:root{
  --paper:#F3EADA; --surface:#FBF6EC; --sunk:#EBDFCB; --ink:#1F1B15; --muted:#5B5346; --line:#DDCFB8;
  --rust:#A3481A; --rust-ink:#7C3512; --rust-soft:#EDD9C4; --band:#1F1B15; --band-ink:#F3EADA; --band-muted:#C9BEAA; --band-line:#3A3329;
  --up:#2E6B47; --down:#B0281E; --focus:#2B5EA8;
  --display:'Source Serif 4','Noto Serif TC',Georgia,serif;
  --body:'IBM Plex Sans','Noto Sans TC',system-ui,sans-serif;
  --mono:'IBM Plex Mono',ui-monospace,Menlo,monospace;
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --paper:#17140F; --surface:#211D17; --sunk:#2A251D; --ink:#EFE6D6; --muted:#B5AA97; --line:#3A3329;
  --rust:#E08A5A; --rust-ink:#F0A77E; --rust-soft:#3A2618; --band:#0E0C09; --band-ink:#EFE6D6; --band-muted:#B5AA97; --band-line:#332D24;
  --up:#6CC08E; --down:#F07B70; --focus:#8AB4F0; color-scheme:dark}}
:root[data-theme="dark"]{
  --paper:#17140F; --surface:#211D17; --sunk:#2A251D; --ink:#EFE6D6; --muted:#B5AA97; --line:#3A3329;
  --rust:#E08A5A; --rust-ink:#F0A77E; --rust-soft:#3A2618; --band:#0E0C09; --band-ink:#EFE6D6; --band-muted:#B5AA97; --band-line:#332D24;
  --up:#6CC08E; --down:#F07B70; --focus:#8AB4F0; color-scheme:dark}
html[data-lang="en"] .zh, html[data-lang="zh"] .en{display:none!important}
*{box-sizing:border-box}
body{background:var(--paper);color:var(--ink);font-family:var(--body);font-size:16px;line-height:1.6;
  background-image:repeating-linear-gradient(90deg,color-mix(in srgb,var(--ink) 4%,transparent) 0 1px,transparent 1px 96px)}
body::before{content:"";position:fixed;inset:0 0 auto;height:env(safe-area-inset-top,0px);z-index:10;background:var(--paper)}
a{color:var(--rust)} a:hover{color:var(--rust-ink)}
:focus-visible{outline:3px solid var(--focus);outline-offset:2px;border-radius:6px}
h1,h2,h3{font-family:var(--display);text-wrap:balance;margin:0;line-height:1.15}
h1{font-size:clamp(40px,6vw,64px);font-weight:700;letter-spacing:-.01em}
h2{font-size:clamp(28px,3.4vw,38px);font-weight:700}
h3{font-size:22px;font-weight:600}
p{margin:0}
.mono,.num{font-family:var(--mono);font-variant-numeric:tabular-nums}
.wrap{max-width:1120px;margin:0 auto;padding-left:max(16px,env(safe-area-inset-left,0px));padding-right:max(16px,env(safe-area-inset-right,0px))}
.lead{font-size:19px;color:var(--muted);max-width:62ch}
.eyebrow{font-size:12px;font-weight:600;letter-spacing:.08em;text-transform:uppercase;color:var(--rust)}
.stack{display:flex;flex-direction:column;gap:16px}
.row{display:flex;flex-wrap:wrap;gap:16px;align-items:center}
.grid{display:grid;gap:16px}
.g2{grid-template-columns:repeat(auto-fit,minmax(min(100%,300px),1fr))}
.g3{grid-template-columns:repeat(auto-fit,minmax(min(100%,240px),1fr))}
.section{padding-block:72px}
.card{background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:22px;min-width:0}
.chip{display:inline-flex;align-items:center;gap:6px;font-size:12px;font-weight:600;letter-spacing:.04em;padding:3px 10px;border-radius:999px;background:var(--rust-soft);color:var(--rust-ink)}
.chip.ok{background:color-mix(in srgb,var(--up) 16%,transparent);color:var(--up)}
.chip.warn{background:color-mix(in srgb,var(--down) 14%,transparent);color:var(--down)}
.chip.flat{background:var(--sunk);color:var(--muted)}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:46px;padding:0 20px;border-radius:999px;font:600 15px var(--body);border:1px solid transparent;cursor:pointer;text-decoration:none}
.btn.primary{background:var(--rust);color:#fff}.btn.primary:hover{background:var(--rust-ink);color:#fff}
.btn.ghost{background:transparent;border-color:var(--ink);color:var(--ink)}.btn.ghost:hover{background:var(--ink);color:var(--paper)}
.btn.small{min-height:36px;padding:0 14px;font-size:13px}
         
