:root{--o:#f7931a;--bg:#0f1115;--card:#181b22;--tx:#e8e8ea;--mut:#9aa0aa}
*{box-sizing:border-box}body{margin:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;background:var(--bg);color:var(--tx);line-height:1.65}
a{color:var(--o)}header{display:flex;justify-content:space-between;align-items:center;padding:14px 20px;border-bottom:1px solid #222}
.logo{font-weight:800;font-size:1.2rem;text-decoration:none;color:var(--tx)}.logo span{color:var(--o)}
nav a{margin-left:16px;text-decoration:none;color:var(--mut)}nav a:hover{color:var(--o)}
main{max-width:860px;margin:0 auto;padding:24px 18px}h1{line-height:1.2}
.hero{text-align:center}.hero p{color:var(--mut)}
.level{display:flex;flex-wrap:wrap;justify-content:center;gap:10px;margin:10px auto}
.lvl-label{text-align:center;color:var(--mut);font-size:.8rem;text-transform:uppercase;letter-spacing:.1em;margin-top:18px}
.brick{background:var(--card);border:1px solid #2a2e38;border-radius:10px;padding:12px 16px;text-decoration:none;color:var(--tx);min-width:150px;text-align:center;transition:.15s}
.brick:hover{border-color:var(--o);transform:translateY(-2px)}.brick b{display:block}.brick small{color:var(--mut)}
.l0 .brick{background:var(--o);color:#111;border:none}.l0 .brick small{color:#222}

.meta{color:var(--mut);font-size:.9rem}.toggle{display:inline-flex;border:1px solid #333;border-radius:20px;overflow:hidden;margin:10px 0}
.toggle button{background:none;border:0;color:var(--tx);padding:7px 18px;cursor:pointer;font:inherit}.toggle button.on{background:var(--o);color:#111}
.video{aspect-ratio:16/9;background:var(--card);border:2px dashed #333;border-radius:10px;display:flex;align-items:center;justify-content:center;color:var(--mut);text-align:center;padding:20px}
.video iframe{width:100%;height:100%;border:0}
.term{color:var(--o);border-bottom:1px dashed var(--o);cursor:pointer}
#pop{position:absolute;max-width:300px;background:#22262f;border:1px solid var(--o);border-radius:8px;padding:10px 12px;font-size:.9rem;display:none;z-index:9;box-shadow:0 6px 20px #0008}
#pop b{color:var(--o);display:block}
.related{display:flex;flex-wrap:wrap;gap:8px}.crumb{font-size:.85rem;color:var(--mut)}
#map{width:100%;height:75vh;background:var(--card);border-radius:12px}
#map text{fill:var(--tx);font-size:12px;pointer-events:none}#map circle{cursor:pointer;stroke:#111;stroke-width:2}
@media(max-width:600px){.brick{min-width:130px;padding:10px}nav a{margin-left:10px}}
#pop a.more{display:table;margin-top:8px;background:var(--o);color:#111;text-decoration:none;font-weight:600;padding:4px 10px;border-radius:14px;font-size:.85rem}
.tag{display:inline-block;background:var(--card);border:1px solid #2a2e38;border-radius:14px;padding:3px 10px;margin:3px;text-decoration:none;font-size:.85rem}
.sources{margin-top:2em;font-size:.9em;opacity:.9}.sources ol{padding-left:1.4em}.sources a{color:inherit}
details.tier{border:1px solid #23262e;border-radius:12px;margin:12px auto;padding:6px 10px;background:#13151a}
details.tier summary{cursor:pointer;list-style:none;text-align:center;padding:6px;color:var(--tx)}details.tier summary::-webkit-details-marker{display:none}
details.tier summary::before{content:"▸ ";color:var(--o)}details[open].tier summary::before{content:"▾ "}
.lvl{font-weight:700;text-transform:uppercase;letter-spacing:.08em;font-size:.85rem}.cnt{display:block;color:var(--mut);font-size:.8rem}
.badge{display:inline-block;font-size:.72rem;padding:1px 8px;border-radius:10px;font-weight:700;color:#111;vertical-align:middle}
.b0{background:#f7931a}.b1,.b2{background:#7bd88f}.b3{background:#e3c27a}.b4{background:#b48cff}.b5{background:#ff6b8b}
.tier.t0{max-width:300px}.tier.t1{max-width:480px}.tier.t2{max-width:640px}.tier.t3{max-width:760px}.tier.t4,.tier.t5{max-width:860px}
.brick.tm{min-width:120px;padding:8px 12px;border-style:dashed;font-size:.9rem}.brick.soon{opacity:.5;border-style:dotted;cursor:default}.brick.soon:hover{transform:none;border-color:#2a2e38}
.ctl{display:flex;flex-wrap:wrap;gap:6px;justify-content:center;margin:8px 0}.ctl button{background:var(--card);color:var(--tx);border:1px solid #333;border-radius:14px;padding:4px 12px;cursor:pointer;font:inherit;font-size:.85rem}.ctl button.on{border-color:var(--o);color:var(--o)}.ctl label{font-size:.85rem;color:var(--mut)}
.legend{text-align:center}.brick-k{color:var(--o)}.term-k{color:#e3c27a}.soon-k{color:#666}

