:root{--paper:#f6f4ef;--paper-2:#efece5;--ink:#1c1b19;--ink-2:#6b6a66;--ink-3:#9a988f;--line:#d9d6cf;--accent:#f04e23;--accent-ink:#b8360f;--accent-soft:#fde6dd;--warn-bg:#fff4d6;--warn-ink:#7a5200;--g-frame:#1c1b19;--g-cockpit:#2f6f9f;--g-drivetrain:#b86b00;--g-wheels:#3a7d5c;--g-brakes:#c0392b;--g-contact:#7a4ea3;--font-sans:"Inter", "Noto Sans TC", -apple-system, "PingFang TC", "Microsoft JhengHei", sans-serif;--font-mono:"JetBrains Mono", ui-monospace, Menlo, monospace;--topbar-h:56px;--radius:10px;--shadow:0 1px 2px #1c1b190f, 0 8px 24px #1c1b1914}*{box-sizing:border-box}html,body{height:100%;margin:0}body{background:var(--paper);color:var(--ink);font-family:var(--font-sans);-webkit-font-smoothing:antialiased;text-rendering:optimizelegibility;font-size:17px;line-height:1.7}button{font:inherit;color:inherit}a{color:var(--accent-ink)}kbd{font-family:var(--font-mono);border:1px solid var(--line);background:#fff;border-bottom-width:2px;border-radius:4px;padding:0 5px;font-size:.85em}.app{height:100vh;flex-direction:column;height:100dvh;display:flex}.topbar{height:var(--topbar-h);border-bottom:1px solid var(--line);background:var(--paper);flex:none;align-items:center;gap:16px;padding:0 20px;display:flex}.brand{color:var(--ink);align-items:baseline;gap:10px;text-decoration:none;display:flex}.brand__name{letter-spacing:-.01em;white-space:nowrap;font-size:18px;font-weight:700}.brand__sub{color:var(--ink-2);font-size:14px}.topbar__spacer{flex:1}.toggle{border:1px solid var(--line);cursor:pointer;white-space:nowrap;background:#fff;border-radius:999px;align-items:center;gap:10px;padding:6px 12px 6px 8px;font-size:14px;font-weight:600;transition:border-color .15s,background .15s;display:inline-flex}.toggle__knob{background:var(--line);border-radius:999px;width:30px;height:18px;transition:background .2s;position:relative}.toggle__knob:after{content:"";background:#fff;border-radius:50%;width:14px;height:14px;transition:transform .2s;position:absolute;top:2px;left:2px}.toggle[aria-pressed=true]{border-color:var(--accent);background:var(--accent-soft)}.toggle[aria-pressed=true] .toggle__knob{background:var(--accent)}.toggle[aria-pressed=true] .toggle__knob:after{transform:translate(12px)}.textbtn{color:var(--ink-2);cursor:pointer;background:0 0;border:0;border-radius:6px;padding:6px 8px;font-size:14px}.textbtn:hover{color:var(--ink);background:var(--paper-2)}.layout{flex:auto;grid-template-columns:minmax(0,58fr) minmax(380px,42fr);min-height:0;display:grid}.stage{border-right:1px solid var(--line);background:radial-gradient(120% 90% at 50% 35%,#fff 0%,#ebe8e1 70%,#e2dfd7 100%);min-height:0;position:relative;overflow:hidden}.stage__canvas{cursor:grab;touch-action:none;outline:none;width:100%;height:100%;display:block;position:absolute;inset:0}.stage__canvas:active{cursor:grabbing}.stage__tooltip{pointer-events:none;background:var(--ink);color:#fff;white-space:nowrap;opacity:0;border-radius:6px;padding:4px 9px;font-size:13px;font-weight:600;transition:opacity .12s;position:absolute;transform:translate(14px,14px)}.stage__tooltip.is-visible{opacity:1}.stage__hint{color:var(--ink-2);-webkit-backdrop-filter:blur(6px);backdrop-filter:blur(6px);background:#f6f4efd9;border-radius:6px;padding:4px 10px;font-size:13px;position:absolute;top:14px;left:16px}.stage__status{background:var(--paper);z-index:2;color:var(--ink-2);place-items:center;gap:10px;font-size:15px;transition:opacity .3s;display:grid;position:absolute;inset:0}.stage__status.is-hidden{opacity:0;pointer-events:none}.progress{background:var(--line);border-radius:99px;width:220px;height:4px;overflow:hidden}.progress__bar{background:var(--accent);width:0;height:100%;transition:width .2s}.anchor{border:2px solid var(--accent);width:26px;height:26px;color:var(--accent-ink);font:700 12px var(--font-mono);cursor:pointer;box-shadow:var(--shadow);background:#fff;border-radius:50%;place-items:center;padding:0;transition:opacity .15s;display:grid;position:absolute;transform:translate(-50%,-50%)}.anchor:after{content:"";border:1px