:root{--ink:#242338;--muted:#7b7b98;--bg:#f8f8ff;--primary:#6754e8;--shadow:0 16px 40px rgba(58,49,134,.12)}*{box-sizing:border-box}html,body{margin:0;min-height:100%;font-family:"PingFang SC","Microsoft YaHei",system-ui,sans-serif;color:var(--ink);background:linear-gradient(135deg,#f6f5ff,#fff8fb);-webkit-tap-highlight-color:transparent}body{display:flex;justify-content:center}.app-shell{width:100%;max-width:480px;min-height:100svh;position:relative;padding-bottom:86px;overflow:hidden}.screen{display:none;padding:22px 20px 24px;animation:fade-in .28s ease}.screen.is-active{display:block}@keyframes fade-in{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:translateY(0)}}.topbar,.practice-topbar{display:flex;align-items:center;justify-content:space-between}.brand-lockup{display:flex;align-items:center;gap:10px}.brand-mark{width:38px;height:38px;border-radius:13px;background:var(--primary);color:#fff;display:grid;place-items:center;font-size:22px;box-shadow:0 7px 17px 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1fr;gap:12px}.lesson-card{position:relative;text-align:left;display:flex;flex-direction:column;align-items:flex-start;min-height:146px;padding:16px 14px 12px;border:0;border-radius:20px;overflow:hidden;color:var(--ink);cursor:pointer;transition:transform .18s}.lesson-card:before{content:"";position:absolute;right:-15px;top:-20px;width:80px;height:80px;border-radius:50%;background:rgba(255,255,255,.26)}.lesson-card.coral{background:#ffe8e4}.lesson-card.purple{background:#eee8ff}.lesson-card.yellow{background:#fff3d7}.lesson-card.blue{background:#e4f1ff}.lesson-icon{font-size:27px;margin-bottom:9px}.lesson-title{font-weight:800;font-size:14px;letter-spacing:.2px}.lesson-subtitle{font-size:10px;color:#77758f;margin-top:3px}.lesson-stars{font-size:11px;color:#f4ad48;letter-spacing:1px;margin-top:auto}.achievement-card{display:flex;align-items:center;gap:13px;padding:16px;margin-top:25px;border-radius:20px;background:#fff;box-shadow:0 7px 23px rgba(66,59,133,.07)}.achievement-badge{width:45px;height:45px;border-radius:15px;background:#fff2d0;display:grid;place-items:center;font-size:25px}.achievement-card h3{font-family:"Arial Rounded MT Bold",system-ui;font-size:18px;margin:0}.achievement-card p:not(.eyebrow){font-size:10px;color:var(--muted);margin:0}.progress-ring{margin-left:auto;width:48px;height:48px;border-radius:50%;display:grid;place-items:center;background:conic-gradient(var(--primary) 60%,#ecebfa 0);position:relative}.progress-ring:before{content:"";position:absolute;inset:5px;border-radius:50%;background:#fff}.progress-ring span{z-index:1;font-size:10px;font-weight:800;color:var(--primary)}.bottom-nav{position:fixed;z-index:10;bottom:0;left:50%;width:min(480px,100%);transform:translateX(-50%);display:grid;grid-template-columns:repeat(4,1fr);padding:10px 15px max(10px,env(safe-area-inset-bottom));background:rgba(255,255,255,.92);backdrop-filter:blur(15px);border-top:1px solid #f0eff7}.nav-item{border:0;background:transparent;color:#a5a3bb;display:flex;flex-direction:column;align-items:center;gap:2px;font-family:inherit;cursor:pointer}.nav-item span{font-size:20px;line-height:23px}.nav-item small{font-size:10px}.nav-item.active{color:var(--primary);font-weight:800}.screen-practice{padding-top:18px}.practice-topbar{gap:11px}.back-button{box-shadow:none;background:transparent;font-size:28px;color:var(--ink);width:32px}.progress-track{height:8px;background:#e8e6f8;border-radius:20px;flex:1;overflow:hidden}.progress-track span{display:block;width:20%;height:100%;background:linear-gradient(90deg,#6754e8,#ab8cf2);border-radius:20px;transition:width .3s ease}.question-count{font-family:"Arial Rounded MT Bold",system-ui;font-weight:800;color:#8d8aa7;font-size:14px}.practice-intro{text-align:center;margin:43px 0 24px}.practice-intro h2{font-family:"Arial Rounded MT Bold",system-ui;font-size:31px;margin:0 0 5px}.practice-intro