:root{
  --navy:#0F172A;--navy2:#1E293B;--violet:#7C3AED;--violet2:#6D28D9;
  --amber:#F59E0B;--mint:#10B981;--coral:#EF4444;--sky:#38BDF8;--pink:#EC4899;
  --gray400:#94A3B8;--gray600:#475569;
}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
body{font-family:'Nunito',sans-serif;background:var(--navy);color:#fff;min-height:100vh;overflow-x:hidden}
body::before{
  content:'';position:fixed;inset:0;pointer-events:none;z-index:0;
  background-image:
    radial-gradient(1.5px 1.5px at 8% 12%,rgba(255,255,255,.55) 0,transparent 100%),
    radial-gradient(1px 1px at 25% 65%,rgba(255,255,255,.35) 0,transparent 100%),
    radial-gradient(2px 2px at 40% 28%,rgba(255,255,255,.5) 0,transparent 100%),
    radial-gradient(1px 1px at 60% 80%,rgba(255,255,255,.3) 0,transparent 100%),
    radial-gradient(1.5px 1.5px at 75% 18%,rgba(255,255,255,.5) 0,transparent 100%),
    radial-gradient(1px 1px at 88% 55%,rgba(255,255,255,.4) 0,transparent 100%),
    radial-gradient(2px 2px at 92% 85%,rgba(255,255,255,.45) 0,transparent 100%),
    radial-gradient(1px 1px at 15% 90%,rgba(255,255,255,.3) 0,transparent 100%);
}
#app{position:relative;z-index:1}
.screen{display:none;min-height:100vh;flex-direction:column}
.screen.active{display:flex}
h1,h2,h3,.display{font-family:'Fredoka One',cursive;letter-spacing:.02em}
.card{background:rgba(30,41,59,.88);border:1.5px solid rgba(124,58,237,.25);border-radius:22px;backdrop-filter:blur(14px);box-shadow:0 4px 24px rgba(15,23,42,.25)}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;font-weight:800;font-size:16px;border:none;border-radius:50px;cursor:pointer;padding:13px 26px;transition:all .18s;-webkit-tap-highlight-color:transparent}
.btn:active{transform:scale(.96)}
.btn-primary{background:var(--violet);color:#fff;box-shadow:0 4px 14px rgba(124,58,237,.4)}
.btn-primary:hover{background:var(--violet2);transform:translateY(-1px)}
.btn-amber{background:var(--amber);color:var(--navy);box-shadow:0 4px 14px rgba(245,158,11,.4)}
.btn-mint{background:var(--mint);color:#fff;box-shadow:0 4px 14px rgba(16,185,129,.35)}
.btn-ghost{background:rgba(255,255,255,.1);color:#fff;border:1.5px solid rgba(255,255,255,.2)}
.btn-ghost:hover{background:rgba(255,255,255,.18)}
.btn-sm{padding:7px 16px;font-size:13px}
.btn-lg{padding:16px 34px;font-size:18px}
.btn-block{width:100%}
.btn:disabled{opacity:.5;cursor:not-allowed}

/* TOPBAR */
.topbar{display:flex;align-items:center;justify-content:space-between;padding:12px 18px;background:rgba(15,23,42,.78);border-bottom:1px solid rgba(124,58,237,.22);backdrop-filter:blur(14px);position:sticky;top:0;z-index:100;gap:8px}
.topbar-logo{font-family:'Fredoka One';font-size:21px;color:var(--amber);white-space:nowrap;cursor:pointer;display:flex;align-items:center;gap:8px}
.topbar-right{display:flex;align-items:center;gap:7px}
.xp-pill{display:flex;align-items:center;gap:5px;background:rgba(245,158,11,.15);border:1px solid rgba(245,158,11,.3);border-radius:20px;padding:5px 10px;font-size:13px;font-weight:800;color:var(--amber);white-space:nowrap}
.icon-btn{width:34px;height:34px;border-radius:50%;border:none;cursor:pointer;background:rgba(255,255,255,.08);font-size:16px;display:flex;align-items:center;justify-content:center;transition:all .15s}
.icon-btn:hover{background:rgba(255,255,255,.16);transform:scale(1.08)}
.icon-btn.off{opacity:.4}

