html,body{margin:0}
[hidden]{display:none!important}
img{max-width:100%}

/* Layout: a workshop bench. Engine on the left stays in view; the right column reads top to bottom as symptom -> cause -> teardown. */
:root{
  --bg:#e9edf1; --panel:#f7f9fb; --ink:#14212e; --muted:#566575; --line:#c6d0da;
  --accent:#b86a00; --accent-fill:#ffb81c; --accent-ink:#221600;
  --easy:#1f7a4d; --mid:#9a6a00; --hard:#b3312b; --stage:#d6dde5;
  --display:"Barlow Condensed","Arial Narrow",Arial,sans-serif;
  --body:"Barlow","Segoe UI",system-ui,sans-serif;
  --mono:"JetBrains Mono",ui-monospace,Menlo,Consolas,monospace;
}
@media (prefers-color-scheme: dark){ :root:not([data-theme="light"]){
  --bg:#111a23; --panel:#18232e; --ink:#e6edf3; --muted:#93a3b3; --line:#2c3a48;
  --accent:#ffb81c; --accent-fill:#ffb81c; --accent-ink:#221600;
  --easy:#55c98d; --mid:#f0c04a; --hard:#ff7b72; --stage:#0c141c; color-scheme:dark } }
:root[data-theme="dark"]{
  --bg:#111a23; --panel:#18232e; --ink:#e6edf3; --muted:#93a3b3; --line:#2c3a48;
  --accent:#ffb81c; --accent-fill:#ffb81c; --accent-ink:#221600;
  --easy:#55c98d; --mid:#f0c04a; --hard:#ff7b72; --stage:#0c141c; color-scheme:dark }

*{box-sizing:border-box}
body{background:var(--bg);color:var(--ink);font-family:var(--body);font-size:16px;line-height:1.5;}
.wrap{max-width:1180px;margin:0 auto;display:flex;flex-direction:column;gap:20px}
header{display:flex;flex-wrap:wrap;align-items:baseline;gap:6px 16px}
h1{font-family:var(--display);font-weight:700;font-size:2.1rem;line-height:1;margin:0;letter-spacing:.01em;text-transform:uppercase}
header p{margin:0;color:var(--muted);max-width:60ch}
.grid{display:grid;grid-template-columns:minmax(0,1.2fr) minmax(0,1fr);gap:20px;align-items:start}
.bench{position:sticky;top:calc(env(safe-area-inset-top, 0px) + 12px);display:flex;flex-direction:column;gap:8px;min-width:0}
.stage{position:relative;background:var(--stage);border:1px solid var(--line);border-radius:4px;aspect-ratio:4/3;max-width:100%;overflow:hidden;touch-action:none}
.stage canvas{display:block;width:100%;height:100%}
.readout{position:absolute;left:10px;bottom:10px;font-family:var(--mono);font-size:.75rem;background:var(--panel);color:var(--ink);border:1px solid var(--line);padding:4px 8px;border-radius:3px;max-width:calc(100% - 20px)}
.tag{position:absolute;left:10px;top:10px;font-family:var(--mono);font-size:.7rem;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.fallback{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;padding:24px;text-align:center;color:var(--muted)}
.hint{font-size:.85rem;color:var(--muted);margin:0}
.switch{display:inline-flex;align-items:center;gap:10px;font-weight:600;cursor:pointer;align-self:flex-start;position:relative}
.switch input{position:absolute;opacity:0;width:44px;height:24px;margin:0;cursor:pointer}
.track{width:44px;height:24px;border-radius:999px;background:var(--line);position:relative;flex:none;transition:background .15s}
.track::after{content:"";position:absolute;top:3px;left:3px;width:18px;height:18px;border-radius:50%;background:var(--panel);transition:transform .15s}
.switch input:checked + .track{background:var(--accent-fill)}
.switch input:checked + .track::after{transform:translateX(20px);background:var(--accent-ink)}
.switch input:focus-visible + .track{outline:2px solid var(--accent);outline-offset:2px}
.fast{display:flex;flex-direction:column;gap:2px;margin-top:6px;font-family:var(--mono);font-size:.78rem}
.fast span{display:flex;align-items:center;gap:8px;font-size:.78rem}
.fast i{width:10px;height:10px;border-radius:50%;border:1px solid var(--ink);flex:none}