.brick .trk{display:block;font-style:normal;font-size:.7em;opacity:.75;margin-top:2px}
#trk button{font-size:.85em}

/* layout: header container + desktop */
header{display:block;padding:0}.hin{display:flex;justify-content:space-between;align-items:center;padding:14px 20px;max-width:1200px;margin:0 auto;gap:12px;flex-wrap:wrap}
.side .box{background:var(--card);border:1px solid #23262e;border-radius:12px;padding:14px 16px;margin-top:18px}.side h4{margin:0 0 10px;font-size:.85rem;text-transform:uppercase;letter-spacing:.08em;color:var(--mut)}.side p{margin:.3em 0}
.side .related{flex-direction:column}.side .related .brick{text-align:left;min-width:0}
@media(min-width:1024px){
main{max-width:1200px;padding:32px 28px}
header nav a{margin-left:28px;font-size:1rem;padding:6px 0;border-bottom:2px solid transparent}header nav a:hover{border-bottom-color:var(--o)}
.hin{padding:16px 28px}.logo{font-size:1.35rem}
main.page{display:grid;grid-template-columns:minmax(0,720px) 320px;gap:48px;justify-content:center;align-items:start}
.maincol{min-width:0}.maincol article{font-size:1.08rem;line-height:1.75}
.side{position:sticky;top:20px}.side .box:first-child{margin-top:0}
.hero h1{font-size:2.6rem}.hero p{font-size:1.1rem;max-width:760px;margin-left:auto;margin-right:auto}
details.tier .level{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:12px;padding:6px 8px 12px}
.tier.t0{max-width:420px}.tier.t0 .level{grid-template-columns:1fr}.tier.t1{max-width:680px}.tier.t2{max-width:880px}.tier.t3{max-width:1040px}.tier.t4,.tier.t5{max-width:1200px}
.brick{min-width:0}
main.wide{max-width:1400px}#wrap{max-height:85vh!important}
}
@media(min-width:1400px){main.page{grid-template-columns:minmax(0,760px) 340px;gap:64px}}

@keyframes tierIn{from{opacity:0;transform:translateY(-6px)}to{opacity:1;transform:none}}details.tier[open]>.level{animation:tierIn .25s ease}details.tier summary:focus-visible{outline:2px solid var(--o);outline-offset:2px;border-radius:8px}@media (prefers-reduced-motion:reduce){details.tier[open]>.level{animation:none}}

/* Previous / Next topic navigation */
.pn{display:flex;gap:12px;margin:2em 0 1.25em;flex-wrap:wrap;border-top:1px solid #2a2e38;padding-top:1.25em}
.pn a{flex:1 1 160px;background:var(--card);border:1px solid #2a2e38;border-radius:12px;padding:14px 16px;text-decoration:none;color:var(--tx);transition:.15s;min-width:0}
.pn a:hover{border-color:var(--o);transform:translateY(-1px)}
.pn-label{display:block;font-size:.72rem;text-transform:uppercase;letter-spacing:.08em;color:var(--o);font-weight:700;margin-bottom:4px}
.pn-title{display:block;font-weight:600;line-height:1.35}
.pn-next{text-align:right}
.pn-empty{flex:1 1 160px;visibility:hidden;pointer-events:none;min-width:0}
@media(max-width:600px){.pn{flex-direction:column}.pn-next{text-align:left}.pn-empty{display:none}}