:root{
      --ink:#183028;--muted:#61736c;--paper:#fbfcf8;--card:#fff;
      --line:#dce8df;--mint:#eaf7ef;--green:#2f8f62;--green2:#65b987;
      --red:#ef6f6c;--blue:#5b83d7;--gold:#e8aa3d;--shadow:0 18px 45px rgba(36,73,55,.10);
      --radius:22px;
    }
    *{box-sizing:border-box}
    html{scroll-behavior:smooth}
    body{margin:0;background:linear-gradient(180deg,#f4fbf6 0,#fff 420px);color:var(--ink);
      font-family:Inter,system-ui,-apple-system,"Segoe UI",sans-serif;line-height:1.65}
    button{font:inherit}
    .page{width:min(1120px,calc(100% - 28px));margin:auto;padding:42px 0 80px}
    .hero{padding:52px clamp(22px,5vw,64px);border:1px solid var(--line);border-radius:30px;
      background:radial-gradient(circle at 92% 5%,#dff6e7 0,transparent 34%),var(--card);box-shadow:var(--shadow)}
    .eyebrow{font-size:.78rem;letter-spacing:.12em;text-transform:uppercase;font-weight:800;color:var(--green)}
    h1{font-size:clamp(2.15rem,6vw,4.8rem);line-height:1.04;max-width:900px;margin:.35em 0 .28em;letter-spacing:-.045em}
    .lead{font-size:clamp(1.08rem,2vw,1.35rem);max-width:760px;color:var(--muted)}
    .hero-nav{display:flex;gap:10px;flex-wrap:wrap;margin-top:28px}
    .pill{display:inline-flex;padding:9px 14px;border-radius:999px;background:var(--mint);color:var(--ink);text-decoration:none;font-weight:700}
    section{margin-top:70px}
    h2{font-size:clamp(1.65rem,4vw,2.65rem);line-height:1.15;letter-spacing:-.025em;margin:0 0 20px}
    h3{font-size:1.25rem;margin:0 0 10px}
    p{margin:0 0 1em}
    .prose{max-width:820px}
    .cards{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
    .card,.note,.app-shell{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow)}
    .card{padding:22px}
    .card b{display:block;font-size:2rem;color:var(--green);margin-bottom:8px}
    .note{padding:22px 24px;border-left:5px solid var(--gold);max-width:850px}
    .two-col{display:grid;grid-template-columns:1fr 1fr;gap:20px;align-items:start}
    .algorithm{counter-reset:step;display:grid;gap:14px;max-width:900px}
    .algorithm>div{counter-increment:step;padding:18px 20px 18px 66px;position:relative;background:#f7fbf8;border-radius:18px;border:1px solid var(--line)}
    .algorithm>div::before{content:counter(step);position:absolute;left:18px;top:18px;width:32px;height:32px;border-radius:50%;
      display:grid;place-items:center;background:var(--green);color:white;font-weight:800}
    .mini-grid{--s:34px;display:grid;grid-template-columns:repeat(var(--cols),var(--s));gap:2px;width:max-content;padding:2px;background:#b8c8be;border-radius:8px}
    .mini-grid i{width:var(--s);height:var(--s);display:block;background:white}
    .mini-grid i.on{background:var(--blue)}
    .mini-grid i.a{background:var(--red)}
    .mini-grid i.b{background:var(--green2)}
    .example-row{display:flex;gap:24px;flex-wrap:wrap;align-items:center}
    code{background:#edf4ef;padding:.12em .4em;border-radius:5px}
    .app-shell{padding:clamp(18px,4vw,34px)}
    .app-head{display:flex;justify-content:space-between;gap:20px;align-items:start;margin-bottom:20px}
    .app-head p{color:var(--muted);max-width:700px}
    .toolbar{display:flex;gap:10px;flex-wrap:wrap;margin:18px 0}
    .btn{border:0;border-radius:13px;padding:11px 16px;font-weight:800;cursor:pointer;background:var(--green);color:#fff;box-shadow:0 6px 16px rgba(47,143,98,.20)}
    .btn.secondary{background:#eef4f0;color:var(--ink);box-shadow:none}
    .btn.danger{background:#d95754}
    .btn:disabled{opacity:.45;cursor:not-allowed}
    .workspace{display:grid;grid-template-columns:minmax(310px,1fr) minmax(250px,.75fr);gap:24px}
    .grid-wrap{overflow:auto;padding:10px 2px}
    #grid{--cell:42px;display:grid;grid-template-columns:repeat(10,var(--cell));gap:3px;width:max-content;touch-action:none}
    .cell{width:var(--cell);height:var(--cell);border:1px solid #cfdcd3;border-radius:7px;background:#f7faf8;cursor:pointer;transition:.12s}
    .cell:hover{transform:translateY(-1px);border-color:#83ab92}
    .cell.active{background:var(--blue);border-color:#3f67b7}
    .cell.part-a{background:var(--red);border-color:#cc514f}
    .cell.part-b{background:var(--green2);border-color:#3b9665}
    .panel{background:#f6faf7;border:1px solid var(--line);border-radius:18px;padding:18px}
    .status{min-height:54px;font-weight:750}
    .status.error{color:#b33936}.status.ok{color:#23754e}.status.warn{color:#a36a08}
    .stats{font-size:.9rem;color:var(--muted);display:grid;gap:5px}
    progress.progress{display:block;width:100%;height:12px;margin:14px 0 10px;accent-color:var(--green)}
    progress.progress::-webkit-progress-bar{background:#dfe9e2;border-radius:999px}
    progress.progress::-webkit-progress-value{background:var(--green);border-radius:999px}
    progress.progress::-moz-progress-bar{background:var(--green);border-radius:999px}
    .progress-text{text-align:right;font-size:.82rem;color:var(--muted);margin-top:-8px;margin-bottom:10px;font-variant-numeric:tabular-nums}
    .solution-nav{display:none;gap:8px;align-items:center;flex-wrap:wrap;margin-top:14px}
    .solution-nav.show{display:flex}
    .legend{display:flex;gap:14px;flex-wrap:wrap;font-size:.9rem;margin-top:14px;color:var(--muted)}
    .dot{display:inline-block;width:12px;height:12px;border-radius:3px;margin-right:5px;vertical-align:-1px}
    details{border-top:1px solid var(--line);padding:16px 0}
    summary{font-weight:800;cursor:pointer}
    .footer-note{margin-top:65px;padding:24px;border-radius:20px;background:#17372b;color:#edf8f1}