.navbar{position:sticky;top:env(safe-area-inset-top,0px);z-index:20;padding-block:14px 0}
.nav{display:flex;align-items:center;gap:4px;flex-wrap:wrap;background:var(--band);color:var(--band-ink);border-radius:999px;padding:7px 8px 7px 10px;box-shadow:0 10px 30px rgba(0,0,0,.18)}
.brand{display:flex;align-items:center;gap:10px;margin-right:auto;color:var(--band-ink);text-decoration:none;background:none;border:0;cursor:pointer;font:inherit}
.brand img{width:38px;height:38px;border-radius:50%}
.brand b{font-family:var(--display);font-size:19px}
.nav button.nl{background:none;border:0;color:var(--band-muted);font:500 15px var(--body);padding:9px 12px;border-radius:999px;cursor:pointer;min-height:40px}
.nav button.nl:hover,.nav button.nl[aria-current="page"]{color:var(--band-ink);background:var(--band-line)}
.lang{display:flex;border:1px solid var(--band-line);border-radius:999px;overflow:hidden;margin:0 4px}
.lang button{background:none;border:0;color:var(--band-muted);font:600 13px var(--body);padding:8px 11px;cursor:pointer;min-height:36px}
.lang button[aria-pressed="true"]{background:var(--band-ink);color:var(--band)}
@media (max-width:860px){.nav .nl{display:none}.nav .menu-btn{display:inline-flex!important}.nav.open .nl{display:block;width:100%;text-align:left}}
.menu-btn{display:none!important}
          
.band{background:var(--band);color:var(--band-ink);border-radius:26px;padding:44px}
.band .lead{color:var(--band-muted)}
.band .card{background:transparent;border-color:var(--band-line);color:var(--band-ink)}
.band .card p{color:var(--band-muted)}
@media (max-width:600px){.band{padding:26px;border-radius:20px}}
            
.tbl{overflow-x:auto;border:1px solid var(--line);border-radius:12px;background:var(--surface)}
table{border-collapse:collapse;width:100%;font-size:14px}
th,td{padding:10px 14px;text-align:left;border-bottom:1px solid var(--line);vertical-align:top}
th{font-size:12px;letter-spacing:.04em;text-transform:uppercase;color:var(--muted);font-weight:600;background:var(--sunk)}
tr:last-child td{border-bottom:0}
td.r,th.r{text-align:right}
.up{color:var(--up)}.down{color:var(--down)}
                      
details.method{border:1px dashed var(--line);border-radius:12px;padding:0 16px;background:color-mix(in srgb,var(--surface) 70%,transparent)}
details.method summary{cursor:pointer;padding:12px 0;font-weight:600;font-size:14px;color:var(--muted);list-style:none}
details.method summary::before{content:"ƒ  ";font-family:var(--display);font-style:italic;color:var(--rust)}
details.method[open]{padding-bottom:16px}
.formula{font-family:var(--display);font-style:italic;font-size:21px;padding:12px 0;overflow-x:auto;white-space:nowrap}
.formula sub,.formula sup{font-size:.62em}
.vars{font-size:14px;color:var(--muted);display:grid;grid-template-columns:auto 1fr;gap:4px 14px}
.vars b{font-family:var(--display);font-style:italic;color:var(--ink);font-weight:400}
          
