body{font-family:'Segoe UI',Tahoma,sans-serif;background:#f9f9f9;color:#222}header{background:#0d6efd;color:#fff;padding:2rem 1rem;text-align:center}h1{font-size:2.2rem;margin-bottom:.5rem}h2{font-size:1.2rem;font-weight:300}main{padding:2rem 1rem}.calculator-card{background:#fff;border-radius:1rem;box-shadow:0 2px 6px rgba(0,0,0,.1);padding:2rem}#result{font-size:1.5rem;font-weight:700;margin-top:1rem}footer{background:#222;color:#ccc;text-align:center;padding:1.5rem 1rem;margin-top:2rem}.ad-box{background:#e9ecef;border:1px dashed #aaa;display:flex;align-items:center;justify-content:center;color:#666;font-size:.9rem}