}100%{transform:scale(1);opacity:0}}
.anim-up{animation:fade-up .5s var(--ease) both}
.anim-in{animation:fade-in .3s var(--ease) both}
.stagger>*:nth-child(1){animation-delay:0ms}.stagger>*:nth-child(2){animation-delay:80ms}
.stagger>*:nth-child(3){animation-delay:160ms}.stagger>*:nth-child(4){animation-delay:240ms}
.stagger>*:nth-child(5){animation-delay:320ms}.stagger>*:nth-child(6){animation-delay:400ms}
.stagger>*:nth-child(7){animation-delay:480ms}.stagger>*:nth-child(8){animation-delay:560ms}
.bg-pattern{position:fixed;inset:0;pointer-events:none;z-index:0;opacity:.03;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='80' height='80'%3E%3Cpath d='M40 10C30 10 20 20 20 30c0 10 10 20 20 15 10 5 20-5 20-15 0-10-10-20-20-20z' fill='none' stroke='%23D4A843' stroke-width='.5'/%3E%3C/svg%3E");background-size:80px}

/* ── Buttons ── */
.btn{display:inline-flex;align-items:center;gap:8px;padding:10px 24px;border:none;border-radius:var(--r-md);font-family:var(--sans);font-size:14px;font-weight:600;cursor:pointer;transition:all .25s var(--ease);line-height:1;white-space:nowrap}
.btn svg{width:16px;height:16px;flex-shrink:0}
.btn-primary{background:linear-gradient(135deg,var(--red),var(--red-dk));color:var(--white);box-shadow:var(--sh-sm)}
.btn-primary:hover{background:linear-gradient(135deg,var(--red-lt),var(--red));box-shadow:var(--sh-md);transform:translateY(-1px)}
.btn-gold{background:linear-gradient(135deg,var(--gold),var(--gold-dk));color:var(--white);box-shadow:var(--sh-gold)}
.btn-gold:hover{transform:translateY(-1px)}
.btn-outline{background:transparent;border:1.5px solid var(--ch30);color:var(--ch)}
.btn-outline:hover{border-color:var(--red);color:var(--red);background:var(--red-bg)}
.btn-ghost{background:transparent;color:var(--ch70);padding:8px 12px}
.btn-ghost:hover{background:var(--ch10);color:var(--ch)}
.btn-teal{background:linear-gradient(135deg,var(--teal),var(--teal-dk));color:var(--white)}
.btn-teal:hover{transform:translateY(-1px)}
.btn-lg{padding:14px 32px;font-size:16px;border-radius:var(--r-lg)}
.btn-sm{padding:6px 16px;font-size:12px}
.btn-block{width:100%;justify-content:center}

/* ── Cards ── */
.card{background:var(--white);border-radius:var(--r-lg);box-shadow:var(--sh-sm);padding:24px;transition:box-shadow .25s,transform .25s}
.card:hover{box-shadow:var(--sh-md)}
.card-3d{perspective:800px}
.card-3d:hover .card-inner{transform:rotateX(-2deg) rotateY(3deg) translateZ(8px);box-shadow:0 10px 30px rgba(45,42,38,.12),0 4px 12px rgba(212,168,67,.15)}
.card-inner{transition:transform .4s var(--spring),box-shadow .4s var(--ease)}
.card-gold{border:1px solid rgba(212,168,67,.2)}

/* ── Badges ── */
.badge{display:inline-flex;align-items:center;gap:4px;padding:2px 10px;border-radius:var(--r-2xl);font-size:12px;font-weight:600;line-height:1.6}
.badge-green{background:var(--ok-bg);color:var(--ok)}.badge-red{background:var(--no-bg);color:var(--no)}
.badge-gold{background:var(--gold-bg);color:var(--gold-dk)}.badge-teal{background:var(--teal-bg);color:var(--teal)}
.badge-sky{background:var(--sky-bg);color:var(--sky)}.badge-muted{background:var(--ch10);color:var(--ch50)}
.dot{display:inline-block;width:8px;height:8px;border-radius:50%;margin-right:6px}
.dot-active{background:var(--ok)}.dot-closed{background:var(--ch30)}.dot-waiting{background:var(--gold)}

/* ── Forms ── */
.form-group{margin-bottom:20px}
.form-label{display:block;font-size:14px;font-weight:600;margin-bottom:8px}
.form-input,.form-select,.form-textarea{width:100%;padding:10px 16px;border:1.5px solid var(--ch10);border-radius:var(--r-md);font-family:var(--sans);font-size:14px;color:var(--ch);background:var(--white);transition:border-color .15s,box-shadow .15s}
.form-input:focus,.form-select:focus,.form-textarea:focus{outline:none;border-color:var(--gold);box-shadow:0 0 0 3px var(--gold-bg)}
.form-input::placeholder{color:var(--ch30)}
.form-textarea{min-height:100px;resize:vertical}

