/* Engineering Lab. Tokens and type follow the exposé (index.html). */
:root{
  --road-blue:#005387; --road-blue-ink:#00436d; --warn:#F0CA00; --warn-ink:#6b5a00; --hazard:#C1121C; --ok:#1d7a3a;
  --bg:#F5F6F4; --surface:#FFFFFF; --ink:#16191B; --ink-2:#4A5157; --muted:#6b747c; --rule:#D9DDDF; --chip:#E7EEF4;
  --display:"Barlow Condensed","Arial Narrow",Arial,sans-serif; --body:"Barlow","Segoe UI",Arial,sans-serif;
  --mono:ui-monospace,"Cascadia Mono",Consolas,monospace;
  color-scheme:light;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){color-scheme:dark;
    --road-blue:#5AA8E0; --road-blue-ink:#8cc4ec; --warn:#F0CA00; --warn-ink:#F0CA00; --hazard:#FF6B6B; --ok:#5fcf86;
    --bg:#15181A; --surface:#1D2124; --ink:#ECEEEF; --ink-2:#B5BCC1; --muted:#98a0a6; --rule:#30363A; --chip:#22303B;}
}
:root[data-theme="dark"]{color-scheme:dark;
  --road-blue:#5AA8E0; --road-blue-ink:#8cc4ec; --warn:#F0CA00; --warn-ink:#F0CA00; --hazard:#FF6B6B; --ok:#5fcf86;
  --bg:#15181A; --surface:#1D2124; --ink:#ECEEEF; --ink-2:#B5BCC1; --muted:#98a0a6; --rule:#30363A; --chip:#22303B;}

*{box-sizing:border-box}
[hidden]{display:none!important}
body{background:var(--bg);color:var(--ink);font:400 17px/1.6 var(--body);margin:0;padding-inline:clamp(16px,4vw,48px);padding-block:0 64px}
a{color:var(--road-blue)}
:focus-visible{outline:3px solid var(--warn);outline-offset:2px}
.wrap{max-width:1120px;margin:0 auto}
h1,h2,h3{font-family:var(--display);font-weight:700;line-height:1.02;margin:0;text-wrap:balance}
h1{font-size:clamp(46px,7.4vw,88px)}
h2{font-size:clamp(32px,4.4vw,50px)}
h3{font-size:24px;font-weight:600;margin-bottom:10px}
p{margin:0 0 10px;max-width:68ch}
.lead{font-size:clamp(19px,2vw,22px);line-height:1.5;color:var(--ink-2);max-width:58ch}
.small{font-size:14px;color:var(--muted)}
code,pre{font-family:var(--mono);font-size:14px}
pre{background:var(--chip);border-radius:6px;padding:10px 12px;overflow-x:auto;margin:6px 0 12px;white-space:pre}
.skip{position:absolute;left:-999px;top:8px}
.skip:focus{left:16px;z-index:10;background:var(--surface);padding:6px 10px}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}

/* top bar */
.bar{position:sticky;top:0;z-index:5;background:var(--bg);border-bottom:1px solid var(--rule);margin-inline:calc(-1*clamp(16px,4vw,48px));padding:10px clamp(16px,4vw,48px)}
.bar .wrap{display:flex;gap:18px;align-items:center;justify-content:space-between;flex-wrap:wrap}
.brand{display:flex;align-items:center;gap:10px;font:700 20px/1 var(--display);color:var(--ink);text-decoration:none}
.sign{width:30px;height:30px;border-radius:7px;background:var(--road-blue);display:grid;place-items:center}
.sign svg{width:20px;height:20px}
.toc{display:flex;gap:16px;flex-wrap:wrap;font-size:15px}
.toc a{color:var(--ink-2);text-decoration:none}
.toc a:hover{color:var(--road-blue);text-decoration:underline}

/* layout */
.hero{padding-block:clamp(36px,7vw,80px) 24px;display:grid;gap:18px}
.kicker{font:600 20px/1 var(--display);color:var(--road-blue);margin:0}
section{padding-block:clamp(32px,5vw,56px);border-top:1px solid var(--rule)}
.sec-head{display:grid;grid-template-columns:56px 1fr;gap:12px;margin-bottom:22px}
.sec-head p{color:var(--ink-2);margin-top:10px}
.sec-no{font:700 40px/1 var(--display);color:var(--road-blue)}
.grid2{display:grid;grid-template-columns:1fr 1fr;gap:18px}
.panel{background:var(--surface);border:1px solid var(--rule);border-radius:10px;padding:18px 20px}
.actions,.editor-row,.composer-row,.conn-row{display:flex;gap:10px;align-items:center;flex-wrap:wrap}
.actions{margin-bottom:16px}

/* buttons */
.btn{font:600 16px/1 var(--body);background:var(--road-blue);color:#fff;border:2px solid var(--road-blue);border-radius:7px;padding:10px 16px;cursor:pointer;text-decoration:none;display:inline-block}
.btn.ghost{background:transparent;color:var(--road-blue)}
.btn:disabled{opacity:.45;cursor:not-allowed}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]) .btn:not(.ghost){color:#0b1620}}

