@font-face{font-family:"Source Serif 4";src:url(fonts/source-serif-4-normal-latin-ext.woff2) format("woff2");font-weight:400 700;font-display:swap;unicode-range:U+0100-02BA,U+02BD-02C5,U+02C7-02CC,U+02CE-02D7,U+02DD-02FF,U+0304,U+0308,U+0329,U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF}
@font-face{font-family:"Source Serif 4";src:url(fonts/source-serif-4-normal-latin.woff2) format("woff2");font-weight:400 700;font-display:swap;unicode-range:U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD}
@font-face{font-family:"IBM Plex Sans";src:url(fonts/IBMPlexSans-latin-ext.woff2) format("woff2");font-weight:400 700;font-display:swap;unicode-range:U+0100-02BA,U+02BD-02C5,U+02C7-02CC,U+02CE-02D7,U+02DD-02FF,U+0304,U+0308,U+0329,U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF}
@font-face{font-family:"IBM Plex Sans";src:url(fonts/IBMPlexSans-latin.woff2) format("woff2");font-weight:400 700;font-display:swap;unicode-range:U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD}
:root{
  --bg:#f7f1e5; --ink:#2b2016; --mut:#77634c; --accent:#a06028; --line:#e0cfae;
  --card:#fffaf0; --bark:#5d4630; --wood0:#c49866; --wood1:#dbbc94; --wood2:#a8763e;
  --board:#c99a5e; --board-on:#a06028; --ghost:#b9a888;
  --o-line:#5a3f26; --o-lit:#ecd2ac; --o-wood:#d4a877; --o-shade:#a97a4c; --o-end:#ecd0a9; --o-ring:#c4925f;
  --o-bark:#a39a8c; --o-barklit:#d2c8b8; --o-barkdot:#776d60; --o-mdf:#c9a57a; --o-mdfedge:#b48c60; --o-mdfside:#9c7650;
  --o-osb:#d8b47c; --o-osbedge:#c09a64; --o-osbside:#a3804f; --o-osbflake:#b0844e; --o-white:#f6f3ec; --o-whiteside:#d9d3c6; --o-shine:#ffffff;
  --o-paint:#dcc29c; --o-metal:#6e6e6a; --o-ply:#b68757; --o-cloth:#eae3d4; --o-fabric:#b9925e; --o-fabriclit:#d3b07e; --o-fabricdk:#93703f; --o-strap:#3f4a57; --o-lam:#cdb08a;
  --pl-top:#f0d6b0; --pl:#d7ab78; --pl-low:#b5834f; --pl-grain:rgba(122,74,34,.16); --end:#efd4ae;
  --hero-top:#e9a865; --hero:#c47a3a; --hero-low:#94561f; --wall:#efe5d2;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#171208; --ink:#f0e4cd; --mut:#c6af8c; --accent:#dd9a4e; --line:#3a2c1b;
  --card:#211709; --bark:#8a6a48; --board:#9a7038; --board-on:#dd9a4e; --ghost:#6e5a40;
  --o-line:#20150a; --o-lit:#dcbb8f; --o-wood:#c29a69; --o-shade:#93693f; --o-end:#d8b78c; --o-ring:#a87b4c;
  --o-bark:#5b544a; --o-barklit:#7f766a; --o-barkdot:#3a352f; --o-mdf:#a78659; --o-mdfedge:#8f6e48; --o-mdfside:#75583a;
  --o-osb:#b4925f; --o-osbedge:#9c7c4c; --o-osbside:#80653e; --o-osbflake:#8a693d; --o-white:#bdb7ab; --o-whiteside:#948e82; --o-shine:#efece5;
  --o-paint:#bfa47e; --o-metal:#9a9a94; --o-ply:#8f6a42; --o-cloth:#c9c2b3; --o-fabric:#a7845a; --o-fabriclit:#c4a273; --o-fabricdk:#7f6040; --o-strap:#2a323b; --o-lam:#a88f6c;
  --pl-top:#e2c08f; --pl:#a8804f; --pl-low:#6c4b2a; --pl-grain:rgba(30,18,6,.22); --end:#c9a87e;
  --hero-top:#f0ad66; --hero:#c97c38; --hero-low:#8a4f1c; --wall:#1d160c; --tickc:#e8cfa6;
}}
:root[data-theme="dark"]{
  --bg:#171208; --ink:#f0e4cd; --mut:#c6af8c; --accent:#dd9a4e; --line:#3a2c1b;
  --card:#211709; --bark:#8a6a48; --board:#9a7038; --board-on:#dd9a4e; --ghost:#6e5a40;
  --o-line:#20150a; --o-lit:#dcbb8f; --o-wood:#c29a69; --o-shade:#93693f; --o-end:#d8b78c; --o-ring:#a87b4c;
  --o-bark:#5b544a; --o-barklit:#7f766a; --o-barkdot:#3a352f; --o-mdf:#a78659; --o-mdfedge:#8f6e48; --o-mdfside:#75583a;