    .number-grid{display:grid;grid-template-columns:repeat(var(--cols),var(--s));gap:2px;width:max-content;padding:2px;background:#b8c8be;border-radius:8px}
    .number-grid i{width:var(--s);height:var(--s);display:grid;place-items:center;background:var(--blue);color:white;font-style:normal;font-size:.78rem;font-weight:800}
    .number-grid i.empty{background:white;color:transparent}
    .coloring-strip{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin-top:20px}
    .coloring-card{padding:18px;border:1px solid var(--line);border-radius:18px;background:var(--card)}
    .coloring-card strong,.coloring-card span{display:block}.coloring-card strong{margin-bottom:10px}.coloring-card span{margin-top:10px;color:var(--muted)}
    .positions-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:14px}
    .position-card{padding:15px;border:1px solid var(--line);border-radius:18px;background:var(--card);display:grid;gap:10px;justify-items:start}
    .position-card>b{width:28px;height:28px;border-radius:50%;display:grid;place-items:center;background:var(--mint);color:var(--green)}
    .position-card>span{font-weight:800}
    .deep-dive{border:1px solid var(--line);border-radius:22px;background:var(--card);padding:0;box-shadow:var(--shadow)}
    .deep-dive summary{padding:20px 24px;font-size:1.05rem}
    .deep-content{padding:0 24px 24px}
    .coord-demo{display:flex;gap:20px;align-items:center;flex-wrap:wrap;margin:16px 0}
    .normalization{display:flex;gap:12px;align-items:center;flex-wrap:wrap;margin:14px 0}