/* challenge */
.reqs{margin:0;padding-left:0;list-style:none;display:grid;gap:6px}
.reqs b{display:inline-block;min-width:46px;color:var(--road-blue)}
.ref{display:grid;grid-template-columns:auto 1fr;gap:6px 14px;margin:0 0 12px}
.ref dt{font-weight:600}
.ref dd{margin:0;color:var(--ink-2)}
.questions{margin-top:22px}
.questions ul{margin:0 0 12px;padding-left:20px}

/* connection */
.conn{display:grid;gap:12px;margin-bottom:14px}
.status{display:flex;gap:10px;align-items:center;font-weight:600}
.dot{width:12px;height:12px;border-radius:50%;background:var(--muted);flex:none}
.dot.ok{background:var(--ok)} .dot.bad{background:var(--hazard)} .dot.busy{background:var(--warn)}
label{font-weight:600;font-size:15px}
select,input[type=text],textarea{font:inherit;font-size:16px;color:var(--ink);background:var(--bg);border:1px solid var(--rule);border-radius:7px;padding:8px 10px;max-width:100%}
select{min-width:min(260px,100%)}
.adv summary,.setup summary,.os summary{cursor:pointer;font-weight:600}
.adv{font-size:15px} .adv input{width:min(340px,100%);display:block;margin-top:4px}
.help{border-left:4px solid var(--hazard);padding:6px 0 6px 12px}
.help ul{margin:6px 0 0;padding-left:20px}
.setup{margin-bottom:14px;background:var(--surface);border:1px solid var(--rule);border-radius:10px;padding:14px 20px}
.setup-body{margin-top:12px}
.os details{border-top:1px solid var(--rule);padding:8px 0}
.note{border-left:4px solid var(--warn);padding-left:12px}

/* chat */
.chat{display:grid;gap:12px}
.log{min-height:220px;max-height:min(62vh,640px);overflow-y:auto;display:grid;gap:12px;align-content:start;padding-right:4px}
.empty{color:var(--muted);font-style:italic}
.msg{border-radius:10px;padding:10px 14px;max-width:min(78ch,100%);overflow-wrap:anywhere}
.msg p{margin:0 0 8px} .msg p:last-child{margin-bottom:0}
.msg ul,.msg ol{margin:4px 0 8px;padding-left:22px}
.msg .md-h{font-weight:700}
.msg.user{background:var(--chip);justify-self:end}
.msg.assistant{background:var(--bg);border:1px solid var(--rule)}
.msg.error{border:1px solid var(--hazard);color:var(--hazard)}
.who{font-size:13px;color:var(--muted);margin-bottom:4px;display:block}
.composer{display:grid;gap:8px}
.composer textarea{width:100%;resize:vertical}
.composer-row{justify-content:flex-end}
#chat-note{margin-right:auto}

/* proposal editor */
.editor{display:grid;gap:6px}
.editor input[type=text]{width:100%;margin-bottom:10px}
.editor textarea{width:100%;resize:vertical;margin-bottom:10px}
.field-hint{font-size:14px;color:var(--muted);font-weight:400;display:block}
.req{color:var(--hazard);font-weight:600}
.opt{color:var(--muted);font-weight:400;font-size:14px}
.ai-row{display:flex;gap:12px;align-items:center;flex-wrap:wrap;margin:2px 0 12px}
.review{border:1px solid var(--rule);border-radius:8px;padding:10px 14px;margin-bottom:12px;background:var(--bg)}
.review summary{cursor:pointer;font-weight:600}
.review textarea{font-family:var(--mono);font-size:14px;background:var(--surface)}
dialog input[type=text]{width:100%;margin:4px 0 6px}
.invalid{border-color:var(--hazard)!important}
.editor-row{margin-top:6px}

/* dialog */
dialog{border:1px solid var(--rule);border-radius:12px;background:var(--surface);color:var(--ink);max-width:min(560px,calc(100vw - 32px));padding:22px 24px}
dialog::backdrop{background:rgba(0,0,0,.45)}
dialog h2{font-size:32px;margin-bottom:12px}
dialog ul{padding-left:20px}
.check{display:flex;gap:10px;align-items:flex-start;font-weight:600;margin:12px 0}
.check input{width:20px;height:20px;margin-top:3px}

.disclaimer{margin-top:28px;font-size:14px;color:var(--muted);border-top:1px solid var(--rule);padding-top:14px;max-width:none}
#giscus-slot iframe{width:100%}

@media (max-width:760px){
  .grid2{grid-template-columns:1fr}
  .sec-head{grid-template-columns:1fr}
  .toc{gap:12px;font-size:14px}
  .composer-row .btn{flex:1 1 auto}
}
@media (prefers-reduced-motion: reduce){*{scroll-behavior:auto!important}}