/* GRADE SELECTOR (landing) */
#screen-grade{align-items:center;justify-content:center;padding:24px 16px;min-height:100vh}
.grade-wrap{max-width:640px;width:100%;text-align:center}
.brand-hero{margin-bottom:28px}
.brand-hero .planet{display:block;animation:float 3s ease-in-out infinite}
.logo-abacus{display:inline-block;width:64px;height:53px;margin:0 auto}
.logo-abacus svg{width:100%;height:100%;display:block}
.logo-abacus-sm{width:26px;height:22px;animation:none}
.brand-hero h1{font-size:42px;color:var(--amber);margin-top:6px}
.brand-hero p{color:var(--gray400);font-size:15px;font-weight:700;margin-top:4px}
.grades-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:13px}
.grade-card{border-radius:20px;padding:20px 10px;cursor:pointer;text-align:center;border:2px solid rgba(255,255,255,.1);background:rgba(255,255,255,.05);transition:all .2s}
.grade-card:hover{transform:translateY(-5px) scale(1.04);border-color:var(--violet);background:rgba(124,58,237,.18)}
.grade-icon{font-size:34px;margin-bottom:7px}
.grade-label{font-family:'Fredoka One';font-size:15px;margin-bottom:2px}
.grade-age{font-size:11px;color:var(--gray400);font-weight:700}
.name-row{display:flex;gap:10px;max-width:380px;margin:0 auto 10px}
.name-error{color:var(--coral);font-size:13px;font-weight:700;margin-bottom:14px;max-width:380px;margin-left:auto;margin-right:auto}
.input.shake-err{animation:shake .4s ease;border-color:var(--coral)!important}
.logged-in-chip{display:inline-flex;align-items:center;gap:6px;background:rgba(16,185,129,.13);border:1.5px solid rgba(16,185,129,.3);border-radius:20px;padding:7px 16px;font-size:13px;font-weight:700;color:#fff}
.logged-in-chip a{color:var(--violet);text-decoration:underline;cursor:pointer}
.avatar-row{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;max-width:380px;margin:0 auto 18px}
.input{width:100%;padding:13px 18px;font-size:16px;font-weight:700;background:rgba(255,255,255,.07);border:2px solid rgba(255,255,255,.15);border-radius:12px;color:#fff;outline:none}
.input::placeholder{color:rgba(255,255,255,.35)}
.input:focus{border-color:var(--violet);background:rgba(124,58,237,.1)}
.avatar-row{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;max-width:380px;margin:0 auto 22px}
.avatar-opt{font-size:24px;width:42px;height:42px;display:flex;align-items:center;justify-content:center;border-radius:11px;border:2px solid rgba(255,255,255,.15);cursor:pointer;transition:all .15s}
.avatar-opt.sel{border-color:var(--violet);background:rgba(124,58,237,.25)}