  --o-osb:#b4925f; --o-osbedge:#9c7c4c; --o-osbside:#80653e; --o-osbflake:#8a693d; --o-white:#bdb7ab; --o-whiteside:#948e82; --o-shine:#efece5;
  --o-paint:#bfa47e; --o-metal:#9a9a94; --o-ply:#8f6a42; --o-cloth:#c9c2b3; --o-fabric:#a7845a; --o-fabriclit:#c4a273; --o-fabricdk:#7f6040; --o-strap:#2a323b; --o-lam:#a88f6c;
  --pl-top:#e2c08f; --pl:#a8804f; --pl-low:#6c4b2a; --pl-grain:rgba(30,18,6,.22); --end:#c9a87e;
  --hero-top:#f0ad66; --hero:#c97c38; --hero-low:#8a4f1c; --wall:#1d160c; --tickc:#e8cfa6;
}
*{box-sizing:border-box}
[hidden],.rung[hidden],.detail[hidden]{display:none!important}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font-family:"IBM Plex Sans",system-ui,-apple-system,"Segoe UI",sans-serif;font-size:17px;line-height:1.55}
h1,h2,h3{font-family:"Source Serif 4",Georgia,"Times New Roman",serif;line-height:1.12;margin:0 0 .5em}
h1{font-size:clamp(2.4rem,7vw,4rem);letter-spacing:-.01em}
h2{font-size:clamp(1.55rem,4.4vw,2.15rem);margin-top:0}
h3{font-size:1.18rem}
p{max-width:66ch}
a{color:var(--accent)}
main, .site-footer{max-width:1060px;margin:0 auto;padding:0 18px}
section{padding:44px 0 8px;scroll-margin-top:76px}
.skip-link{position:absolute;left:-999px;top:0;background:var(--ink);color:var(--bg);padding:8px 14px;z-index:60}
.skip-link:focus{left:8px;top:8px}
.rail{position:fixed;top:0;left:0;right:0;height:3px;z-index:55;background:transparent}
.rail span{display:block;height:100%;width:0;background:var(--accent)}
.topbar{position:sticky;top:0;z-index:50;display:flex;align-items:center;gap:10px;background:var(--bg);border-bottom:1px solid var(--line);padding:9px 18px;max-width:1060px;margin:0 auto}
.brand{display:flex;align-items:center;gap:9px;color:var(--ink);text-decoration:none;font-family:"Source Serif 4",Georgia,serif;font-weight:700;font-size:1.02rem;white-space:nowrap}
.brand-mark{width:20px;height:20px;border-radius:50%;background:radial-gradient(circle,var(--wood0) 0 22%,var(--wood1) 23% 45%,var(--wood2) 46% 65%,var(--wood1) 66% 84%,var(--bark) 85%)}
.topnav{display:flex;gap:14px;overflow-x:auto;scrollbar-width:none}
.topnav a{color:var(--mut);text-decoration:none;font-size:.86rem;white-space:nowrap}
.topnav a:hover{color:var(--ink)}
.spacer{flex:1}
.chip{border:1px solid var(--line);border-radius:999px;padding:3px 10px;font-size:.8rem;color:var(--mut);text-decoration:none}
.chip[aria-current="page"]{background:var(--ink);color:var(--bg);border-color:var(--ink)}
.icon-btn{background:none;border:1px solid var(--line);border-radius:999px;width:32px;height:32px;display:grid;place-items:center;color:var(--ink);cursor:pointer}
.kicker{color:var(--accent);font-size:.85rem;font-weight:600;letter-spacing:.06em;text-transform:uppercase;margin:0 0 12px}
.deck{font-size:1.16rem;max-width:62ch}
figcaption{color:var(--mut);font-size:.85rem;max-width:60ch}
.sub{color:var(--mut);margin-top:-4px}
.axis{display:flex;justify-content:center;color:var(--mut);font-size:.78rem;margin:14px 100px 0 44px;max-width:none}
@media(max-width:560px){.axis{margin:2px 70px 0 60px}}
.detail{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:18px 18px 10px;margin-top:16px}
.detail p{margin:.35em 0;font-size:.94rem}
.d-bars{display:grid;gap:6px;margin:10px 0}
.d-row{display:grid;grid-template-columns:64px 1fr;gap:10px;align-items:center;font-size:.85rem;color:var(--mut)}
