:root{--bg:#f5f7fb;--card:#fff;--soft:#edf3fa;--text:#172033;--muted:#687388;--border:#dce2eb;--blue:#17365d;--input:#fff;--shadow:0 8px 24px rgba(24,49,83,.08);color-scheme:light}
html[data-theme=dark]{--bg:#0f141c;--card:#171e28;--soft:#202b38;--text:#edf2f7;--muted:#a8b3c2;--border:#334052;--blue:#62a6ff;--input:#111821;--shadow:0 8px 24px rgba(0,0,0,.22);color-scheme:dark}
*{box-sizing:border-box}body{margin:0;background:var(--bg);font-family:system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;color:var(--text)}.app{max-width:760px;margin:auto;min-height:100vh;padding-bottom:18px}.top{position:sticky;top:0;z-index:20;display:grid;grid-template-columns:1fr auto 1fr;align-items:center;gap:8px;padding:10px 12px;border-bottom:1px solid var(--border);background:color-mix(in srgb,var(--card) 96%,transparent)}.back{color:var(--blue);font-size:13px;font-weight:800;text-decoration:none}.brand{text-align:center;font-size:24px;font-weight:800}.brand .gas{color:var(--blue)}.controls{display:flex;justify-content:flex-end;gap:5px}.control,input{min-width:0;border:1px solid var(--border);border-radius:11px;background:var(--input);color:var(--text);font:inherit}.control{max-width:78px;padding:7px 5px;font-size:10px}main{padding:18px 14px 44px}.intro{margin:0 2px 16px}.intro h1{margin:0 0 6px;font-size:23px}.intro p{margin:0;color:var(--muted);font-size:13px;line-height:1.45}.card{margin-bottom:14px;padding:15px;border:1px solid var(--border);border-radius:18px;background:var(--card);box-shadow:var(--shadow)}.collapse-head{display:flex;align-items:center;justify-content:space-between;gap:12px;cursor:pointer;user-select:none}.collapse-head:focus-visible{outline:3px solid rgba(37,99,235,.25);outline-offset:5px;border-radius:8px}.section-title{font-size:16px;font-weight:700}.collapse-chevron{font-size:22px;line-height:1;transition:transform .15s ease}.collapse-head[aria-expanded=true] .collapse-chevron{transform:rotate(180deg)}.collapse-content{margin-top:14px;padding-top:14px;border-top:1px solid var(--border)}.hidden{display:none!important}.fields{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.fields-main{margin-bottom:12px}.fields label,.reference-box label{display:block;color:var(--muted);font-size:12px}.fields input,.reference-box input{width:100%;margin-top:5px;padding:11px}.reference-box{margin-top:14px;padding:12px;border-radius:14px;background:var(--soft)}.reference-box.two{display:grid;grid-template-columns:1fr 1fr;gap:10px}.small{margin:0 0 13px;color:var(--muted);font-size:12px;line-height:1.45}.collapse-content>.small:last-child{margin:12px 0 0}.invalid{border-color:#c2410c!important;box-shadow:0 0 0 2px rgba(194,65,12,.12)}
@media(max-width:560px){.top{grid-template-columns:auto 1fr auto}.brand{font-size:21px}.fields,.reference-box.two{grid-template-columns:1fr}.intro h1{font-size:21px}}

.signed-number{display:grid;grid-template-columns:minmax(0,1fr) 44px;gap:7px;align-items:end}.signed-number input{margin-top:5px}.sign-button{height:43px;margin-top:5px;border:1px solid var(--border);border-radius:11px;background:var(--soft);color:var(--blue);font:700 24px/1 system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;cursor:pointer;touch-action:manipulation}.sign-button:active{transform:translateY(1px)}.sign-button:focus-visible{outline:3px solid rgba(37,99,235,.25);outline-offset:2px}

.select-field{display:block;margin-bottom:12px;color:var(--muted);font-size:12px}.select-field select{width:100%;margin-top:5px;padding:11px;border:1px solid var(--border);border-radius:11px;background:var(--input);color:var(--text);font:inherit}.substance-data{display:grid;gap:10px;margin-bottom:12px;padding:12px;border-radius:14px;background:var(--soft)}.substance-data.two{grid-template-columns:1fr 1fr}.substance-data div{display:flex;flex-direction:column;gap:4px;color:var(--muted);font-size:12px}.substance-data strong{color:var(--text);font-size:14px;font-weight:700}
@media(max-width:560px){.substance-data.two{grid-template-columns:1fr 1fr}}

.conversion-table-wrap{overflow-x:auto;border:1px solid var(--border);border-radius:12px;-webkit-overflow-scrolling:touch}.conversion-table{width:100%;min-width:660px;border-collapse:collapse;background:var(--input);font-variant-numeric:tabular-nums}.conversion-table th,.conversion-table td{padding:9px 10px;border-right:1px solid var(--border);border-bottom:1px solid var(--border);text-align:center;white-space:nowrap}.conversion-table th:last-child,.conversion-table td:last-child{border-right:0}.conversion-table tbody tr:last-child td{border-bottom:0}.conversion-table th{background:#68707a;color:#fff;font-size:12px;line-height:1.3}.conversion-table td{color:var(--text);font-size:13px}.conversion-table-wrap+.small{margin-top:12px}