/* HOME */
.home-hero{padding:22px 20px 14px;text-align:center}
.home-hero h2{font-size:23px}
.home-hero p{color:var(--gray400);font-size:14px;margin-top:5px}
.mode-chip{display:inline-flex;align-items:center;gap:6px;background:rgba(124,58,237,.15);border:1.5px solid rgba(124,58,237,.3);border-radius:20px;padding:6px 14px;font-size:13px;font-weight:800;color:var(--violet);cursor:pointer;margin-top:9px;transition:all .15s}
.mode-chip:hover{background:rgba(124,58,237,.25)}
.mode-chip.self-mode{background:rgba(16,185,129,.13);border-color:rgba(16,185,129,.3);color:var(--mint)}
.streak-bar{display:flex;align-items:center;justify-content:center;gap:9px;padding:11px 18px;flex-wrap:wrap}
.stat-chip{display:flex;align-items:center;gap:6px;background:rgba(255,255,255,.07);border:1px solid rgba(255,255,255,.1);border-radius:20px;padding:6px 12px;font-size:12.5px;font-weight:700}
.section-title{padding:0 18px;margin-bottom:13px;font-family:'Fredoka One';font-size:21px}
.topics-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:12px;padding:0 18px 22px}
.topic-card{border-radius:19px;padding:17px 13px;cursor:pointer;transition:all .2s;position:relative;display:flex;flex-direction:column;align-items:center;gap:8px;text-align:center;min-height:135px;justify-content:center;border:2px solid transparent}
.topic-card:hover{transform:translateY(-4px) scale(1.03);box-shadow:0 12px 30px rgba(0,0,0,.3)}
.topic-icon{font-size:34px}
.topic-name{font-family:'Fredoka One';font-size:14px;line-height:1.2}
.topic-progress{font-size:10.5px;font-weight:700;opacity:.85}
.topic-badge{position:absolute;top:8px;right:8px;font-size:10px;font-weight:800;padding:2px 7px;border-radius:10px;background:rgba(255,255,255,.22);color:#fff}
.progress-ring{width:100%;height:4px;background:rgba(255,255,255,.22);border-radius:4px;margin-top:3px;overflow:hidden}
.progress-ring-fill{height:100%;border-radius:4px;background:rgba(255,255,255,.85);transition:width .4s}
.topic-c1{background:linear-gradient(135deg,#7C3AED,#4F46E5);color:#fff}
.topic-c2{background:linear-gradient(135deg,#059669,#10B981);color:#fff}
.topic-c3{background:linear-gradient(135deg,#D97706,#F59E0B);color:#fff}
.topic-c4{background:linear-gradient(135deg,#DC2626,#EF4444);color:#fff}
.topic-c5{background:linear-gradient(135deg,#0369A1,#38BDF8);color:#fff}
.topic-c6{background:linear-gradient(135deg,#7E22CE,#EC4899);color:#fff}

/* TOPIC DETAIL */
.topic-detail-header{padding:15px 18px;display:flex;align-items:center;gap:11px}
.topic-detail-icon{width:54px;height:54px;border-radius:15px;display:flex;align-items:center;justify-content:center;font-size:28px;flex-shrink:0}
.topic-detail-info h2{font-size:20px;font-family:'Fredoka One'}
.topic-detail-info p{font-size:12.5px;color:var(--gray400)}
.back-btn{background:none;border:none;color:var(--gray400);font-size:21px;cursor:pointer;padding:4px 8px;flex-shrink:0}
.back-btn:hover{color:#fff}
.desc-box{margin:0 18px 14px;background:rgba(124,58,237,.1);border:1.5px solid rgba(124,58,237,.25);border-radius:15px;padding:15px}
.desc-box h3{font-family:'Fredoka One';font-size:15px;color:var(--violet);margin-bottom:6px}
.desc-box p{font-size:13.5px;color:var(--gray400);line-height:1.6}
.example-box{margin:0 18px 14px;background:rgba(245,158,11,.08);border:1.5px solid rgba(245,158,11,.25);border-radius:15px;padding:15px}
.example-box h3{font-family:'Fredoka One';font-size:15px;color:var(--amber);margin-bottom:8px}
.example-item{font-size:13.5px;color:var(--gray400);margin-bottom:5px}
.example-item strong{color:#fff}
.mode-select{padding:0 18px 22px}
.mode-select h3{font-family:'Fredoka One';font-size:17px;margin-bottom:12px}
.mode-cards{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.mode-card{padding:15px 12px;border-radius:15px;cursor:pointer;text-align:center;border:2px solid rgba(255,255,255,.1);background:rgba(255,255,255,.05);transition:all .18s}
.mode-card:hover{border-color:var(--violet);background:rgba(124,58,237,.12);transform:translateY(-2px)}
.mode-card .mode-icon{font-size:26px;margin-bottom:6px}
.mode-card h4{font-family:'Fredoka One';font-size:14px;margin-bottom:2px}
.mode-card p{font-size:11px;color:var(--gray400)}

