@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;500;600;700;800&display=swap');
:root{--paper:#f7f9fa;--white:#fff;--ink:#18222c;--muted:#53616b;--line:#d9e2e7;--blue:#075b99;--sky:#e8f4fc;--violet:#6d5ce8;--gold:#f2c566;--coral:#f27679}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body.learning-page{margin:0;background:var(--paper);color:var(--ink);font:400 16px/1.65 Roboto,'Segoe UI',Arial,sans-serif}
button,input,textarea,select{font:inherit}
code,pre{font-family:Consolas,'Courier New',monospace}
a{color:var(--blue)}
a:hover{color:#043e69}
:focus-visible{outline:3px solid var(--violet);outline-offset:3px}
.skip-link{position:absolute;left:1rem;top:-5rem;z-index:2000;padding:.65rem 1rem;background:#fff;color:#123}
.skip-link:focus{top:1rem}
.page-shell{max-width:1180px;margin:0 auto;padding:0 clamp(1.25rem,5vw,4rem)}
.page-header{border-bottom:1px solid var(--line);background:#fff}
.page-header-inner{min-height:76px;display:flex;align-items:center;justify-content:space-between;gap:1rem}
.wordmark{display:flex;align-items:center;gap:.7rem;text-decoration:none;color:var(--ink)}
.wordmark img{width:37px;height:37px}
.wordmark strong,.wordmark small{display:block;line-height:1.15}
.wordmark strong{font-size:.93rem}.wordmark small{color:var(--muted);font-size:.63rem;letter-spacing:.08em}
.header-utility{display:flex;gap:1rem;align-items:center;font-size:.83rem;font-weight:700}
.header-utility a{text-decoration:none}
.header-utility .utility-cta{padding:.48rem .8rem;border:1px solid var(--blue);border-radius:7px;background:var(--blue);color:#fff}
.page-main{padding-bottom:5rem}
.page-hero{padding:clamp(3.2rem,7vw,6rem) 0 clamp(2.7rem,5vw,4rem);background:linear-gradient(125deg,#fff9e8 0%,#f8faf9 54%,#edf5fa 100%);border-bottom:1px solid var(--line)}
.page-hero .page-shell{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(250px,.65fr);gap:3rem;align-items:end}
.eyebrow{margin:0 0 1.05rem;color:var(--blue);font-size:.76rem;font-weight:800;letter-spacing:.12em;text-transform:uppercase}
.page-hero h1{max-width:18ch;margin:0;color:var(--ink);font-size:clamp(2.45rem,5vw,5rem);line-height:1.08;letter-spacing:-.035em}
.page-hero p.lead{max-width:62ch;margin:1.3rem 0 0;color:var(--muted);font-size:clamp(1rem,1.3vw,1.2rem)}
.hero-note{padding:1.35rem;border-left:4px solid var(--gold);background:#fff;box-shadow:0 16px 38px rgb(13 53 81 / 7%)}
.hero-note strong{display:block;margin-bottom:.35rem}.hero-note p{margin:0;color:var(--muted);font-size:.9rem}
.section{padding:clamp(3rem,6vw,5rem) 0}
.section+.section{border-top:1px solid var(--line)}
.section-head{display:flex;justify-content:space-between;align-items:end;gap:1.5rem;margin-bottom:1.5rem}
.section-head h2,.section h2{margin:0;font-size:clamp(1.7rem,2.8vw,2.55rem);line-height:1.2;letter-spacing:-.025em}
.section-intro{max-width:65ch;margin:.65rem 0 0;color:var(--muted)}
.grid-3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:1.1rem}
.grid-2{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:1.1rem}
.paper-card{padding:1.5rem;border:1px solid var(--line);border-radius:11px;background:#fff}
.paper-card h3{margin:.35rem 0 .55rem;font-size:1.26rem;line-height:1.25}
.paper-card p{margin:.55rem 0;color:var(--muted)}
.card-number{display:inline-block;color:var(--violet);font:700 .82rem Consolas,monospace}
.status{display:inline-flex;align-items:center;padding:.25rem .55rem;border-radius:4px;font-size:.7rem;font-weight:800;letter-spacing:.025em}
.status.live{background:#e3f3e9;color:#195d38}.status.building{background:#fff0ce;color:#704914}.status.planned{background:#e9e9fd;color:#4237a1}
.action-link{display:inline-flex;align-items:center;gap:.35rem;margin-top:1rem;font-size:.9rem;font-weight:800;text-decoration:none}
.button-row{display:flex;flex-wrap:wrap;gap:.65rem;margin-top:1.4rem}
