body { background: #f8f9fa; }
.certificate-img {
    display: block;
    margin: 30px auto;
    border: 2px solid #007bff;
    border-radius: 10px;
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
    max-width: 100%;
    height: auto;
}