.d-track{height:14px;background:color-mix(in srgb,var(--line) 45%,transparent);border-radius:4px;overflow:hidden}
.d-board{display:block;height:100%;width:var(--w);min-width:2px}
.d-board.exp{background:var(--board-on)} .d-board.imp{background:var(--ghost)}
.d-flow{color:var(--mut);font-size:.92rem}
.objs{display:flex;flex-wrap:wrap;gap:9px;margin-top:14px}
.obj{display:flex;align-items:center;gap:8px;border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:999px;padding:8px 14px;cursor:pointer;font:inherit;font-size:.92rem}
.obj svg{color:var(--accent)}
.obj.on{background:var(--ink);color:var(--bg);border-color:var(--ink)}
.obj.on svg{color:var(--bg)}
.r-ratio{font-family:"Source Serif 4",Georgia,serif;font-size:1.12rem;color:var(--accent);margin:.1em 0 .4em}
.share-row{display:flex;align-items:center;gap:12px;margin-top:14px}
.btn{background:var(--accent);color:#fff;border:0;border-radius:999px;padding:9px 18px;font:inherit;font-size:.92rem;cursor:pointer}
.share-hint{color:var(--mut);font-size:.88rem}
.cards{display:grid;gap:14px;margin-top:16px}
@media(min-width:820px){.cards{grid-template-columns:repeat(3,1fr)}}
.card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:18px}
.card p{margin:0;font-size:.97rem}
figure{margin:20px 0}
.chart{width:100%;height:auto;display:block}
.clab{fill:var(--mut);font-size:13px;font-family:"IBM Plex Sans",system-ui,sans-serif}
.clab.b{fill:var(--ink);font-weight:600}
.site-footer{display:flex;flex-wrap:wrap;gap:10px 22px;border-top:1px solid var(--line);padding:22px 18px 40px;margin-top:52px;color:var(--mut);font-size:.9rem}
.site-footer a{color:var(--mut)}
@media(max-width:560px){
  .topnav{display:none}
  .deck{font-size:1.06rem}
}
.hero{padding:30px 0 0}
.hero h1{margin-bottom:.25em}
.scara{padding-top:22px}
.scara h2{font-size:clamp(1.3rem,3.6vw,1.75rem)}
.legend{display:flex;flex-wrap:wrap;gap:6px 18px;color:var(--mut);font-size:.8rem;margin:6px 0 4px;max-width:none}
.legend span{display:inline-flex;align-items:center;gap:7px}
.legend i{display:inline-block;flex:none}
.lg-len{width:30px;height:7px;border-radius:1px;background:linear-gradient(180deg,var(--pl-top),var(--pl) 40%,var(--pl-low))}
.lg-thick{width:22px;height:14px;background:linear-gradient(180deg,var(--pl-top),var(--pl) 40%,var(--pl-low)) 0 0/9px 14px no-repeat,linear-gradient(180deg,var(--pl-top),var(--pl) 40%,var(--pl-low)) 13px 10px/9px 4px no-repeat}
.lg-ghost{width:22px;height:9px;border:1.4px dashed var(--mut);border-left:0}
.lg-imp{width:0;height:0;border:5px solid transparent;border-bottom:7px solid var(--mut);border-top:0;margin:0 4px}
/* drawn ladder: a beech trunk with boards for branches */
.ladder{--trunk:46px;--res:100px;--br:46px;position:relative;display:grid;gap:2px;margin-top:26px;padding:6px 0 44px calc(var(--trunk) - 3px)}
.trunk{position:absolute;left:0;top:8px;bottom:14px;width:var(--trunk);clip-path:polygon(9% 0,91% 0,100% 100%,0 100%);
  background:linear-gradient(90deg,var(--o-bark) 0,var(--o-barklit) 20%,var(--o-bark) 52%,var(--o-barkdot) 90%,var(--o-bark) 100%);
  box-shadow:inset -4px 0 6px rgba(0,0,0,.2)}