.button{display:inline-flex;align-items:center;justify-content:center;min-height:44px;padding:.65rem 1rem;border:1px solid var(--blue);border-radius:7px;background:var(--blue);color:#fff;text-decoration:none;font-size:.89rem;font-weight:750}
.button:hover{background:#043e69;color:#fff}.button.secondary{background:#fff;color:var(--blue)}.button.secondary:hover{background:var(--sky)}
.plain-list{padding-left:1.2rem;margin:.8rem 0;color:var(--muted)}.plain-list li+li{margin-top:.4rem}
.label{color:var(--ink);font-size:.76rem;font-weight:800;letter-spacing:.04em;text-transform:uppercase}
.sequence{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:0;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.sequence div{padding:1.3rem 1rem 1.3rem 0}.sequence div+div{padding-left:1rem;border-left:1px solid var(--line)}.sequence span{display:block;color:var(--violet);font:700 .78rem Consolas,monospace}.sequence strong{display:block;margin-top:.4rem}
.detail-layout{display:grid;grid-template-columns:minmax(0,1fr) 250px;gap:2.5rem;align-items:start}
.lesson-index{position:sticky;top:1.5rem;padding:1.2rem;border:1px solid var(--line);border-radius:11px;background:#fff}.lesson-index strong{display:block;margin-bottom:.7rem}.lesson-index a{display:block;padding:.4rem 0;text-decoration:none;font-size:.85rem}
.lesson-entry{padding:2rem 0;border-top:1px solid var(--line);scroll-margin-top:1.5rem}.lesson-entry:first-child{padding-top:0;border:0}.lesson-entry h2{margin:.45rem 0 1rem}.lesson-entry h3{margin:1.4rem 0 .4rem;font-size:1.08rem}.lesson-entry p{max-width:75ch;color:#3d4a53}.lesson-entry .label{color:var(--blue)}
.exercise{margin-top:1.4rem;padding:1.2rem 1.3rem;border-left:4px solid var(--gold);background:#fff9e8}.exercise h3{margin:0 0 .45rem}.exercise p{margin:.4rem 0}.exercise details{margin-top:.8rem}.exercise summary{cursor:pointer;color:var(--blue);font-weight:700}
.code-sample{overflow:auto;padding:1.2rem;border-radius:8px;background:#20272c;color:#f4f6f6;font-size:.84rem;line-height:1.65}
.filter-bar{display:flex;flex-wrap:wrap;gap:.45rem;margin-bottom:1.4rem}.filter-button{padding:.5rem .8rem;border:1px solid #cad6dc;border-radius:6px;background:#fff;color:var(--ink);cursor:pointer;font-size:.85rem}.filter-button[aria-pressed=true]{border-color:var(--blue);background:var(--blue);color:#fff}
[hidden]{display:none!important}
.timeline{border-left:2px solid #c5d9e6;margin-left:.5rem;padding-left:1.5rem}.timeline article{position:relative;padding:0 0 2rem}.timeline article::before{content:'';position:absolute;left:-1.94rem;top:.28rem;width:.75rem;height:.75rem;border-radius:50%;background:var(--blue)}.timeline h3{margin:.4rem 0}.timeline p{margin:.5rem 0;color:var(--muted)}
.legal-copy{max-width:76ch}.legal-copy h2{margin:2.5rem 0 .5rem;font-size:1.4rem}.legal-copy p,.legal-copy li{color:#3d4a53}
.page-footer{padding:2rem 0;border-top:1px solid var(--line);background:#fff;color:var(--muted);font-size:.82rem}.page-footer .page-shell{display:flex;justify-content:space-between;flex-wrap:wrap;gap:1rem}.page-footer nav{display:flex;flex-wrap:wrap;gap:1rem}.page-footer a{text-decoration:none}
@media(max-width:900px){.page-hero .page-shell{grid-template-columns:1fr}.grid-3{grid-template-columns:1fr 1fr}.detail-layout{grid-template-columns:1fr}.lesson-index{position:static;order:-1}.sequence{grid-template-columns:repeat(2,1fr)}.sequence div:nth-child(3){border-left:0}}
@media(max-width:620px){.page-header-inner{min-height:66px}.header-utility a:first-child{display:none}.page-hero{padding-top:3.5rem}.grid-3,.grid-2{grid-template-columns:1fr}.sequence{grid-template-columns:1fr}.sequence div{padding-left:0!important;border-left:0!important}.sequence div+div{border-top:1px solid var(--line)}.section-head{display:block}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}