:root{--accent:#0d6efd;--muted:#6c757d;--card-bg:#ffffff}body,html{height:100%}body{background:linear-gradient(180deg,#f8fafc 0,#eef2f6 100%);color:#0b1a2b;font-family:Inter,system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial;padding-bottom:2rem}header{padding:1.25rem 0;text-align:center}header h1{font-weight:700}header h2{font-weight:500;color:var(--muted);font-size:1rem}.card{border-radius:.75rem;background:var(--card-bg);box-shadow:0 6px 24px rgba(2,6,23,.06)}.ad-placeholder{background:linear-gradient(180deg,#fff,#f4f6f8);border:1px dashed rgba(0,0,0,.06);border-radius:.6rem;height:90px;display:flex;align-items:center;justify-content:center;color:var(--muted)}.ad-300{height:250px}.result-value{font-size:1.3rem;font-weight:700;color:var(--accent)}.small-muted{color:var(--muted)}.mono{font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,"Roboto Mono",monospace}.btn-flat{background:0 0;border:1px solid rgba(0,0,0,.06)}