p:last-child{font-size:12px;color:var(--muted);margin:0}.question-card{position:relative;display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:218px;border-radius:26px;background:#fff;box-shadow:var(--shadow);overflow:hidden}.question-card:after{content:"";position:absolute;inset:auto -30px -75px;width:180px;height:130px;border:16px solid #f0edff;border-radius:50%}.question-decoration{position:absolute;right:26px;top:20px;color:#f4be4d;font-size:20px}.equation{font-family:"Arial Rounded MT Bold",system-ui;font-size:52px;font-weight:800;letter-spacing:2px;color:var(--primary)}.encouragement{color:#a5a2ba;font-size:12px;margin:9px 0 0}.answer-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-top:19px}.answer-button{border:2px solid #edeaf8;background:#fff;color:var(--ink);border-radius:17px;min-height:62px;font-family:"Arial Rounded MT Bold",system-ui;font-size:28px;font-weight:800;cursor:pointer;transition:all .2s}.answer-button:hover,.answer-button:focus-visible{border-color:#9b89f0;background:#f7f4ff}.answer-button.correct{background:#dff8eb;border-color:#66c997;color:#1e9c60}.answer-button.wrong{background:#ffe7e3;border-color:#ff8a77;color:#e85845}.answer-button:disabled{cursor:default}.feedback{height:35px;text-align:center;font-size:13px;font-weight:800;padding-top:12px;color:#43a873}.feedback.error{color:#e85845}.practice-footer{display:flex;justify-content:center;align-items:center;gap:9px;margin-top:20px;font-size:11px;color:var(--muted)}.practice-footer strong{color:var(--primary);font-size:16px}.mini-sparkle{color:#f4be4d;font-size:17px}.screen-result{text-align:center;padding-top:48px}.result-confetti{font-family:"Arial Rounded MT Bold",system-ui;font-size:27px;color:#fac64e;letter-spacing:6px;transform:rotate(-5deg);margin-bottom:17px}.result-icon{font-size:64px;filter:drop-shadow(0 7px 12px rgba(240,174,51,.27));animation:float 3.1s ease-in-out infinite}.screen-result h2{font-family:"Arial Rounded MT Bold",system-ui;font-size:36px;margin:8px 0 0}.result-subtitle{color:var(--muted);font-size:13px;margin:2px 0 22px}.result-score{background:#fff;border-radius:23px;padding:17px;box-shadow:var(--shadow)}.result-score strong{font-family:"Arial Rounded MT Bold",system-ui;font-size:47px;color:var(--primary);line-height:1}.result-score span{color:var(--muted);font-size:13px;margin-left:4px}.score-stars{color:#f4b94d;font-size:18px;letter-spacing:2px;margin-top:8px}.result-stats{display:grid;grid-template-columns:repeat(3,1fr);padding:18px 0 26px}.result-stats div{display:flex;flex-direction:column;gap:3px;border-right:1px solid #efeff7}.result-stats div:last-child{border:0}.result-stats strong{font-family:"Arial Rounded MT Bold",system-ui;font-size:23px;color:var(--ink)}.result-stats span{font-size:10px;color:var(--muted)}.wide{width:100%;background:var(--primary);color:#fff}.secondary-button{border:0;background:transparent;color:var(--muted);font-family:inherit;font-weight:700;font-size:13px;padding:15px;cursor:pointer}.toast{position:fixed;left:50%;bottom:92px;z-index:20;transform:translate(-50%,10px);opacity:0;pointer-events:none;background:#26243a;color:#fff;padding:11px 18px;border-radius:12px;font-size:12px;transition:.25s;white-space:nowrap}.toast.show{opacity:1;transform:translate(-50%,0)}@media(min-width:600px){body{padding:18px 0}.app-shell{box-shadow:0 0 50px rgba(74,63,142,.08);border-radius:26px;min-height:calc(100svh - 36px);background:var(--bg)}}

[hidden]{display:none!important}
.difficulty-control{display:flex;align-items:center;justify-content:space-between;gap:10px;margin:4px 0 8px;font-size:13px}
.difficulty-control select{font:inherit;font-size:16px;max-width:70%;min-height:44px;border:1px solid #ded8f7;border-radius:12px;padding:8px;background:#fff;color:#6754e8}
.round-note{font-size:11px;color:#73708a;margin:0 0 16px;line-height:1.7}
.equation{font-size:clamp(24px,8vw,38px);letter-spacing:0;overflow-wrap:anywhere;max-width:100%;text-align:center;position:relative;z-index:1}
.equation.word-question{font-size:clamp(21px,6vw,26px);line-height:1.5}
