:root{--ink:#1d2433;--muted:#5b6474;--line:#e3e7ee;--bg:#f6f8fb;--brand:#1769e0;--brand2:#0f4fb0;--ok:#127a4a;--card:#fff}
*{box-sizing:border-box}
body{margin:0;font:16px/1.6 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;color:var(--ink);background:var(--bg)}
a{color:var(--brand2)}
.wrap{max-width:980px;margin:0 auto;padding:0 20px}
header.site{background:#fff;border-bottom:1px solid var(--line)}
header.site .wrap{display:flex;align-items:center;justify-content:space-between;min-height:60px;flex-wrap:wrap;gap:8px}
.logo{font-weight:800;font-size:20px;letter-spacing:-.3px;color:var(--ink);text-decoration:none}.logo span{color:var(--brand)}
nav.main a{color:var(--muted);text-decoration:none;margin-left:22px;font-size:15px}
nav.main a:hover,nav.main a[aria-current]{color:var(--ink)}
.hero{text-align:center;padding:48px 0 18px}
.hero h1{font-size:40px;line-height:1.15;margin:0 0 10px;letter-spacing:-.8px}
.hero p{color:var(--muted);font-size:18px;margin:0 auto;max-width:620px}
.card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:24px;box-shadow:0 1px 2px rgba(20,30,50,.04)}
.lookup,.result,.remind,.section{margin:22px auto 0;max-width:760px}
.section h2{font-size:24px;margin:0 0 12px}
.lookup label.big{display:block;font-weight:700;margin-bottom:10px}
.dims{display:flex;align-items:flex-end;gap:10px;flex-wrap:wrap}
.dims .f{display:flex;flex-direction:column}
.dims .f span{font-size:12px;color:var(--muted);margin-bottom:4px;text-transform:uppercase;letter-spacing:.5px}
.dims input{width:110px;font-size:22px;padding:10px 12px;border:1.5px solid var(--line);border-radius:10px;text-align:center}
.dims input:focus{outline:none;border-color:var(--brand)}
.x{font-size:22px;color:var(--muted);padding-bottom:10px}
button,.btn{cursor:pointer;border:0;border-radius:10px;font-weight:700;font-size:16px;padding:13px 20px;background:var(--brand);color:#fff;text-decoration:none;display:inline-block}
button:hover,.btn:hover{background:var(--brand2)}
.chips{margin-top:16px;display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.chips small{color:var(--muted);margin-right:4px}
.chip{background:#eef3fc;color:var(--brand2);border:1px solid #d6e2f8;border-radius:999px;padding:6px 14px;font-weight:600;font-size:14px}
.chip:hover{background:#dfe9fb}
.hint,.note{font-size:14px;color:var(--muted);margin-top:14px}
.result h2{margin:0 0 4px;font-size:24px}
.result h3{font-size:17px;margin:20px 0 10px}
.tag{display:inline-block;font-size:12px;font-weight:700;color:var(--ok);background:#e6f5ee;border-radius:6px;padding:2px 8px;margin-left:8px;vertical-align:middle}
.sizes{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:16px 0}
.box{border:1px solid var(--line);border-radius:10px;padding:14px;background:#fafbfd}
.box b{display:block;font-size:20px}.box small{color:var(--muted)}
.merv{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}
.opt{border:1.5px solid var(--line);border-radius:12px;padding:16px;display:flex;flex-direction:column}
.opt h4{margin:0 0 6px;font-size:18px}
.opt p{margin:0 0 14px;color:var(--muted);font-size:14px;flex:1}
.opt .btn{font-size:14px;padding:10px 12px;text-align:center}
.aff{font-size:11px;color:var(--muted);text-align:center;margin-top:6px}
.disclose{font-size:13px;color:var(--muted);background:#fff8e6;border:1px solid #f3e2b3;border-radius:8px;padding:8px 12px;margin-top:14px}
.remind{display:flex;gap:20px;align-items:center;background:#10213f;color:#fff;border:0;flex-wrap:wrap}
.remind h3{margin:0 0 4px;color:#fff}.remind p{margin:0;color:#c5d1e6;font-size:14px}
.remind form{display:flex;gap:8px;flex-wrap:wrap}
.remind input,.remind select{padding:12px;border-radius:10px;border:0;font-size:15px}
.remind input{width:220px}
.thanks{display:none;color:#9be3bf;font-weight:600}
.guides-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.guides-grid a{display:block;background:#fff;border:1px solid var(--line);border-radius:12px;padding:16px;text-decoration:none;color:var(--ink)}
.guides-grid a:hover{border-color:var(--brand)}
.guides-grid b{display:block;margin-bottom:4px}.guides-grid span{color:var(--muted);font-size:14px}
details{background:#fff;border:1px solid var(--line);border-radius:10px;padding:14px 18px;margin-bottom:10px}
summary{font-weight:700;cursor:pointer}details p{color:var(--muted);margin:10px 0 0}
article{background:#fff;border:1px solid var(--line);border-radius:14px;padding:32px 40px;margin:14px auto 0;max-width:760px}
article h1{font-size:32px;line-height:1.2;margin:0 0 8px;letter-spacing:-.5px}
article .lede{color:var(--muted);font-size:18px;margin-top:0}
article h2{font-size:21px;margin:28px 0 8px}
article li{margin-bottom:6px}
.crumbs{font-size:13px;color:var(--muted);max-width:760px;margin:22px auto 0}
.crumbs a{color:var(--muted)}
.cta{background:#eef3fc;border:1px solid #d6e2f8;border-radius:12px;padding:16px 18px;margin-top:28px}
table{width:100%;border-collapse:collapse;margin:14px 0;font-size:15px}
th,td{text-align:left;padding:9px 10px;border-bottom:1px solid var(--line)}
th{background:#fafbfd;font-size:13px;text-transform:uppercase;letter-spacing:.4px;color:var(--muted)}
footer.site{color:var(--muted);font-size:13px;text-align:center;padding:30px 0 36px;margin-top:40px;border-top:1px solid var(--line);background:#fff}
footer.site nav a{color:var(--muted);margin:0 10px}
footer.site p{margin:10px 0 0}
@media (max-width:700px){.merv,.guides-grid,.sizes{grid-template-columns:1fr}article{padding:22px}.hero h1{font-size:30px}nav.main a{margin-left:14px}}