:root{--ink:#242424;--accent:#ad380d;--paper:#f8f4ed;--line:#d7d1c8;--muted:#615b54;--reading:17px}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font:16px/1.55 system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}header{display:flex;gap:18px;align-items:center;max-width:900px;margin:auto;padding:18px 24px 12px;padding-top:max(18px,env(safe-area-inset-top))}header img{object-fit:contain;width:82px;height:58px}header strong{display:block;font-size:15px;letter-spacing:2px}header span{font-size:12px;color:var(--muted)}.edition{background:var(--ink);color:#fff;text-align:center;font-size:11px;letter-spacing:.8px;padding:7px 12px}main{max-width:860px;margin:auto;padding:30px 22px calc(110px + env(safe-area-inset-bottom))}h1{font-size:clamp(32px,7vw,48px);line-height:1.05;letter-spacing:-1.5px;margin:12px 0 20px}h2{font-size:24px;line-height:1.2;margin:0 0 14px}h3{font-size:19px;line-height:1.3;margin:24px 0 10px}p{margin:0 0 16px}.eyebrow{color:var(--accent);text-transform:uppercase;letter-spacing:1.7px;font-size:11px;font-weight:750}.intro{color:var(--muted);max-width:540px}.bar{display:flex;gap:12px;flex-wrap:wrap;margin:20px 0}.bar>label{flex:1;min-width:130px}label{display:block;font-size:13px;font-weight:650;margin-bottom:18px}input,select,textarea{display:block;font:inherit;font-weight:400;font-size:16px;min-height:48px;width:100%;border:1px solid #958f88;border-radius:5px;background:#fffdf9;color:var(--ink);padding:10px 12px;margin-top:7px}input:focus,select:focus,textarea:focus,button:focus-visible{outline:3px solid #b9400e;outline-offset:3px}.panel{border:1px solid var(--line);background:#fffdf9;border-radius:9px;padding:26px 24px;margin:25px 0}.fields{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:0 20px}.measure{display:flex;gap:7px}.measure input{width:65%}.measure select{width:35%}.field small{display:block;color:var(--muted);font-size:12px;font-weight:400;margin-top:6px}.example{font-size:12px;color:var(--accent)}button,.file-button{font:inherit;font-size:14px;min-height:46px;border:1px solid var(--line);border-radius:5px;padding:11px 16px;cursor:pointer;background:#fff;color:var(--ink);font-weight:650;margin:0 7px 10px 0}.primary{background:var(--accent);color:#fff;border-color:var(--accent)}.secondary{background:transparent;border-color:#9b948b}.danger{color:#8f1c13;border-color:#a84b44;background:transparent}.error{color:#a32016;font-weight:650}.number{font-size:42px;font-weight:750;line-height:1.12;margin:14px 0 4px;overflow-wrap:anywhere}.unit{font-size:17px;color:var(--muted)}.metric{display:flex;justify-content:space-between;gap:20px;border-bottom:1px solid var(--line);padding:11px 0;font-size:14px}.metric strong{text-align:right}.formula{margin:22px 0 14px;font-size:15px;overflow-wrap:anywhere}.scope{font-size:12px;color:var(--muted);margin-top:24px}ul{padding-left:22px}li{margin:8px 0}#result-actions{margin-top:25px}#result{margin-top:24px}.bottom{position:fixed;bottom:0;left:0;right:0;background:var(--ink);padding:7px 10px max(7px,env(safe-area-inset-bottom));display:flex;justify-content:center;gap:0;z-index:5}.bottom button{background:transparent;border:0;color:#d0cbc4;border-radius:0;font-size:12px;min-width:0;width:25%;max-width:190px;padding:12px 3px;margin:0;min-height:49px}.bottom button[aria-current=page]{color:#fff;border-top:3px solid #f77b47;padding-top:9px}.chapter-button{display:block;text-align:left;width:100%;padding:17px;margin:12px 0;background:#fffdf9}.chapter-button strong{display:block;font-size:17px}.chapter-button span{color:var(--muted);font-size:11px}.check{display:flex;align-items:center;gap:10px}.check input{width:22px;min-height:22px;margin:0}.reading-tools{display:flex;flex-wrap:wrap;gap:7px;margin:20px 0}#chapter-body{font-size:var(--reading);line-height:1.7;overflow-wrap:anywhere}#chapter-body .equation{font-size:1em;font-weight:650;line-height:1.6}#chapter-body figure{margin:22px 0}#chapter-body img{display:block;width:100%;height:auto}table{border-collapse:collapse;width:100%;font-size:13px;margin:20px 0}td,th{padding:10px;text-align:left;border:1px solid var(--line);vertical-align:top}th{background:#eeeae3}.table-scroll{overflow:auto}.saved-record{padding:22px;border:1px solid var(--line);border-radius:7px;background:#fffdf9;margin:20px 0}.saved-record details{font-size:13px;white-space:pre-wrap}.saved-record label{margin-top:16px}.file-button input{font-size:12px;border:0;padding:4px;min-height:24px;background:transparent}.file-button{display:block;background:#fffdf9;font-size:13px}.saved-record h2{font-size:21px}#status{font-size:13px;color:var(--accent);margin:20px 0}dialog{border:1px solid var(--line);border-radius:10px;background:var(--paper);max-width:460px;padding:27px}dialog::backdrop{background:#0008}.skip{position:fixed;left:10px;top:-80px;background:#fff;color:#222;padding:15px;z-index:10}.skip:focus{top:10px}button:disabled{opacity:.45;cursor:default}[hidden]{display:none!important}@media(max-width:520px){main{padding-left:16px;padding-right:16px}.fields{grid-template-columns:1fr}.panel{padding:23px 17px}.metric{font-size:13px}header{padding-left:17px}.bar{gap:8px}.bar>button{flex:1}h1{margin-top:10px}.number{font-size:36px}}@media(prefers-reduced-motion:no-preference){button{transition:background .12s}}@media print{header,.edition,.bottom,.reading-tools,#back-to-chapters,#calc-form,#result-actions,.bar{display:none}main{padding:0;max-width:none}body{background:white}}