.question-card{padding:24px 14px;min-height:210px}.practice-intro{margin:26px 0 20px}
.shape-visual{display:flex;flex-wrap:wrap;justify-content:center;gap:12px;position:relative;z-index:1;margin:0 0 22px}.shape-visual:empty{display:none}
.math-shape{display:block;width:42px;height:42px;background:#9b78ee;flex-shrink:0}
.math-shape.triangle{clip-path:polygon(50% 0,100% 100%,0 100%);background:#ff9f5b}
.math-shape.rectangle{width:64px;height:36px;background:#60a9e6}
.math-shape.circle{border-radius:50%;background:#ffce63}
.answer-grid.four-options{grid-template-columns:repeat(2,1fr)}.answer-button{font-size:clamp(19px,5.5vw,28px);min-width:0;min-height:64px}
.explanation{font-size:14px;line-height:1.8;color:#6b6683;background:#f0edff;border-radius:14px;padding:14px;margin:10px 0 14px}.explanation:empty{display:none}
.feedback{height:auto;min-height:35px;line-height:1.7}.hint-button{display:block;margin:auto;min-height:44px}
.toast{white-space:normal;width:max-content;max-width:90%;text-align:center;line-height:1.7}
.lesson-stars{color:#78664d;font-size:11px}.nav-item{min-height:44px}.screen{padding-top:max(22px,env(safe-area-inset-top))}
@media(max-width:390px){.hero-illustration{right:-45px;top:80px;transform:scale(.7);opacity:.6}.hero-copy{max-width:100%}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}

.offline-panel{display:flex;align-items:center;justify-content:space-between;gap:8px;margin-top:18px;border-radius:12px;padding:8px 12px;background:#eeebfa}.offline-panel p{margin:0;font-size:12px;line-height:1.7;color:#77718c}.offline-panel .ready{color:#268357}.offline-panel button{min-height:44px;flex-shrink:0}.offline-tools{font-size:13px;line-height:1.8;margin-top:22px;color:#736e88}.offline-tools summary{cursor:pointer;min-height:44px;padding:10px 0}.offline-tools div{display:flex;flex-wrap:wrap}.offline-tools button{color:#6754e8}

.icon-sprite{position:absolute;width:0;height:0;overflow:hidden}.ui-icon{width:24px;height:24px;fill:none;stroke:currentColor;stroke-width:1.9;stroke-linecap:round;stroke-linejoin:round}.icon-button{display:grid;place-items:center;color:var(--primary)}.icon-button .ui-icon{width:25px;height:25px}.achievement-card{width:100%;border:0;text-align:left;font:inherit;color:inherit;cursor:pointer}.achievement-badge{font-size:0;color:#cf922e}.achievement-badge .ui-icon{width:27px;height:27px}
.bottom-nav{padding:7px 10px max(7px,env(safe-area-inset-bottom));border-color:#ebe9f5}.nav-item{min-height:56px;justify-content:center;gap:3px;border-radius:12px;color:#9997aa}.nav-icon{width:27px;height:27px;fill:none;stroke:currentColor;stroke-width:1.9;stroke-linecap:round;stroke-linejoin:round}.nav-item small{font-size:11px;line-height:1.2}.nav-item.active{color:var(--primary);background:#f1efff}.app-shell{padding-bottom:84px}
.page-header{display:flex;align-items:center;justify-content:space-between;margin:5px 0 25px}.page-header h2{font-family:"Arial Rounded MT Bold",system-ui;font-size:28px;margin:0}.header-icon{width:50px;height:50px;border-radius:15px;background:#eee9ff;color:var(--primary);display:grid;place-items:center}.header-icon .ui-icon{width:29px;height:29px}.header-icon.coral-icon{background:#ffe9e5;color:#ea6d59}
.achievement-summary{display:grid;grid-template-columns:repeat(3,1fr);gap:1px;background:#ebe9f5;border:1px solid #ebe9f5;border-radius:18px;overflow:hidden;margin-bottom:28px;box-shadow:0 8px 24px rgba(66,59,133,.07)}.achievement-summary div{background:#fff;padding:17px 5px;text-align:center;display:flex;flex-direction:column}.achievement-summary strong{font-family:"Arial Rounded MT Bold",system-ui;font-size:25px;color:var(--primary)}.achievement-summary span{font-size:10px;color:var(--muted);margin-top:3px}.section-note{font-size:10px;color:var(--muted)}