/* QUIZ */
.quiz-topbar{display:flex;align-items:center;justify-content:space-between;padding:12px 16px;background:rgba(15,23,42,.85);border-bottom:1px solid rgba(124,58,237,.2);position:sticky;top:0;z-index:10;gap:9px}
.quiz-progress-track{flex:1;margin:0 10px;height:7px;background:rgba(255,255,255,.12);border-radius:8px;overflow:hidden}
.quiz-progress-fill{height:100%;background:linear-gradient(90deg,var(--violet),var(--sky));border-radius:8px;transition:width .35s}
.quiz-num{font-size:12.5px;font-weight:800;color:var(--gray400);white-space:nowrap}
.timer-pill{display:flex;align-items:center;gap:4px;background:rgba(239,68,68,.15);border:1px solid rgba(239,68,68,.3);border-radius:20px;padding:4px 11px;font-size:13px;font-weight:800;color:var(--coral);white-space:nowrap}
.timer-pill.warning{animation:pulse 1s infinite}
.quiz-body{padding:18px 16px;max-width:680px;margin:0 auto;width:100%}
.question-card{padding:22px 19px;margin-bottom:16px;border-radius:19px}
.q-topic-badge{display:inline-block;font-size:11.5px;font-weight:800;padding:3px 10px;border-radius:20px;background:rgba(124,58,237,.2);color:var(--violet);margin-bottom:10px}
.q-text{font-size:18px;font-weight:700;line-height:1.5;color:#fff}
.q-svg{width:100%;max-height:95px;margin:11px 0 3px;display:block}

.answer-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-bottom:14px}
.answer-btn{padding:14px 12px;border-radius:15px;border:2px solid rgba(255,255,255,.12);background:rgba(255,255,255,.05);color:#fff;font-size:14.5px;font-weight:700;cursor:pointer;transition:all .15s;text-align:left;display:flex;align-items:center;gap:8px}
.answer-btn:hover:not(:disabled){border-color:var(--violet);background:rgba(124,58,237,.18);transform:translateY(-2px)}
.answer-letter{width:25px;height:25px;border-radius:50%;background:rgba(255,255,255,.1);display:flex;align-items:center;justify-content:center;font-size:11.5px;font-weight:800;flex-shrink:0}
.answer-btn.selected{border-color:var(--violet);background:rgba(124,58,237,.25)}
.answer-btn.correct{border-color:var(--mint)!important;background:rgba(16,185,129,.2)!important;animation:correctPop .4s ease}
.answer-btn.wrong{border-color:var(--coral)!important;background:rgba(239,68,68,.18)!important}
.answer-btn.reveal{border-color:var(--mint)!important;background:rgba(16,185,129,.1)!important}
.answer-btn:disabled{cursor:default}
.answer-btn.wrong-shake{animation:shake .4s ease}
.fill-input-wrap{margin-bottom:14px}
.fill-input{width:100%;padding:15px 18px;font-size:21px;font-weight:800;text-align:center;font-family:'Fredoka One';background:rgba(255,255,255,.06);border:2px solid rgba(255,255,255,.15);border-radius:15px;color:#fff;outline:none}
.fill-input:focus{border-color:var(--violet)}
.fill-input.correct{border-color:var(--mint)!important;background:rgba(16,185,129,.12)!important}
.fill-input.wrong{border-color:var(--coral)!important;background:rgba(239,68,68,.1)!important;animation:shake .35s ease}
.quiz-actions{display:flex;gap:9px;flex-wrap:wrap;align-items:center}
.feedback-box{padding:14px 16px;border-radius:15px;margin-bottom:13px;display:none}
.feedback-box.show{display:flex;gap:10px;align-items:flex-start}
.correct-fb{background:rgba(16,185,129,.15);border:1.5px solid rgba(16,185,129,.35)}
.wrong-fb{background:rgba(239,68,68,.12);border:1.5px solid rgba(239,68,68,.3)}
.feedback-icon{font-size:21px;flex-shrink:0;margin-top:1px}
.feedback-text h4{font-weight:800;font-size:14.5px;margin-bottom:3px}
.feedback-text p{font-size:12.5px;color:var(--gray400);line-height:1.5}
.correct-fb .feedback-text h4{color:var(--mint)}
.wrong-fb .feedback-text h4{color:var(--coral)}
.hint-box{padding:12px 14px;border-radius:13px;margin-bottom:12px;background:rgba(245,158,11,.1);border:1.5px solid rgba(245,158,11,.25);display:none}
.hint-box.show{display:block}
.hint-label{font-family:'Fredoka One';font-size:13px;color:var(--amber);margin-bottom:3px}
.hint-box p{font-size:13px;color:#FEF3C7;line-height:1.5}