.fast i.sq{border-radius:1px}
.toggles{display:flex;flex-wrap:wrap;gap:8px 20px}
@media (prefers-reduced-motion: reduce){ .track,.track::after{transition:none} }
.col{display:flex;flex-direction:column;gap:22px;min-width:0}
section{display:flex;flex-direction:column;gap:10px;min-width:0}
h2{font-family:var(--display);font-weight:600;font-size:1.25rem;letter-spacing:.04em;text-transform:uppercase;margin:0}
.sub{font-size:.75rem;font-family:var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--muted);margin:0}
.chips{display:flex;flex-wrap:wrap;gap:8px}
button{font:inherit;color:inherit;cursor:pointer}
button:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.chip{background:var(--panel);border:1px solid var(--line);border-radius:999px;padding:6px 12px;font-size:.9rem;text-align:left}
.chip.code{font-family:var(--mono);font-size:.8rem;border-radius:3px}
.chip[aria-pressed="true"]{background:var(--accent-fill);border-color:var(--accent-fill);color:var(--accent-ink);font-weight:600}
.link{background:none;border:0;padding:0;color:var(--accent);text-decoration:underline;font-size:.85rem;align-self:flex-start}
.causes{display:flex;flex-direction:column;gap:6px}
.cause{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:2px 12px;align-items:center;background:var(--panel);border:1px solid var(--line);border-radius:4px;padding:10px 12px;text-align:left}
.cause[aria-current="true"]{border-color:var(--accent);box-shadow:inset 0 0 0 1px var(--accent)}
.cause b{font-weight:600}
.cause small{color:var(--muted);grid-column:1}
.pill{font-family:var(--mono);font-size:.7rem;letter-spacing:.05em;text-transform:uppercase;border:1px solid currentColor;border-radius:3px;padding:2px 6px;white-space:nowrap;grid-row:1 / span 2;grid-column:2}
.pill.easy{color:var(--easy)} .pill.mid{color:var(--mid)} .pill.hard{color:var(--hard)}
.job{background:var(--panel);border:1px solid var(--line);border-radius:4px;padding:16px;display:flex;flex-direction:column;gap:12px}
.job h3{font-family:var(--display);font-weight:600;font-size:1.5rem;line-height:1.1;margin:0;text-wrap:balance}
.meta{display:flex;flex-wrap:wrap;gap:8px 14px;align-items:center;font-size:.85rem;color:var(--muted)}
.meta .pill{grid-row:auto}
.job p{margin:0}
.warn{border-left:3px solid var(--hard);padding-left:10px;font-size:.9rem}
.note{border-left:3px solid var(--line);padding-left:10px;font-size:.9rem;color:var(--muted)}
.tba{color:var(--muted);font-style:italic}
table.kit{min-width:0}
.needs{margin:0;padding-left:1.1rem;font-size:.9rem;display:flex;flex-direction:column;gap:4px}
.conf{font-family:var(--mono);font-size:.7rem;letter-spacing:.04em;text-transform:uppercase}
.conf.full{color:var(--easy)} .conf.part{color:var(--mid)}
.srcs{font-size:.8rem;color:var(--muted);overflow-wrap:anywhere}
a{color:var(--accent)}
ol.steps{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:4px;counter-reset:s}
ol.steps li{counter-increment:s}
ol.steps li.phasehead{counter-increment:none;font-family:var(--mono);font-size:.72rem;letter-spacing:.08em;text-transform:uppercase;color:var(--accent);padding:12px 8px 2px;border-top:1px solid var(--line);margin-top:6px}
ol.steps li.phasehead:first-child{border-top:0;margin-top:0;padding-top:2px}
.step{width:100%;display:grid;grid-template-columns:2rem minmax(0,1fr);gap:8px;background:none;border:1px solid transparent;border-radius:4px;padding:8px;text-align:left}
.step::before{content:counter(s);font-family:var(--mono);font-size:.8rem;width:1.75rem;height:1.75rem;border:1px solid var(--line);border-radius:50%;display:flex;align-items:center;justify-content:center;color:var(--muted)}