    .coordinate-table{display:grid;grid-template-columns:110px repeat(4,minmax(82px,1fr));min-width:520px;border:1px solid var(--line);border-radius:14px;overflow:hidden;margin:18px 0}
    .coordinate-table>div{padding:10px 8px;text-align:center;border-right:1px solid var(--line);border-bottom:1px solid var(--line);background:#fff;font-family:ui-monospace,SFMono-Regular,Consolas,monospace;font-size:.88rem}
    .coordinate-table .coord-head{background:#edf4ef;font-family:inherit;font-weight:800}
    .deep-content{overflow-x:auto}


    .formula-card{max-width:850px;padding:24px;border:1px solid var(--line);border-radius:22px;background:var(--card);box-shadow:var(--shadow)}
    .big-formula{text-align:center;font-family:"Times New Roman",serif;font-size:clamp(1.5rem,4vw,2.2rem);padding:12px;margin:12px 0;background:#f1f7f3;border-radius:14px}
    .growth-table-wrap{overflow-x:auto;margin:22px 0}
    .growth-table{width:100%;border-collapse:collapse;min-width:650px;background:var(--card);border:1px solid var(--line)}
    .growth-table th,.growth-table td{padding:12px 14px;text-align:right;border-bottom:1px solid var(--line)}
    .growth-table th:first-child,.growth-table td:first-child{text-align:left}
    .growth-table thead th{background:#edf5ef;color:var(--ink)}
    .growth-table tbody tr:last-child td{border-bottom:0}
    .bad-note{border-left-color:var(--red)}


    .check-control,.select-control{display:inline-flex;align-items:center;gap:8px;padding:9px 12px;border-radius:12px;background:#eef4f0;font-weight:700}
    .select-control select{font:inherit;border:1px solid var(--line);border-radius:8px;padding:5px 8px;background:white}
    .limit-note{padding:12px 15px;background:#fff8e8;border:1px solid #f0d79d;border-radius:14px;margin-bottom:18px;color:#73531d}
    .multi-grid{--cell:38px;display:grid;grid-template-columns:repeat(10,var(--cell));gap:3px;width:max-content;touch-action:none}
    .multi-grid .cell{width:var(--cell);height:var(--cell)}
    .part-0{background:#ef6f6c!important;border-color:#c94d4a!important}
    .part-1{background:#65b987!important;border-color:#3b8e62!important}
    .part-2{background:#e8aa3d!important;border-color:#b87a12!important}
    .part-3{background:#8d79d6!important;border-color:#6854b8!important}
    .part-color-0{background:#ef6f6c}.part-color-1{background:#65b987}.part-color-2{background:#e8aa3d}.part-color-3{background:#8d79d6}
    .multi-legend{display:flex;gap:14px;flex-wrap:wrap;margin-top:12px;color:var(--muted)}
    .growth-steps{display:grid;grid-template-columns:repeat(4,1fr);gap:14px}
    .growth-card{padding:18px;border:1px solid var(--line);border-radius:18px;background:var(--card)}
    .growth-card>strong{display:block;margin-bottom:12px}
    .growth-grid{--s:30px;display:grid;grid-template-columns:repeat(var(--cols),var(--s));gap:2px;width:max-content;background:#c8d4cc;padding:2px;border-radius:8px}
    .growth-grid i{width:var(--s);height:var(--s);background:white}
    .growth-grid i.seed{background:var(--red)}
    .growth-grid i.frontier{background:#ffe2a6;box-shadow:inset 0 0 0 3px var(--gold)}
    .fit-example{display:flex;align-items:center;gap:18px;flex-wrap:wrap;margin-top:20px}
    .fit-panel{padding:18px;border:1px solid var(--line);border-radius:18px;background:var(--card)}
    .fit-panel>strong{display:block;margin-bottom:10px}
    .fit-arrow{font-weight:800;color:var(--green)}
    mjx-container{overflow-x:auto;overflow-y:hidden}