.badge-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px}.badge-card{min-height:145px;border:1px solid #ebeaf3;border-radius:18px;background:#f2f1f6;padding:15px;display:flex;flex-direction:column;align-items:flex-start;color:#a09eae;opacity:.72}.badge-card.unlocked{background:#fff;border-color:#e2dcff;color:var(--ink);opacity:1;box-shadow:0 8px 24px rgba(66,59,133,.08)}.badge-symbol{width:45px;height:45px;border-radius:14px;background:#e5e3ea;display:grid;place-items:center;margin-bottom:12px}.badge-card.unlocked .badge-symbol{background:#fff1cb;color:#d69726}.badge-symbol .ui-icon{width:25px;height:25px}.badge-card strong{font-size:13px}.badge-card span{font-size:10px;color:var(--muted);margin-top:4px}.topic-heading{margin-top:28px}.topic-progress{background:#fff;border-radius:18px;overflow:hidden;box-shadow:0 8px 24px rgba(66,59,133,.07)}.topic-row{display:grid;grid-template-columns:42px 1fr auto;align-items:center;gap:11px;padding:14px;border-bottom:1px solid #efedf6}.topic-row:last-child{border:0}.topic-symbol{width:40px;height:40px;border-radius:12px;display:grid;place-items:center;font-size:21px;font-weight:800}.topic-symbol.addition{background:#ffe8e4;color:#ed6653}.topic-symbol.pattern{background:#eee8ff;color:#7757d7}.topic-symbol.compare{background:#fff3d7;color:#b97a18}.topic-symbol.shape{background:#e4f1ff;color:#3e82d3}.topic-row div{display:flex;flex-direction:column;gap:2px}.topic-row strong{font-size:13px}.topic-row span:not(.topic-symbol){font-size:10px;color:var(--muted)}.topic-row b{font-size:11px;color:var(--primary);background:#eeebff;border-radius:8px;padding:5px 8px}
.profile-summary{display:flex;align-items:center;gap:14px;padding:18px;background:#fff;border-radius:18px;box-shadow:0 8px 24px rgba(66,59,133,.07);margin-bottom:25px}.profile-avatar{width:52px;height:52px;border-radius:16px;background:linear-gradient(135deg,#6754e8,#8f75ed);color:#fff;display:grid;place-items:center}.profile-avatar .ui-icon{width:28px;height:28px}.profile-summary>div:last-child{display:flex;flex-direction:column;gap:4px}.profile-summary strong{font-size:16px}.profile-summary span{font-size:11px;color:var(--muted)}.settings-section{margin:0 0 26px}.settings-section h3{font-family:"Arial Rounded MT Bold",system-ui;font-size:17px;margin:0 0 11px}.setting-row,.profile-status{display:flex;align-items:center;justify-content:space-between;gap:12px;background:#fff;padding:14px 15px;border-bottom:1px solid #efedf6}.setting-row:first-of-type,.profile-status{border-radius:16px 16px 0 0}.setting-row:last-of-type{border-radius:0 0 16px 16px;border:0}.setting-label{display:flex;align-items:center;gap:12px;min-width:0}.setting-label>.ui-icon{width:25px;height:25px;color:var(--primary);flex:0 0 auto}.setting-label>div{display:flex;flex-direction:column;gap:2px}.setting-label strong{font-size:13px}.setting-label span{font-size:10px;color:var(--muted)}.setting-row select{min-height:40px;max-width:100px;border:1px solid #ded9f2;border-radius:10px;background:#faf9ff;color:var(--primary);font:700 13px inherit;padding:6px}.toggle-control{width:50px;height:30px;border:0;border-radius:18px;background:#d7d5df;padding:3px;cursor:pointer;transition:.2s}.toggle-control span{display:block;width:24px;height:24px;border-radius:50%;background:#fff;box-shadow:0 2px 6px rgba(0,0,0,.15);transition:.2s}.toggle-control[aria-checked="true"]{background:var(--primary)}.toggle-control[aria-checked="true"] span{transform:translateX(20px)}.profile-status{border-radius:16px}.profile-status>.ui-icon{color:#3ba675;flex:0 0 auto}.profile-status p{font-size:12px;color:var(--muted);margin:0;flex:1}.profile-status p.ready{color:#268357}.settings-note{font-size:11px;line-height:1.7;color:var(--muted);margin:11px 3px}.data-actions{display:grid;grid-template-columns:1fr 1fr;gap:10px}.data-button{min-height:54px;border:1px solid #ded9f2;border-radius:14px;background:#fff;color:var(--primary);display:flex;align-items:center;justify-content:center;gap:8px;font:700 12px inherit;cursor:pointer}.data-button .ui-icon{width:21px;height:21px}
@media(max-width:350px){.nav-icon{width:25px;height:25px}.badge-grid{grid-template-columns:1fr}.setting-row{align-items:flex-start;flex-direction:column}.setting-row select{align-self:stretch;max-width:none}}