body{background-color:#f8f9fa;font-family:"Segoe UI",Roboto,Arial,sans-serif}header h1{font-size:2.5rem;font-weight:700}header h2{font-size:1.2rem;color:#6c757d}.calculator-card{background:#fff;border-radius:1rem;box-shadow:0 4px 10px rgba(0,0,0,.05)}.result-box{font-size:1.5rem;font-weight:700;color:#212529}footer{font-size:.9rem;color:#6c757d;margin-top:2rem}.ad-placeholder{background:#e9ecef;border:2px dashed #adb5bd;display:flex;align-items:center;justify-content:center;color:#6c757d}