/* ── Tables ── */
.table-wrap{overflow-x:auto;border-radius:var(--r-lg);box-shadow:var(--sh-sm)}
.table{width:100%;border-collapse:collapse;background:var(--white);font-size:14px}
.table th{padding:12px 16px;text-align:left;font-weight:600;color:var(--ch70);background:var(--cream-deep);border-bottom:2px solid var(--ch10);font-size:12px;text-transform:uppercase;letter-spacing:.05em}
.table td{padding:12px 16px;border-bottom:1px solid var(--ch10);vertical-align:middle}
.table tr:last-child td{border-bottom:none}
.table tr:hover td{background:rgba(212,168,67,.03)}

/* ── Tabs ── */
.tabs{display:flex;gap:4px;border-bottom:2px solid var(--ch10);margin-bottom:24px}
.tab-btn{display:flex;align-items:center;gap:8px;padding:12px 20px;border:none;background:transparent;color:var(--ch50);font-family:var(--sans);font-size:14px;font-weight:500;cursor:pointer;border-bottom:2px solid transparent;margin-bottom:-2px;transition:all .15s}
.tab-btn svg{width:16px;height:16px}
.tab-btn:hover{color:var(--ch)}
.tab-btn.active{color:var(--red);border-bottom-color:var(--red);font-weight:600}

/* ── Modal ── */
.modal-overlay{position:fixed;inset:0;background:rgba(45,42,38,.5);backdrop-filter:blur(4px);display:flex;align-items:center;justify-content:center;z-index:1000;opacity:0;visibility:hidden;transition:all .25s}
.modal-overlay.visible{opacity:1;visibility:visible}
.modal{background:var(--white);border-radius:var(--r-xl);box-shadow:var(--sh-lg);max-width:600px;width:90%;max-height:85vh;overflow-y:auto;transform:scale(.95) translateY(10px);transition:transform .25s var(--spring)}
.modal-overlay.visible .modal{transform:scale(1) translateY(0)}
.modal-header{padding:24px 24px 0;display:flex;align-items:center;justify-content:space-between}
.modal-body{padding:24px}.modal-footer{padding:0 24px 24px;display:flex;justify-content:flex-end;gap:12px}

/* ── AI Panel ── */
.ai-panel{background:linear-gradient(135deg,var(--teal-bg),rgba(43,138,110,.02));border:1px solid rgba(43,138,110,.15);border-radius:var(--r-lg);padding:20px}
.ai-panel-head{display:flex;align-items:center;gap:8px;margin-bottom:12px;font-weight:600;color:var(--teal-dk)}
.ai-panel-head svg{width:20px;height:20px}
.ai-panel-body{font-size:14px;color:var(--ch70);line-height:1.75}

/* ── Score Badge ── */
.score-badge{display:inline-flex;align-items:center;justify-content:center;width:80px;height:80px;border-radius:50%;border:4px solid var(--gold);background:var(--white);box-shadow:var(--sh-gold);font-family:var(--serif);font-size:24px;font-weight:900}
.score-badge-lg{width:120px;height:120px;font-size:36px;border-width:5px}
.room-code{display:inline-flex;align-items:center;gap:8px;padding:8px 16px;background:var(--cream-deep);border:1px dashed var(--gold);border-radius:var(--r-md);font-family:'Courier New',monospace;font-size:14px;font-weight:600;letter-spacing:.1em}

/* ── Mode Cards ── */
.mode-card{padding:20px;border-radius:var(--r-lg);border:2px solid var(--ch10);text-align:center;cursor:pointer;transition:all .25s}
.mode-card:hover{border-color:var(--gold);background:var(--gold-bg)}
.mode-card.selected{border-color:var(--red);background:var(--red-bg);box-shadow:0 0 0 3px rgba(197,48,48,.1)}
.mode-card-icon{width:40px;height:40px;margin:0 auto 12px;color:var(--gold)}
.mode-card.selected .mode-card-icon{color:var(--red)}