solid var(--accent);opacity:.35;border-radius:50%;position:absolute;inset:-6px}.anchor.is-hidden{opacity:0;pointer-events:none}.anchor.is-active{background:var(--accent);color:#fff}.anchor.is-dim{opacity:.35}.index{scrollbar-width:thin;background:linear-gradient(#f6f4ef00,#f6f4eff5 30%);gap:14px;padding:12px 16px 14px;display:flex;position:absolute;bottom:0;left:0;right:0;overflow-x:auto}.index__group{flex:none;align-items:center;gap:6px;display:flex}.index__label{letter-spacing:.08em;text-transform:uppercase;color:var(--ink-3);margin-right:2px;font-size:11px;font-weight:700}.chipbtn{border:1px solid var(--line);cursor:pointer;white-space:nowrap;background:#fff;border-radius:999px;align-items:center;gap:6px;padding:4px 10px 4px 6px;font-size:13px;font-weight:600;transition:border-color .12s,background .12s,color .12s;display:inline-flex}.chipbtn__num{font:700 11px var(--font-mono);background:var(--paper-2);width:22px;height:22px;color:var(--ink-2);border-radius:50%;place-items:center;display:grid}.chipbtn:hover,.chipbtn.is-hover{border-color:var(--ink)}.chipbtn.is-active{background:var(--ink);color:#fff;border-color:var(--ink)}.chipbtn.is-active .chipbtn__num{background:var(--accent);color:#fff}.chipbtn--frame .chipbtn__num{box-shadow:inset 0 0 0 2px var(--g-frame)}.chipbtn--cockpit .chipbtn__num{box-shadow:inset 0 0 0 2px var(--g-cockpit)}.chipbtn--drivetrain .chipbtn__num{box-shadow:inset 0 0 0 2px var(--g-drivetrain)}.chipbtn--wheels .chipbtn__num{box-shadow:inset 0 0 0 2px var(--g-wheels)}.chipbtn--brakes .chipbtn__num{box-shadow:inset 0 0 0 2px var(--g-brakes)}.chipbtn--contact .chipbtn__num{box-shadow:inset 0 0 0 2px var(--g-contact)}.panel{background:var(--paper);min-height:0;padding:28px 32px 48px;overflow-y:auto}.eyebrow{font:700 12px var(--font-mono);letter-spacing:.12em;text-transform:uppercase;color:var(--accent-ink);margin:0 0 8px}.panel__title{letter-spacing:-.02em;margin:0 0 12px;font-size:30px;line-height:1.2}.panel__h3{letter-spacing:.08em;text-transform:uppercase;color:var(--ink-2);margin:28px 0 10px;font-size:13px;font-weight:700}.lead{color:var(--ink);margin:0 0 8px;font-size:18px;line-height:1.65}.panel__note{color:var(--ink-2);border-top:1px solid var(--line);margin-top:24px;padding-top:14px;font-size:14px}.howto{margin:0;padding-left:20px}.howto li{margin-bottom:4px}.legend{grid-template-columns:1fr 1fr;gap:6px 16px;margin:0;padding:0;list-style:none;display:grid}.legend li{align-items:center;gap:8px;font-size:15px;display:flex}.legend__swatch{border-radius:3px;width:12px;height:12px;display:inline-block}.legend__swatch--frame{background:var(--g-frame)}.legend__swatch--cockpit{background:var(--g-cockpit)}.legend__swatch--drivetrain{background:var(--g-drivetrain)}.legend__swatch--wheels{background:var(--g-wheels)}.legend__swatch--brakes{background:var(--g-brakes)}.legend__swatch--contact{background:var(--g-contact)}.legend__count{font:600 12px var(--font-mono);color:var(--ink-3)}.part__meta{align-items:center;gap:10px;margin-bottom:14px;display:flex}.part__number{font:600 12px var(--font-mono);color:var(--ink-3);letter-spacing:.04em}.part__close{margin-left:auto}.iconbtn{border:1px solid var(--line);cursor:pointer;width:32px;height:32px;color:var(--ink-2);background:#fff;border-radius:50%;font-size:20px;line-height:1}.iconbtn:hover{border-color:var(--ink);color:var(--ink)}.part__title{letter-spacing:-.02em;margin:0;font-size:32px;line-height:1.15}.part__en{font:500 14px var(--font-mono);color:var(--ink-2);letter-spacing:.02em;margin:4px 0 14px}.part__missing{color:var(--ink-2);background:var(--paper-2);border-radius:8px;padding:10px 12px;font-size:14px}.linkbtn{color:var(--accent-ink);cursor:pointer;background:0 0;border:0;padding:0 0 0 6px;font-weight:600;text-decoration:underline}.chip{letter-spacing:.04em;background:var(--paper-2);color:var(--ink-2);border-radius:999px;align-items:center;padding:3px 