/* RESULT */
#screen-result{align-items:center;justify-content:center;padding:22px}
.result-box{max-width:440px;width:100%;padding:32px 26px;text-align:center}
.result-emoji{font-size:64px;margin-bottom:9px;animation:bounceIn .6s ease}
.result-grade{font-family:'Fredoka One';font-size:50px;margin-bottom:4px}
.grade-S{color:var(--amber)}.grade-A{color:var(--mint)}.grade-B{color:var(--sky)}.grade-C{color:var(--violet)}.grade-D{color:var(--coral)}
.result-msg{font-size:14px;color:var(--gray400);margin-bottom:18px}
.result-stats{display:grid;grid-template-columns:1fr 1fr 1fr;gap:9px;margin-bottom:20px}
.result-stat{padding:13px 6px;border-radius:14px;background:rgba(255,255,255,.06)}
.rs-num{font-family:'Fredoka One';font-size:24px}
.rs-lbl{font-size:10.5px;font-weight:700;color:var(--gray400);margin-top:2px}
.xp-gained{display:flex;align-items:center;justify-content:center;gap:7px;padding:12px;border-radius:13px;margin-bottom:16px;background:rgba(245,158,11,.12);border:1.5px solid rgba(245,158,11,.3);font-family:'Fredoka One';font-size:18px;color:var(--amber)}
.result-btns{display:flex;flex-direction:column;gap:8px}

/* LEADERBOARD */
.lb-header{padding:20px 18px 12px}
.lb-header h2{font-family:'Fredoka One';font-size:24px}
.podium{display:flex;align-items:flex-end;justify-content:center;gap:7px;padding:0 18px 18px}
.podium-spot{flex:1;max-width:105px;text-align:center}
.podium-av{font-size:28px;margin-bottom:4px}
.podium-name{font-size:11.5px;font-weight:800;margin-bottom:4px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.podium-block{border-radius:11px 11px 0 0;display:flex;flex-direction:column;align-items:center;padding-top:8px}
.p1{height:80px;background:linear-gradient(180deg,rgba(245,158,11,.5),rgba(245,158,11,.1));border:1.5px solid rgba(245,158,11,.4)}
.p2{height:58px;background:linear-gradient(180deg,rgba(148,163,184,.35),rgba(148,163,184,.08));border:1.5px solid rgba(148,163,184,.3)}
.p3{height:44px;background:linear-gradient(180deg,rgba(180,83,9,.35),rgba(180,83,9,.08));border:1.5px solid rgba(180,83,9,.3)}
.podium-rank{font-family:'Fredoka One';font-size:18px}
.podium-pts{font-size:10.5px;font-weight:700;color:var(--gray400)}
.lb-list{padding:0 18px 36px}
.lb-row{display:flex;align-items:center;gap:11px;padding:12px 15px;border-radius:14px;margin-bottom:7px;background:rgba(255,255,255,.04);border:1.5px solid rgba(255,255,255,.06)}
.lb-row.me{background:rgba(124,58,237,.15);border-color:rgba(124,58,237,.4)}
.lb-row.top1{background:rgba(245,158,11,.1);border-color:rgba(245,158,11,.3)}
.lb-rank{font-family:'Fredoka One';font-size:18px;width:32px;text-align:center}
.lb-av{width:34px;height:34px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:16px;flex-shrink:0}
.lb-name{flex:1;font-weight:800;font-size:13.5px;display:flex;align-items:center;gap:5px;flex-wrap:wrap}
.lb-score{font-family:'Fredoka One';font-size:16px;color:var(--amber)}
.lb-badge{font-size:9.5px;font-weight:700;padding:2px 6px;border-radius:9px;background:rgba(124,58,237,.25);color:var(--violet)}
.lb-grade-badge{font-size:9.5px;font-weight:700;padding:2px 6px;border-radius:9px;background:rgba(245,158,11,.2);color:var(--amber)}