/* ── Option Cards ── */
.option-card{padding:16px;border:2px solid var(--ch10);border-radius:var(--r-lg);cursor:pointer;transition:all .25s;display:flex;align-items:center;gap:12px}
.option-card:hover:not(.disabled){border-color:var(--gold);background:var(--gold-bg);transform:translateX(4px)}
.option-card.correct{border-color:var(--ok);background:var(--ok-bg)}
.option-card.wrong{border-color:var(--no);background:var(--no-bg)}
.option-card.disabled{cursor:default;opacity:.7}
.opt-label{flex-shrink:0;width:32px;height:32px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-weight:700;font-size:14px;background:var(--cream-deep)}
.option-card.correct .opt-label{background:var(--ok);color:var(--white)}
.option-card.wrong .opt-label{background:var(--no);color:var(--white)}

/* ── Level Pills ── */
.pill{display:inline-flex;align-items:center;gap:4px;padding:2px 12px;border-radius:var(--r-2xl);font-size:12px;font-weight:600}
.pill-nb{background:var(--teal-bg);color:var(--teal)}.pill-th{background:var(--sky-bg);color:var(--sky)}
.pill-vd{background:var(--gold-bg);color:var(--gold-dk)}.pill-vdc{background:var(--red-bg);color:var(--red)}

/* ── Progress ── */
.progress{height:8px;background:var(--ch10);border-radius:4px;overflow:hidden}
.progress-fill{height:100%;background:linear-gradient(90deg,var(--gold),var(--red));border-radius:4px;transition:width .5s var(--ease)}

/* ── Drag Items ── */
.drag-zone{min-height:60px;border:2px dashed var(--ch10);border-radius:var(--r-lg);padding:16px;transition:all .15s}
.drag-zone.active{border-color:var(--gold);background:var(--gold-bg)}
.drag-item{padding:12px 16px;background:var(--white);border:1px solid var(--ch10);border-radius:var(--r-md);cursor:grab;font-size:14px;margin-bottom:8px;transition:all .15s;user-select:none}
.drag-item:active{cursor:grabbing}.drag-item:hover{border-color:var(--gold);box-shadow:var(--sh-sm)}
.drag-item.matched{background:var(--ok-bg);border-color:var(--ok)}

/* ── Seal Stamp ── */
.seal{display:inline-flex;align-items:center;justify-content:center;width:64px;height:64px;border:3px solid var(--red);border-radius:4px;transform:rotate(-8deg);font-family:var(--serif);font-weight:900;font-size:18px;color:var(--red);opacity:.8;position:relative}
.seal::after{content:'';position:absolute;inset:2px;border:1px solid var(--red);border-radius:2px;opacity:.4}

/* ── Hamburger (mobile) ── */
.hamburger{display:none;width:44px;height:44px;border:none;background:transparent;cursor:pointer;padding:8px;flex-shrink:0}
.hamburger span{display:block;width:24px;height:2px;background:var(--ch);margin:5px auto;border-radius:2px;transition:all .3s var(--ease)}
.hamburger.active span:nth-child(1){transform:rotate(45deg) translate(5px,5px)}
.hamburger.active span:nth-child(2){opacity:0}
.hamburger.active span:nth-child(3){transform:rotate(-45deg) translate(5px,-5px)}
.sidebar-backdrop{display:none;position:fixed;inset:0;background:rgba(45,42,38,.5);backdrop-filter:blur(2px);z-index:99;opacity:0;transition:opacity .3s}
.sidebar-backdrop.visible{display:block;opacity:1}

/* ── Tabs (scrollable) ── */
.tabs{display:flex;gap:4px;border-bottom:2px solid var(--ch10);margin-bottom:24px;overflow-x:auto;-webkit-overflow-scrolling:touch;scrollbar-width:none}
.tabs::-webkit-scrollbar{display:none}
.tab-btn{display:flex;align-items:center;gap:6px;padding:10px 16px;border:none;background:transparent;color:var(--ch50);font-family:var(--sans);font-size:13px;font-weight:500;cursor:pointer;border-bottom:2px solid transparent;margin-bottom:-2px;transition:all .15s;white-space:nowrap;flex-shrink:0;min-height:44px}
.tab-btn svg{width:16px;height:16px}
.tab-btn:hover{color:var(--ch)}
.tab-btn.active{color:var(--red);border-bottom-color:var(--red);font-weight:600}
.tab-count{font-size:11px;background:var(--ch10);color:var(--ch50);padding:1px 6px;border-radius:10px;margin-left:4px}
.tab-btn.active .tab-count{background:var(--red-bg);color:var(--red)}

/* ── Filter Bar ── */
.filter-bar{display:flex;gap:8px;margin-bottom:20px;flex-wrap:wrap;align-items:center}
.filter-bar .form-select,.filter-bar .form-input{max-width:200px;padding:8px 12px;font-size:13px;min-height:40px}

