:root{
  --green:#28a745;
  --muted:#20124d;
  --bg:#fff;
  --border:#000;
}
.bmi-widget{max-width:600px;margin:0 auto;background:var(--bg);padding:20px;border-radius:12px;box-shadow:0 4px 15px rgba(0,0,0,0.1);}
.unit-tabs{display:flex;gap:8px;margin-bottom:15px;}
.unit-tabs button{padding:8px 12px;border:1px solid #ddd;border-radius:8px;background:#7393B3;cursor:pointer;}
.unit-tabs button.active{background:var(--green);color:#fff;border-color:var(--green);}
.grid{display:grid;grid-template-columns:1fr 1fr;gap:12px;}
label{font-size:14px;color:var(--muted);margin-bottom:4px;display:block}
input, select{padding:8px;border:1px solid #ccc;border-radius:8px;width:100%;font-size:14px}
.btn{padding:10px 16px;background:var(--green);color:#fff;border:none;border-radius:10px;cursor:pointer;font-weight:600;margin-top:12px}
.btn.reset{background:#fff;color:var(--green);border:1px solid var(--green);margin-left:10px}
.result-box{margin-top:20px;padding:20px;text-align:center;border:4px solid var(--border);border-radius:12px;transition:background 0.5s,color 0.5s;}
.bmi-value{font-size:28px;font-weight:700;}
.bmi-label{font-size:16px;color:var(--muted);}