:root{--ink:#1f2328;--muted:#5b6470;--line:#d8dde3;--bg:#f5f6f8;--card:#fff;--brand:#b45309;--brand-ink:#7c3a06;--accent:#0f766e}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;font:16px/1.55 system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif;color:var(--ink);background:var(--bg)}
.wrap{max-width:960px;margin:0 auto;padding:0 16px}
.hidden{display:none!important}
.site-header{background:var(--card);border-bottom:1px solid var(--line)}
.site-header .wrap{display:flex;align-items:center;justify-content:space-between;height:60px}
.brand{font-weight:800;font-size:1.35rem;text-decoration:none;color:var(--ink);letter-spacing:-.01em}
.brand span{color:var(--brand)}
.site-header nav a{margin-left:18px;color:var(--muted);text-decoration:none;font-size:.95rem}
.site-header nav a:hover{color:var(--ink)}
h1{font-size:2rem;margin:28px 0 6px;letter-spacing:-.02em}
.lede{color:var(--muted);margin:0 0 20px;max-width:70ch}
.calc{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:18px;box-shadow:0 1px 2px rgba(0,0,0,.04)}
.tabs{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:14px}
.tab{border:1px solid var(--line);background:#fafbfc;color:var(--ink);padding:8px 14px;border-radius:999px;cursor:pointer;font:inherit;font-size:.92rem}
.tab.active{background:var(--brand);border-color:var(--brand);color:#fff;font-weight:600}
fieldset{border:0;padding:0;margin:0 0 14px}
legend{font-weight:600;margin-bottom:8px;padding:0}
.row{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:12px}
label{display:flex;flex-direction:column;font-size:.9rem;color:var(--muted);gap:4px}
label small{font-size:.78rem}
.dim{display:flex}
.dim input{flex:1;min-width:0;border-radius:8px 0 0 8px}
.dim select,.dim .unit{border:1px solid var(--line);border-left:0;background:#f0f2f5;border-radius:0 8px 8px 0;padding:0 10px;font:inherit;color:var(--ink);display:flex;align-items:center}
.dim .unit:first-child{border-left:1px solid var(--line);border-right:0;border-radius:8px 0 0 8px}
.dim .unit:first-child+input{border-radius:0}
input[type=number]{width:100%;padding:10px 12px;border:1px solid var(--line);border-radius:8px;font:inherit;font-size:1rem;color:var(--ink);background:#fff}
input[type=number]:focus,select:focus{outline:2px solid var(--accent);outline-offset:1px}
.options{border-top:1px solid var(--line);padding-top:14px}
.results{margin-top:18px;background:#fbf7f2;border:1px solid #f0e2d1;border-radius:10px;padding:16px}
.primary{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:12px}
.stat{background:#fff;border-radius:8px;padding:12px;text-align:center;border:1px solid #f0e2d1}
.stat .num{display:block;font-size:1.9rem;font-weight:800;color:var(--brand-ink);letter-spacing:-.02em}
.stat .lbl{display:block;color:var(--muted);font-size:.85rem}
.note,.readymix{margin:12px 0 0;color:var(--muted)}
.readymix{color:var(--accent);font-weight:600}
.results h3{margin:18px 0 8px;font-size:1.05rem}
.results h3 small{font-weight:400;color:var(--muted);font-size:.85rem}
table.bags{width:100%;border-collapse:collapse;background:#fff;border-radius:8px;overflow:hidden;font-size:.95rem}
table.bags th,table.bags td{padding:8px 10px;text-align:left;border-bottom:1px solid var(--line)}
table.bags th{background:#f0f2f5;font-weight:600;color:var(--muted);font-size:.85rem}
table.bags tr:last-child td{border-bottom:0}
table.bags td:nth-child(n+3),table.bags th:nth-child(n+3){text-align:right}
.cost{margin:12px 0 0;font-weight:600}
.ad-slot{min-height:90px;margin:24px 0;border:1px dashed var(--line);border-radius:8px}
.content{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:18px 20px;margin:20px 0}
.content h2{margin-top:0;font-size:1.4rem}
.content h3{font-size:1.05rem;margin:18px 0 6px}
.content p,.content li{color:#333;max-width:75ch}
.site-footer{margin-top:30px;padding:20px 0;border-top:1px solid var(--line);color:var(--muted);font-size:.85rem;text-align:center}
@media (max-width:600px){h1{font-size:1.6rem}.site-header nav{display:none}.stat .num{font-size:1.5rem}}