/* ═══ LAYOUT ═══ */
#app{min-height:100vh;position:relative;z-index:1}
.layout-t{display:flex;min-height:100vh}
/* Sidebar */
.sidebar{width:var(--sidebar-w);background:var(--ch);color:var(--white);display:flex;flex-direction:column;position:fixed;top:0;left:0;height:100vh;z-index:100;transition:transform .4s var(--ease)}
.sidebar-head{padding:24px 20px;border-bottom:1px solid rgba(255,255,255,.08)}
.sidebar-logo{font-family:var(--serif);font-size:24px;font-weight:900;background:linear-gradient(135deg,var(--gold-lt),var(--red-lt));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;letter-spacing:.05em}
.sidebar-sub{font-size:12px;color:rgba(255,255,255,.4);margin-top:4px}
.sidebar-nav{flex:1;padding:16px 12px;display:flex;flex-direction:column;gap:4px;overflow-y:auto}
.sidebar-link{display:flex;align-items:center;gap:12px;padding:10px 16px;border-radius:var(--r-md);color:rgba(255,255,255,.6);font-size:14px;font-weight:500;transition:all .15s;cursor:pointer;min-height:44px}
.sidebar-link svg{width:18px;height:18px;flex-shrink:0}
.sidebar-link:hover{background:rgba(255,255,255,.08);color:var(--white)}
.sidebar-link.active{background:rgba(212,168,67,.15);color:var(--gold-lt)}
.sidebar-sep{margin-top:20px;padding-top:16px;border-top:1px solid rgba(255,255,255,.06)}
.sidebar-sep-title{font-size:11px;color:rgba(255,255,255,.3);text-transform:uppercase;letter-spacing:.08em;padding:0 16px;margin-bottom:8px}
.sidebar-footer{padding:16px 20px;border-top:1px solid rgba(255,255,255,.06);display:flex;align-items:center;gap:12px}
.sidebar-avatar{width:36px;height:36px;border-radius:50%;background:linear-gradient(135deg,var(--red),var(--gold));display:flex;align-items:center;justify-content:center;font-weight:700;font-size:14px}
/* Main */
.main{flex:1;margin-left:var(--sidebar-w);min-height:100vh}
.content-header{padding:24px 32px;border-bottom:1px solid var(--ch10);background:var(--white);display:flex;align-items:center;justify-content:space-between;position:sticky;top:0;z-index:50;gap:12px}
.content-title{font-size:24px;font-weight:700}
.content-sub{font-size:14px;color:var(--ch50);margin-top:4px}
.content-body{padding:32px;max-width:1200px}
.stats-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:20px;margin-bottom:32px}
.stat-card{background:var(--white);border-radius:var(--r-lg);padding:20px;box-shadow:var(--sh-sm);display:flex;align-items:flex-start;gap:16px}
.stat-icon{width:44px;height:44px;border-radius:var(--r-md);display:flex;align-items:center;justify-content:center;flex-shrink:0}
.stat-icon svg{width:22px;height:22px}
.stat-icon-red{background:var(--red-bg);color:var(--red)}.stat-icon-gold{background:var(--gold-bg);color:var(--gold)}
.stat-icon-teal{background:var(--teal-bg);color:var(--teal)}.stat-icon-sky{background:var(--sky-bg);color:var(--sky)}
.stat-val{font-size:24px;font-weight:700;font-family:var(--serif);margin-bottom:4px}
.stat-lbl{font-size:12px;color:var(--ch50)}
.rooms-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(340px,1fr));gap:20px}
/* Student layout */
.layout-s{min-height:100vh;display:flex;flex-direction:column}
.s-topbar{padding:12px 20px;background:var(--white);border-bottom:1px solid var(--ch10);display:flex;align-items:center;justify-content:space-between;min-height:52px}
.s-logo{font-family:var(--serif);font-size:20px;font-weight:900;color:var(--red)}
.s-content{flex:1;display:flex;align-items:center;justify-content:center;padding:32px}
.s-center{width:100%;max-width:500px}
.s-wide{width:100%;max-width:800px}
.s-full{width:100%;max-width:1000px}
.quiz-layout{flex:1;display:flex;flex-direction:column;padding:24px;max-width:800px;margin:0 auto;width:100%}
.quiz-q{font-family:var(--serif);font-size:20px;font-weight:600;line-height:1.75;margin-bottom:24px}
.quiz-opts{display:flex;flex-direction:column;gap:12px}
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:32px}
/* Empty state */
.empty-state{text-align:center;padding:48px 24px;color:var(--ch50)}
.empty-state-icon{font-size:48px;margin-bottom:16px;color:var(--ch30)}

