:root{--font-ui: "SF Pro Display", "SF Pro Text", "PingFang SC", "Hiragino Sans GB", "Helvetica Neue", sans-serif;--color-bg: #f5f5f7;--color-bg-soft: #fafafc;--color-card: #ffffff;--color-card-soft: #f8f8fb;--color-border: rgba(15, 23, 42, .08);--color-text: #1d1d1f;--color-text-muted: #6e6e73;--color-accent: #0071e3;--color-accent-strong: #0062c3;--shadow-card: 0 20px 45px rgba(15, 23, 42, .08);--shadow-soft: 0 8px 20px rgba(15, 23, 42, .06);--radius-xl: 32px;--radius-lg: 24px;--radius-md: 16px;--radius-sm: 12px;--page-width: 1200px}*{box-sizing:border-box}html,body,#root{min-height:100%}body{margin:0;min-height:100vh;color:var(--color-text);font-family:var(--font-ui);line-height:1.5;background:radial-gradient(1400px 500px at 50% -10%,#0071e31a,#0071e300),linear-gradient(180deg,#fcfcfe 0%,var(--color-bg) 58%,#f0f1f4 100%)}a{color:inherit;text-decoration:none}h1,h2,h3,h4{margin:0;line-height:1.15;letter-spacing:0}p{margin:0;color:var(--color-text-muted)}button,input{font-family:inherit}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.math-page{width:min(1120px,100%);margin:0 auto}.math-hero{min-height:286px;display:grid;grid-template-columns:minmax(0,1.2fr) minmax(300px,.8fr);align-items:center;gap:56px;padding:44px 52px;border:1px solid rgba(0,113,227,.08);border-radius:var(--radius-xl);background:radial-gradient(circle at 84% 18%,rgba(76,175,255,.2),transparent 32%),linear-gradient(135deg,#fffffffa,#f3f8fff5);box-shadow:var(--shadow-card)}.math-hero__eyebrow{display:block;margin-bottom:14px;color:var(--color-accent);font-size:.72rem;font-weight:800;letter-spacing:.14em}.math-hero h1{max-width:640px;font-size:clamp(2.15rem,4.3vw,4rem);letter-spacing:-.055em}.math-hero__copy p{margin-top:18px;font-size:1.08rem}.math-search{min-height:58px;display:flex;align-items:center;gap:12px;padding:0 18px;border:1px solid rgba(0,113,227,.13);border-radius:18px;background:#fffffff0;box-shadow:var(--shadow-soft);color:var(--color-accent);font-size:1.55rem}.math-search:focus-within{box-shadow:0 0 0 4px #0071e31f,var(--shadow-soft)}.math-search input{width:100%;border:0;outline:0;background:transparent;color:var(--color-text);font-size:.95rem}.math-view-switcher,.math-sub-switcher,.math-grade-switcher{display:flex;width:max-content;max-width:100%;overflow-x:auto;gap:5px;padding:5px;margin:30px auto 0;border-radius:999px;background:#e2e4e9b8;scrollbar-width:none}.math-view-switcher button,.math-sub-switcher button,.math-grade-switcher button{min-height:44px;padding:0 22px;border:0;border-radius:999px;background:transparent;color:var(--color-text-muted);font-weight:720;white-space:nowrap;cursor:pointer}.math-view-switcher button.is-active,.math-sub-switcher button.is-active,.math-grade-switcher button.is-active{background:#fff;color:var(--color-text);box-shadow:0 3px 12px #0f172a17}.math-sub-switcher{margin-top:18px}.math-grade-area{margin-top:18px;text-align:center}.math-grade-switcher{margin-top:0}.math-grade-area>p{margin-top:10px;font-size:.82rem}.math-view-heading{margin:46px 2px 22px}.math-view-heading h2{font-size:clamp(1.6rem,3vw,2.25rem)}.math-view-heading p{margin-top:8px}.math-domain-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px;align-items:start}.math-domain-card,.math-section{--domain-accent: #1677d2;padding:26px;overflow:hidden;border:1px solid var(--color-border);border-radius:var(--radius-lg);background:#ffffffe6;box-shadow:var(--shadow-soft)}.math-domain-card--operation{--domain-accent: #df704b}.math-domain-card--algebra{--domain-accent: #7056b8}.math-domain-card--geometry{--domain-accent: #17856d}.math-domain-card--data{--domain-accent: #bd7c19}.math-domain-card:last-child{grid-column:1 / -1}.math-domain-card__toggle,.math-section__head{width:100%;min-height:52px;display:flex;align-items:center;gap:15px;padding:0;border:0;background:transparent;color:var(--color-text);text-align:left;cursor:pointer}.math-domain-card__name{min-width:0;flex:1;display:flex;flex-direction:column}.math-domain-card__name strong{font-size:1.45rem;line-height:1.2}.math-domain-card__name small{margin-top:2px;color:var(--color-text-muted);font-size:.8rem}.math-domain-card__chevron{margin-left:auto;color:var(--color-text-muted);font-size:1.7rem;transform:rotate(0);transition:transform .15s ease}[aria-expanded=true]>.math-domain-card__chevron{transform:rotate(90deg)}.math-domain-card__icon,.math-section__head>span:first-child{min-width:50px;min-height:50px;display:inline-flex;align-items:center;justify-content:center;padding:0 7px;border-radius:15px;background:color-mix(in srgb,var(--domain-accent) 11%,white);color:var(--domain-accent);font-size:1rem;font-weight:820}.math-domain-card__description{margin:16px 0 12px;font-size:.9rem}.math-tree{list-style:none;margin:0;padding:0}.math-tree-node{padding-left:min(calc(var(--tree-depth) * 16px),48px)}.math-tree-node__row{min-height:48px;display:flex;align-items:center;gap:7px;border-top:1px solid rgba(15,23,42,.055)}.math-tree--root>.math-tree-node:first-child>.math-tree-node__row{border-top:0}.math-tree-node__toggle{width:34px;min-width:34px;height:44px;padding:0;border:0;background:transparent;color:var(--color-text-muted);cursor:pointer}.math-tree-node__toggle span{display:block;font-size:1.35rem;transform:rotate(0);transition:transform .15s ease}.math-tree-node__toggle[aria-expanded=true] span{transform:rotate(90deg)}.math-tree-node__leaf{width:34px;min-width:34px;text-align:center;color:#b3b3b8}.math-tree-node__main{min-width:0;flex:1;padding:8px 0}.math-tree-node__title{color:#a1a1a6;font-size:.94rem;font-weight:700}.math-tree-node__title>a,.math-tree-node__title>span{display:inline-flex;flex-direction:column;align-items:flex-start}.math-tree-node__title small{margin-top:2px;color:var(--color-text-muted);font-size:.72rem;font-weight:500;line-height:1.25}.math-tree-node__title .is-branch{color:var(--color-text)}.math-tree-node__title .is-unavailable{color:#a1a1a6}.math-tree-node__title .is-unavailable small{color:#b3b3b8}.math-tree-node__title a{color:var(--color-accent)}.math-tree-node__title a:hover{text-decoration:underline;text-underline-offset:3px}.math-tree-node__main p{margin-top:3px;font-size:.78rem}.math-section-list{display:grid;gap:18px}.math-section{--domain-accent: var(--color-accent)}.math-section__head strong{flex:1;font-size:1.18rem}.math-section__head>span:first-child{min-width:42px;min-height:42px}.math-section>.math-tree{margin-top:12px}.math-search-results{margin-top:30px;padding:30px;border-radius:var(--radius-lg);background:#ffffffeb;box-shadow:var(--shadow-soft)}.math-search-results__head{display:flex;justify-content:space-between;align-items:center;gap:16px}.math-search-results__head h2{font-size:1.35rem}.math-search-results__head button{min-height:44px;padding:0 16px;border:0;border-radius:999px;background:var(--color-card-soft);color:var(--color-accent);cursor:pointer}.math-search-results ul{list-style:none;margin:22px 0 0;padding:0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.math-search-results li>a,.math-search-results li>div{min-height:72px;display:flex;flex-direction:column;justify-content:center;position:relative;padding:13px 16px;border:1px solid var(--color-border);border-radius:14px;background:var(--color-card-soft)}