.step.done{color:var(--muted)}
.step.done::before{content:"\2713";border-color:var(--easy);color:var(--easy)}
.step.now{border-color:var(--line);background:var(--bg)}
.step.now::before{background:var(--accent-fill);border-color:var(--accent-fill);color:var(--accent-ink);font-weight:600}
.step b{display:block;font-weight:600}
.step span{font-size:.9rem}
.nav{display:flex;gap:8px;flex-wrap:wrap}
.btn{background:var(--panel);border:1px solid var(--line);border-radius:4px;padding:8px 16px;font-weight:600}
.btn.primary{background:var(--accent-fill);border-color:var(--accent-fill);color:var(--accent-ink)}
.btn:disabled{opacity:.45;cursor:default}
footer{font-size:.85rem;color:var(--muted);max-width:75ch}
@media (max-width:820px){ .grid{grid-template-columns:minmax(0,1fr)} .bench{position:static} h1{font-size:1.7rem} }

/* ---------- Site chrome ---------- */
html{scroll-behavior:smooth}
@media (prefers-reduced-motion: reduce){ html{scroll-behavior:auto} }
.skip{position:absolute;left:-999px;top:0;background:var(--accent-fill);color:var(--accent-ink);padding:8px 12px;z-index:30}
.skip:focus{left:8px;top:8px}
.top{position:sticky;top:env(safe-area-inset-top, 0px);z-index:20;background:#14212e;color:#e9edf1;border-bottom:3px solid var(--accent-fill)}
.top-in{max-width:1180px;margin:0 auto;padding-inline:16px;display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:4px 24px;min-height:56px}
.brand{display:inline-flex;align-items:center;gap:10px;color:inherit;text-decoration:none;font-family:var(--display);font-weight:700;font-size:1.35rem;letter-spacing:.06em;text-transform:uppercase}
.brand svg{width:26px;height:26px;fill:var(--accent-fill);flex:none}
.top nav{display:flex;flex-wrap:wrap;gap:2px 18px;padding-block:6px}
.top nav a{color:inherit;text-decoration:none;font-size:.9rem;font-weight:500;opacity:.85;padding-block:4px;border-bottom:2px solid transparent}
.top nav a:hover,.top nav a:focus-visible{opacity:1;border-bottom-color:var(--accent-fill);outline:none}
.wrap{padding-inline:16px;padding-block:28px 48px;gap:36px}
.intro{display:flex;flex-direction:column;gap:10px;max-width:70ch}
.kicker{margin:0;font-family:var(--mono);font-size:.78rem;letter-spacing:.08em;text-transform:uppercase;color:var(--accent)}
.intro h1{font-size:clamp(2rem,5vw,3.1rem);line-height:1;text-wrap:balance}
.lede{margin:0;font-size:1.1rem;color:var(--muted)}
.facts{display:flex;flex-wrap:wrap;gap:8px 28px;margin:6px 0 0}
.facts div{display:flex;align-items:baseline;gap:8px}
.facts dt{font-family:var(--display);font-weight:700;font-size:1.7rem;line-height:1}
.facts dd{margin:0;color:var(--muted);font-size:.9rem}
#guide,#how,#jobs,#sources,#safety{scroll-margin-top:calc(env(safe-area-inset-top, 0px) + 76px)}
.bench{top:calc(env(safe-area-inset-top, 0px) + 72px)}
.panelbox{background:var(--panel);border:1px solid var(--line);border-radius:4px;padding:12px 14px;display:flex;flex-direction:column;gap:8px}
.band{border-top:1px solid var(--line);padding-top:28px;gap:16px}
.band > h2{font-size:1.7rem;letter-spacing:.03em}
.band > p{margin:0;max-width:70ch;color:var(--muted)}
.how{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:16px;counter-reset:h}
.how li{counter-increment:h;display:flex;flex-direction:column;gap:6px;min-width:0}
.how li::before{content:counter(h);font-family:var(--display);font-weight:700;font-size:2.2rem;line-height:1;color:var(--accent)}
.how b{font-family:var(--display);font-weight:600;font-size:1.2rem;letter-spacing:.03em;text-transform:uppercase}
.how span{color:var(--muted)}