9px;font-size:12px;font-weight:700;display:inline-flex}.chip--group{color:#fff}.chip--frame{background:var(--g-frame)}.chip--cockpit{background:var(--g-cockpit)}.chip--drivetrain{background:var(--g-drivetrain)}.chip--wheels{background:var(--g-wheels)}.chip--brakes{background:var(--g-brakes)}.chip--contact{background:var(--g-contact)}.chips{flex-wrap:wrap;gap:6px;margin:0;padding:0;list-style:none;display:flex}.chip--tool{border:1px solid var(--line);color:var(--ink);letter-spacing:0;background:#fff;font-size:13px;font-weight:600}.tabs{border-bottom:2px solid var(--line);gap:2px;margin:18px 0 20px;display:flex}.tab{cursor:pointer;color:var(--ink-2);background:0 0;border:0;border-bottom:2px solid #0000;margin-bottom:-2px;padding:10px 14px;font-size:15px;font-weight:600}.tab:hover{color:var(--ink)}.tab.is-active{color:var(--ink);border-bottom-color:var(--accent)}.prose p{margin:0 0 14px}.facts{grid-template-columns:auto 1fr;gap:6px 18px;margin:0;font-size:15px;display:grid}.facts div{display:contents}.facts dt{color:var(--ink-2);font-weight:600}.facts dd{margin:0}.difficulty{letter-spacing:2px;color:var(--accent);font-size:11px}.steps{counter-reset:step;margin:0;padding-left:0;list-style:none}.steps li{border-top:1px solid var(--line);counter-increment:step;padding:10px 0 10px 44px;position:relative}.steps li:last-child{border-bottom:1px solid var(--line)}.steps li:before{content:counter(step, decimal-leading-zero);font:700 13px var(--font-mono);color:var(--accent-ink);position:absolute;top:12px;left:0}.callout{border-radius:8px;margin-top:18px;padding:12px 14px;font-size:15px}.callout--warn{background:var(--warn-bg);color:var(--warn-ink)}.callout--warn strong{letter-spacing:.08em;text-transform:uppercase;margin-bottom:4px;font-size:12px;display:block}.callout ul{margin:0;padding-left:18px}.issues{gap:10px;margin:0;padding:0;list-style:none;display:grid}.issue{border:1px solid var(--line);border-radius:var(--radius);background:#fff;padding:14px 16px}.issue__symptom{margin:0 0 8px;font-weight:700}.issue dl{grid-template-columns:auto 1fr;gap:4px 14px;margin:0;font-size:15px;display:grid}.issue dl div{display:contents}.issue dt{color:var(--ink-2);white-space:nowrap;font-weight:600}.issue dd{margin:0}.resources{gap:8px;margin:0;padding:0;list-style:none;display:grid}.resource a{color:var(--ink);border:1px solid var(--line);border-radius:var(--radius);background:#fff;grid-template-rows:auto auto;grid-template-columns:auto 1fr;align-items:center;gap:0 12px;padding:12px 14px;text-decoration:none;transition:border-color .12s;display:grid}.resource a:hover{border-color:var(--accent)}.resource__type{font:700 11px var(--font-mono);letter-spacing:.08em;background:var(--paper-2);width:44px;height:44px;color:var(--ink-2);border-radius:8px;grid-row:span 2;place-items:center;display:grid}.resource--video .resource__type{background:var(--accent-soft);color:var(--accent-ink)}.resource__title{font-weight:600}.resource__source{color:var(--ink-2);font-size:13px}.part__nav{border-top:1px solid var(--line);justify-content:space-between;gap:10px;margin-top:36px;padding-top:16px;display:flex}.navbtn{border:1px solid var(--line);cursor:pointer;color:var(--ink-2);background:#fff;border-radius:8px;padding:8px 14px;font-size:14px;font-weight:600}.navbtn:hover{border-color:var(--ink);color:var(--ink)}.credits{color:var(--ink-3);border-top:1px solid var(--line);white-space:nowrap;text-overflow:ellipsis;flex:none;align-items:center;height:28px;padding:0 20px;font-size:12px;display:flex;overflow:hidden}.credits a{color:var(--ink-2)}.debug{font:12px var(--font-mono);color:#fff;white-space:pre-wrap;z-index:3;background:#1c1b19e6;border-radius:6px;max-width:420px;padding:8px 10px;position:absolute;top:46px;left:16px}@media (max-width:900px){body{font-size:16px}.layout{grid-template-rows:52vh 1fr;grid-template-columns:1fr}.stage{border-right:0;border-bottom:1px solid var(--line)}.panel{padding:20px 18px 40px}.part__title,.panel__title{font-size:26px}.brand__sub{display:none}.topbar{gap:8px;padding:0 14px}.textbtn{white-space:nowrap;padding:6px 4px}.legend{grid-template-columns:1fr}}