    .part-4{background:#45a9b8!important;border-color:#287f8c!important}
    .part-5{background:#d77bad!important;border-color:#a64f80!important}
    .part-color-4{background:#45a9b8}.part-color-5{background:#d77bad}
    .phase-row{font-weight:800;color:var(--green);margin-top:6px}

    @media(max-width:800px){.cards,.two-col,.workspace,.coloring-strip,.positions-grid,.growth-steps{grid-template-columns:1fr}.page{width:min(100% - 18px,1120px)}.hero{padding:34px 22px}#grid{--cell:34px}.app-head{display:block}}
    @media(max-width:390px){#grid{--cell:30px}}
  
.project-nav{position:sticky;top:10px;z-index:50;display:flex;justify-content:space-between;align-items:center;gap:16px;
  margin:0 0 18px;padding:10px 12px 10px 16px;border:1px solid rgba(220,232,223,.92);border-radius:18px;
  background:rgba(255,255,255,.88);backdrop-filter:blur(16px);box-shadow:0 10px 28px rgba(36,73,55,.08)}
.project-nav a{text-decoration:none;color:var(--ink);font-weight:800}.project-nav .brand{color:var(--green)}
.project-nav-links{display:flex;gap:6px}.project-nav-links a{min-width:34px;height:34px;padding:0 9px;border-radius:10px;background:#eef5f0;display:grid;place-items:center}
.five-cards{display:grid;grid-template-columns:repeat(5,1fr);gap:12px}.five-cards article{padding:18px;border-radius:19px;background:#fff;border:1px solid var(--line);box-shadow:var(--shadow)}
.five-cards b{display:grid;place-items:center;width:34px;height:34px;border-radius:10px;background:var(--mint);color:var(--green);font-size:1.15rem;margin-bottom:12px}
.five-cards h3{font-size:1.05rem}.five-cards p{font-size:.9rem;color:var(--muted);margin:0}
.program-section{scroll-margin-top:80px}.program-purple{--section-accent:#775fd0}.program-orange{--section-accent:#d8852e}.program-violet{--section-accent:#6f5bbd}
.program-section>.eyebrow{color:var(--section-accent)}
.program-frame{display:block;width:100%;height:1050px;border:0;margin-top:24px;background:transparent;border-radius:24px;overflow:hidden}
.program-frame.tall{height:1250px}
.math-details{margin-top:22px;border:1px solid var(--line);border-radius:18px;background:#fff;box-shadow:0 10px 28px rgba(36,73,55,.06)}
.math-details summary{cursor:pointer;padding:17px 20px;font-weight:850}.math-details>div{padding:0 20px 20px}.math-details ol{margin-bottom:0}
.formula{font-family:Georgia,'Times New Roman',serif;font-style:italic;white-space:nowrap}
.filter-flow{display:flex;align-items:center;gap:9px;flex-wrap:wrap;margin:20px 0 24px}.filter-flow span{padding:10px 13px;border-radius:999px;background:#f2effc;border:1px solid #d9cff7;font-weight:800}.filter-flow i{font-style:normal;color:var(--muted)}
.table-wrap{overflow:auto;border:1px solid var(--line);border-radius:20px;background:#fff;box-shadow:var(--shadow)}
.comparison-table{width:100%;border-collapse:collapse;min-width:760px}.comparison-table th,.comparison-table td{padding:15px 17px;text-align:left;border-bottom:1px solid var(--line);vertical-align:top}.comparison-table th{background:#f2f8f4}.comparison-table tbody tr:last-child td{border-bottom:0}.comparison-table td:first-child{font-weight:900;color:var(--green);font-size:1.2rem}
.project-footer{display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap}.project-footer span{color:var(--muted)}
@media(max-width:950px){.five-cards{grid-template-columns:repeat(2,1fr)}.program-frame{height:1180px}.program-frame.tall{height:1420px}}
@media(max-width:650px){.project-nav .brand{display:none}.project-nav{justify-content:center}.project-nav-links{width:100%;justify-content:space-between}.five-cards{grid-template-columns:1fr}.program-frame{height:1400px}.program-frame.tall{height:1650px}}