/* PROGRESS */
.progress-header{padding:20px 18px 12px}
.progress-header h2{font-family:'Fredoka One';font-size:24px}
.chart-wrap{padding:0 18px 16px}
.chart-card{padding:16px;border-radius:17px;background:rgba(255,255,255,.04);border:1.5px solid rgba(255,255,255,.08)}
.chart-title{font-family:'Fredoka One';font-size:14px;color:var(--gray400);margin-bottom:13px}
.bar-chart{display:flex;align-items:flex-end;gap:6px;height:100px}
.bar-col{flex:1;display:flex;flex-direction:column;align-items:center;gap:3px;height:100%;justify-content:flex-end}
.bar-fill{width:100%;border-radius:6px 6px 0 0;transition:height .6s;min-height:3px}
.bar-lbl{font-size:9.5px;font-weight:700;color:var(--gray400)}
.bar-val{font-size:10.5px;font-weight:800;color:#fff}
.topic-progress-list{padding:0 18px}
.tprog-row{display:flex;align-items:center;gap:10px;padding:10px 0;border-bottom:1px solid rgba(255,255,255,.06)}
.tprog-icon{font-size:19px;width:32px;text-align:center}
.tprog-info{flex:1}
.tprog-name{font-weight:800;font-size:12.5px;margin-bottom:4px}
.tprog-track{height:6px;background:rgba(255,255,255,.1);border-radius:6px;overflow:hidden}
.tprog-fill{height:100%;border-radius:6px;background:linear-gradient(90deg,var(--violet),var(--sky));transition:width .4s}
.tprog-pct{font-size:12.5px;font-weight:800;color:var(--amber);width:36px;text-align:right}

/* TOAST */
.toast{position:fixed;bottom:20px;left:50%;transform:translateX(-50%) translateY(80px);background:var(--navy2);border:1.5px solid rgba(255,255,255,.15);border-radius:20px;padding:10px 18px;font-size:13.5px;font-weight:700;color:#fff;z-index:300;white-space:nowrap;max-width:90vw;transition:transform .3s,opacity .3s;opacity:0}
.toast.show{transform:translateX(-50%) translateY(0);opacity:1}

@keyframes float{0%,100%{transform:translateY(0)}50%{transform:translateY(-9px)}}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:.55}}
@keyframes correctPop{0%{transform:scale(1)}50%{transform:scale(1.05)}100%{transform:scale(1)}}
@keyframes bounceIn{0%{transform:scale(.5);opacity:0}70%{transform:scale(1.1)}100%{transform:scale(1);opacity:1}}
@keyframes starPop{0%{transform:scale(0) rotate(-20deg)}60%{transform:scale(1.35) rotate(5deg)}100%{transform:scale(1) rotate(0)}}
@keyframes shake{0%,100%{transform:translateX(0)}20%{transform:translateX(-7px)}40%{transform:translateX(7px)}60%{transform:translateX(-5px)}80%{transform:translateX(5px)}}
.confetti-piece{position:fixed;pointer-events:none;z-index:400;width:8px;height:8px;border-radius:2px;animation:confettiFall 1.6s ease forwards}
@keyframes confettiFall{0%{transform:translateY(-20px) rotate(0);opacity:1}100%{transform:translateY(100vh) rotate(720deg);opacity:0}}

.hidden{display:none!important}
.text-amber{color:var(--amber)}.text-mint{color:var(--mint)}.text-coral{color:var(--coral)}

@media(max-width:520px){
  .grades-grid{grid-template-columns:repeat(2,1fr)}
  .topics-grid{grid-template-columns:repeat(2,1fr);gap:9px;padding:0 13px 13px}
  .answer-grid{grid-template-columns:1fr}
  .mode-cards{grid-template-columns:1fr 1fr}
  .q-text{font-size:16px}
  .quiz-body{padding:13px 12px}
  .brand-hero h1{font-size:34px}
}