.trunk::before{content:"";position:absolute;inset:0;background:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='46' height='211' viewBox='0 0 46 211'%3E%3Cg fill='#fff' opacity='.2'%3E%3Cellipse cx='14' cy='30' rx='9' ry='16'/%3E%3Cellipse cx='30' cy='118' rx='7' ry='20'/%3E%3Cellipse cx='12' cy='168' rx='6' ry='12'/%3E%3C/g%3E%3Cg fill='#000' opacity='.17'%3E%3Cellipse cx='34' cy='60' rx='8' ry='14'/%3E%3Cellipse cx='18' cy='96' rx='6' ry='10'/%3E%3Cellipse cx='33' cy='190' rx='7' ry='13'/%3E%3C/g%3E%3Cg fill='none' stroke='#000' stroke-linecap='round' opacity='.6'%3E%3Cpath d='M14 78q8 5 16 0' stroke-width='2.2'/%3E%3Cpath d='M11 72q11-6 22 0' stroke-width='1.2' opacity='.7'/%3E%3C/g%3E%3Cg fill='none' stroke='#000' stroke-linecap='round' opacity='.48'%3E%3Cpath d='M24 150q5 3 10 0' stroke-width='1.6'/%3E%3Cpath d='M22 146q7-4 14 0' stroke-width='.9'/%3E%3C/g%3E%3Cg stroke='#000' stroke-linecap='round' opacity='.32' stroke-width='1'%3E%3Cpath d='M9 14h5M27 41h6M16 124h4M30 99h5M8 199h5M22 182h4'/%3E%3C/g%3E%3Cg stroke='#fff' stroke-linecap='round' opacity='.32' stroke-width='1'%3E%3Cpath d='M10 52h4M21 133h5M12 110h3'/%3E%3C/g%3E%3C/svg%3E") 0 0/100% 211px repeat-y}
.ladder::after{content:"";position:absolute;left:-12px;width:110px;bottom:7px;height:14px;z-index:-1;border-radius:50%;background:radial-gradient(ellipse at 35% 40%,rgba(90,60,30,.32),transparent 70%)}
.trunk-cap{position:absolute;left:-2px;top:-15px;width:calc(var(--trunk) + 4px);height:auto;filter:drop-shadow(0 2px 2px rgba(60,35,15,.25))}
.rung{position:relative;display:block;width:100%;text-align:left;background:none;border:0;border-radius:10px;padding:2px 0 10px;cursor:pointer;color:var(--ink);font:inherit;font-size:.9rem}
.rung:focus-visible,.obj:focus-visible,.btn:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.band{display:grid;align-items:end;min-height:34px;grid-template-columns:var(--br) 1fr;padding-left:4px}
.obj-d{width:44px;height:33px;display:block;grid-column:1;grid-row:1;filter:drop-shadow(0 1.5px 0 rgba(60,35,15,.18));transition:transform .2s}
.r-name{grid-row:1;grid-column:2;padding-left:9px;display:flex;flex-direction:column;line-height:1.18;min-width:0;padding-bottom:3px}
.r-name{text-shadow:0 0 3px var(--bg),0 0 3px var(--bg),0 0 2px var(--bg)}
.r-name small{color:var(--mut);font-size:.74rem;margin-top:1px}
.is-hero .r-name{font-weight:600;color:var(--accent)}
.tag{text-shadow:none;display:inline-block;align-self:flex-start;margin:2px 0 1px;padding:1px 7px;border-radius:999px;background:var(--accent);color:var(--bg);font-size:.72rem;font-weight:600;letter-spacing:.02em}
.pl-line{position:relative;display:block;height:calc(var(--t) * 1px);min-height:3px;padding-right:var(--res);margin-left:var(--br)}
.pl-line::before{content:"";position:absolute;right:calc(100% - 2px);width:calc(var(--br) + 6px);top:50%;height:max(5px,calc(var(--t) * .62px));transform:translateY(-50%);background:linear-gradient(180deg,var(--o-barklit),var(--o-bark) 55%,var(--o-barkdot));clip-path:polygon(0 0,100% 22%,100% 78%,0 100%)}
.plank{position:relative;z-index:1;display:block;height:100%;width:calc(var(--w) * 1%);border-radius:1px 2px 2px 1px;
  background:repeating-linear-gradient(180deg,transparent 0 3px,var(--pl-grain) 3px 4px,transparent 4px 7px),
    linear-gradient(180deg,var(--pl-top) 0,var(--pl) 35%,var(--pl-low) 100%);
  box-shadow:0 3px 3px -1px rgba(60,35,15,.3),inset -4px 0 0 var(--end),inset 0 1.5px 0 rgba(255,245,225,.45)}
.plank::before{content:"";position:absolute;left:0;top:0;bottom:0;width:10px;background:linear-gradient(90deg,rgba(40,25,10,.38),transparent)}