.stat{background:var(--sunk);border-radius:10px;padding:12px 14px;min-width:0}
.stat .k{font-size:12px;color:var(--muted)}
.stat .v{font-family:var(--mono);font-size:20px;font-variant-numeric:tabular-nums}
.stat .s{font-size:12px;color:var(--muted)}
                
.copy{display:flex;gap:8px;align-items:stretch;background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:6px 6px 6px 14px}
.copy code{flex:1;min-width:0;font-family:var(--mono);font-size:15px;align-self:center;overflow-x:auto;white-space:nowrap}
          
.tabs{display:flex;gap:6px;flex-wrap:wrap;border-bottom:1px solid var(--line);padding-bottom:10px}
.tabs button{background:none;border:1px solid var(--line);color:var(--ink);border-radius:999px;padding:8px 16px;font:500 14px var(--body);cursor:pointer;min-height:40px;display:inline-flex;align-items:center;gap:8px}
.tabs button[aria-selected="true"]{background:var(--ink);color:var(--paper);border-color:var(--ink)}
.mark{width:22px;height:22px;border-radius:6px;display:inline-grid;place-items:center;font:700 11px var(--body);background:var(--sunk);color:var(--ink)}
.steps{counter-reset:s;list-style:none;padding:0;margin:0;display:grid;gap:12px}
.steps li{counter-increment:s;display:grid;grid-template-columns:34px 1fr;gap:12px;align-items:start}
.steps li::before{content:counter(s);width:30px;height:30px;border-radius:50%;background:var(--rust);color:#fff;display:grid;place-items:center;font:600 14px var(--body)}
                  
.bench{display:flex;flex-wrap:wrap;gap:24px;align-items:flex-start}
.bench aside{flex:1 1 220px;display:grid;gap:6px}
.bench aside button{text-align:left;background:none;border:1px solid transparent;border-radius:10px;padding:10px 12px;font:500 15px var(--body);color:var(--ink);cursor:pointer;display:flex;justify-content:space-between;gap:8px;min-height:44px}
.bench aside button[aria-current="true"]{background:var(--surface);border-color:var(--line)}
.bench .main{flex:999 1 560px;min-width:0}
.bar{height:10px;border-radius:999px;background:var(--sunk);overflow:hidden}
.bar i{display:block;height:100%;background:var(--rust);border-radius:999px}
.toggle{display:flex;justify-content:space-between;align-items:center;gap:12px;padding:12px 0;border-bottom:1px solid var(--line)}
.toggle:last-child{border-bottom:0}
input[type=checkbox].sw{appearance:none;width:44px;height:26px;border-radius:999px;background:var(--sunk);position:relative;cursor:pointer;flex:none;border:1px solid var(--line)}
input[type=checkbox].sw::after{content:"";position:absolute;top:2px;left:2px;width:20px;height:20px;border-radius:50%;background:var(--surface);transition:left .15s}
input[type=checkbox].sw:checked{background:var(--rust)}
input[type=checkbox].sw:checked::after{left:20px}
input[type=text]{font:15px var(--mono);padding:12px 14px;border-radius:10px;border:1px solid var(--line);background:var(--surface);color:var(--ink);min-height:46px;flex:1;min-width:0}
.price{font-family:var(--display);font-size:46px;font-weight:700}
.strike{text-decoration:line-through;color:var(--muted);font-family:var(--mono);font-size:16px}
footer{border-top:1px solid var(--line);margin-top:56px;padding-block:40px 56px;font-size:14px}
.disc{font-size:13px;color:var(--muted);max-width:70ch}
.toast{position:fixed;left:50%;bottom:calc(24px + env(safe-area-inset-bottom,0px));transform:translateX(-50%);background:var(--ink);color:var(--paper);padding:10px 18px;border-radius:999px;font-size:14px;z-index:30}
.view{display:none}.view.on{display:block}
@media (prefers-reduced-motion: reduce){*{transition:none!important}}
.note-proto{font-size:12px;color:var(--muted);border:1px dashed var(--line);border-radius:8px;padding:6px 10px;display:inline-block}