/* ═══ RESPONSIVE ═══ */
@media(max-width:1024px){
  .rooms-grid{grid-template-columns:1fr}
  .two-col{grid-template-columns:1fr}
  .mode-card-icon{width:32px;height:32px}
}
@media(max-width:768px){
  /* Sidebar → overlay */
  .sidebar{transform:translateX(-100%)}
  .sidebar.open{transform:translateX(0)}
  .main{margin-left:0}
  /* Hamburger visible */
  .hamburger{display:flex;align-items:center;justify-content:center}
  /* Header */
  .content-header{padding:12px 16px;flex-wrap:wrap}
  .content-title{font-size:18px}
  .content-body{padding:16px}
  /* Stats */
  .stats-grid{grid-template-columns:repeat(2,1fr);gap:12px}
  .stat-card{padding:14px;gap:12px}
  .stat-val{font-size:20px}
  .stat-icon{width:36px;height:36px}
  .stat-icon svg{width:18px;height:18px}
  /* Rooms grid */
  .rooms-grid{grid-template-columns:1fr;gap:12px}
  /* Card */
  .card{padding:16px}
  /* Table → scroll */
  .table th,.table td{padding:8px 12px;font-size:12px}
  /* Tabs: scroll horizontal */
  .tabs{gap:0;padding:0 16px}
  .tab-btn{padding:10px 12px;font-size:12px}
  /* Forms */
  .form-input,.form-select,.form-textarea{padding:10px 12px;font-size:16px /* prevent iOS zoom */}
  /* Quiz */
  .s-content{padding:16px}
  .quiz-q{font-size:17px}
  .quiz-layout{padding:16px}
  .option-card{padding:12px;gap:10px}
  .opt-label{width:28px;height:28px;font-size:12px}
  /* Mode grid */
  #modeGrid{grid-template-columns:repeat(2,1fr) !important}
  .mode-card{padding:12px}
  .mode-card-icon{width:28px;height:28px;margin-bottom:8px}
  /* AI panel */
  .ai-panel{padding:14px}
  /* Score badge */
  .score-badge{width:64px;height:64px;font-size:20px;border-width:3px}
  .score-badge-lg{width:90px;height:90px;font-size:28px;border-width:4px}
  /* Two-col */
  .two-col{gap:16px}
  /* Đối Kháng: stack leaderboard below */
  .dk-layout{flex-direction:column !important}
  .dk-sidebar{width:100% !important;border-left:none !important;border-top:1px solid var(--ch10) !important;max-height:200px;overflow-y:auto}
  /* Filter bar */
  .filter-bar{gap:6px}
  .filter-bar .form-select,.filter-bar .form-input{max-width:100%;flex:1;min-width:120px}
}
@media(max-width:480px){
  .stats-grid{grid-template-columns:1fr}
  .content-header{flex-direction:column;align-items:flex-start;gap:8px}
  .content-header .btn{width:100%;justify-content:center}
  .tab-btn{padding:8px 10px;font-size:11px}
  .room-code{font-size:12px;padding:6px 10px}
  .seal{width:48px;height:48px;font-size:14px}
  .badge{font-size:11px;padding:2px 8px}
  .btn-lg{padding:12px 24px;font-size:14px}
  .mode-card{padding:10px}
}

/* ── Connect Mode (Nối Sự Kiện) ── */
.drag-item{background:var(--white);border:2px solid var(--ch10);border-radius:8px;padding:12px 16px;font-size:14px;line-height:1.5;transition:all .2s ease;cursor:pointer}
.drag-item:hover:not(.matched){border-color:var(--gold);background:var(--gold-bg)}
.drag-item.selected{border-color:var(--gold);background:var(--gold-bg);box-shadow:0 0 0 3px rgba(217,169,56,.25);font-weight:600}
.drag-item.matched{border-color:var(--ok);background:var(--ok-bg);cursor:default}
.drag-zone{border-radius:8px;transition:all .2s ease}
.drag-zone:hover:not(.wrong) .drag-item:not(.matched){border-color:var(--teal)}
.drag-zone.wrong{animation:shake .4s ease}
.drag-zone.wrong .drag-item{border-color:var(--no)!important;background:var(--no-bg,#fef2f2)!important}
@keyframes shake{0%,100%{transform:translateX(0)}20%,60%{transform:translateX(-6px)}40%,80%{transform:translateX(6px)}}