.tablewrap{overflow-x:auto;border:1px solid var(--line);border-radius:4px;background:var(--panel)}
table{border-collapse:collapse;width:100%;min-width:620px;font-size:.92rem}
th,td{text-align:left;padding:10px 14px;border-bottom:1px solid var(--line);vertical-align:top}
tr:last-child td{border-bottom:0}
th{font-family:var(--mono);font-size:.7rem;letter-spacing:.08em;text-transform:uppercase;color:var(--muted);font-weight:600}
td .pill{grid-row:auto}
td .link{font-size:.95rem;font-weight:600;text-align:left}
td.num{font-variant-numeric:tabular-nums}
.srclist{margin:0;padding:0;list-style:none;display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:8px 24px;font-size:.92rem}
.srclist li{overflow-wrap:anywhere}
.safety{margin:0;padding-left:1.1rem;display:flex;flex-direction:column;gap:8px;max-width:75ch}
.foot{max-width:none;background:#0c141c;color:#e9edf1;border-top:1px solid #2c3a48;font-size:.85rem}
.foot-in{max-width:1180px;margin:0 auto;padding-inline:16px;padding-block:20px;display:flex;flex-wrap:wrap;gap:6px 24px;justify-content:space-between}
.foot p{margin:0;opacity:.85;max-width:80ch}
@media (max-width:820px){ .top nav{gap:2px 14px} .top nav a{font-size:.85rem} }

/* ---------- Home ---------- */
a.btn{display:inline-block;text-decoration:none;color:var(--ink)}
a.btn.primary{color:var(--accent-ink)}
.kicker a{color:inherit}
.picker{background:var(--panel);border:1px solid var(--line);border-radius:4px;padding:20px;display:flex;flex-direction:column;gap:14px;max-width:760px}
.picker h2{font-size:1.4rem}
.fields{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:12px}
.field{display:flex;flex-direction:column;gap:4px;min-width:0}
.field label{font-family:var(--mono);font-size:.7rem;letter-spacing:.08em;text-transform:uppercase;color:var(--muted)}
.field select{font:inherit;color:var(--ink);background:var(--bg);border:1px solid var(--line);border-radius:4px;padding:10px 12px;width:100%}
.field select:disabled{opacity:.45;cursor:not-allowed}
.field select:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.picker .btn{align-self:flex-start;font-size:1.05rem;padding:10px 22px}
.picker .btn[aria-disabled="true"]{opacity:.45;pointer-events:none}
.pickmsg{margin:0;font-size:.9rem;color:var(--muted)}
.vehgrid{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:12px}
button.veh{font:inherit;text-align:left;cursor:pointer;width:100%}
.yearbox{max-width:900px}
.yearbox .safety{max-width:none}
.buildlist{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:12px}
.build{background:var(--panel);border:1px solid var(--line);border-radius:4px;padding:20px;display:grid;grid-template-columns:minmax(0,1.4fr) minmax(0,1fr);gap:20px;align-items:end}
.build h3{font-family:var(--display);font-weight:600;font-size:1.6rem;line-height:1.1;margin:0 0 6px}
.build p{margin:0 0 6px}
.buildpick{display:flex;flex-direction:column;gap:10px;min-width:0}
.buildpick .btn{align-self:flex-start}
.buildpick .btn[aria-disabled="true"]{opacity:.45;pointer-events:none}
@media (max-width:820px){ .build{grid-template-columns:minmax(0,1fr)} }
.veh{display:flex;flex-direction:column;gap:4px;background:var(--panel);border:1px solid var(--line);border-radius:4px;padding:16px;text-decoration:none;color:var(--ink);height:100%}
.veh:hover,.veh:focus-visible{border-color:var(--accent);outline:none}
.veh b{font-family:var(--display);font-weight:600;font-size:1.4rem;line-height:1.1}
.veh span{color:var(--muted);font-size:.9rem}
.veh em{font-style:normal;font-family:var(--mono);font-size:.72rem;letter-spacing:.06em;text-transform:uppercase;color:var(--accent);margin-top:6px}