.is-hero .plank{box-shadow:0 4px 5px -1px rgba(120,60,10,.4),inset -4px 0 0 var(--end);background:repeating-linear-gradient(180deg,transparent 0 3px,var(--pl-grain) 3px 4px,transparent 4px 7px),
    linear-gradient(180deg,var(--hero-top) 0,var(--hero) 40%,var(--hero-low) 100%)}
.ghost{position:absolute;left:0;top:0;height:100%;min-height:3px;width:calc((100% - var(--res)) * var(--wi) / 100);border:1.4px dashed var(--mut);border-left:0;border-radius:2px;opacity:.85}
.tick{position:absolute;z-index:2;top:calc(100% + 1px);left:calc((100% - var(--res)) * var(--wi) / 100 - 5px);width:0;height:0;border:5px solid transparent;border-bottom:7px solid var(--mut);border-top:0}
.r-val{position:absolute;top:50%;transform:translateY(-50%);left:calc((100% - var(--res)) * var(--wv) / 100 + 10px);font-variant-numeric:tabular-nums;font-weight:600;white-space:nowrap;font-size:.86rem}
.rung:hover .obj-d,.rung[aria-expanded="true"] .obj-d{transform:translateY(-2px)}
.rung:hover .plank{filter:brightness(1.06)}
.rung[aria-expanded="true"] .plank{transform:translateY(-2px);box-shadow:0 7px 8px -2px rgba(60,35,15,.45),inset -4px 0 0 var(--end)}
.rung[aria-expanded="true"] .r-name{color:var(--accent)}
.grid{position:absolute;left:calc(var(--trunk) - 3px + var(--br));right:0;top:0;bottom:6px;padding-right:var(--res);pointer-events:none;bottom:28px}
.gl{position:absolute;top:10px;bottom:0;left:calc((100% - var(--res)) * var(--g) / 100);border-left:1px dashed color-mix(in srgb,var(--line) 70%,transparent)}
.gl b{position:absolute;bottom:-20px;left:0;transform:translateX(-50%);font-weight:500;font-size:.78rem;color:var(--mut);white-space:nowrap}
.rung{z-index:1}
.tree{position:absolute;left:0;top:0;pointer-events:none;overflow:visible;z-index:0}
.tree-on .trunk,.tree-on .trunk-cap{visibility:hidden}
.tree-on .pl-line::before{display:none}
.ladder .detail{margin:2px 0 14px var(--br);position:relative;z-index:3}
.d-note{font-size:.92rem;color:var(--ink);border-left:3px solid var(--accent);padding-left:10px}
.d-note:empty{display:none}
.read{margin-top:18px}
.note{color:var(--mut);font-size:.92rem}
.reader .r-head{display:flex;align-items:center;gap:14px}
.reader .r-head h3{margin:0}
.reader .r-head>div{flex:1;min-width:0}
.obj-big{width:84px;height:63px;flex:none;display:block}
.obj-sm{width:28px;height:21px;flex:none}
.china{margin:14px 0 0}
.china svg{width:100%;max-width:300px;height:auto;display:block}
.china figcaption{margin-top:6px}
.price-txt{display:flow-root}
.rings-fig{float:right;width:150px;margin:4px 0 10px 20px;text-align:center}
.rings{width:150px;height:auto}
.rings-fig figcaption{font-size:.78rem}
@media(max-width:560px){
  .gl b{font-size:.74rem}
  .rung{padding-bottom:14px}
  .ladder{padding-bottom:40px}
  .reader .r-head{flex-direction:column;align-items:flex-start;gap:6px}
  .ladder{--trunk:30px;--res:70px;--br:38px}
  .band{grid-template-columns:var(--br) 1fr;min-height:30px;padding-left:2px}
  .pl-line{height:calc(var(--t) * .72px)}
  .obj-d{width:36px;height:27px}
  .rung{font-size:.84rem}
  .r-val{font-size:.8rem;left:calc((100% - var(--res)) * var(--wv) / 100 + 12px)}
  .gl-odd b{display:none}
  .rings-fig{width:110px;margin-left:12px}.rings{width:110px}
  .legend{gap:4px 14px;font-size:.76rem}
  .hero{padding-top:22px}
}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.obj-d{transition:none}}