body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    background-color: #e9ecef;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    overflow: hidden; 

}

@keyframes popIn {
    0% { transform: scale(0.6); opacity: 0; }
    70% { transform: scale(1.05); }
    100% { transform: scale(1); opacity: 1; }
}

.cert-container {
    text-align: center;
    background: white;
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    max-width: 600px;
    width: 90%;
    animation: popIn 0.6s cubic-bezier(0.175, 0.885, 0.32, 1.275) both;
}

.exercise-info h3 {
    color: #2c3e50;
    margin-bottom: 5px;
    animation: popIn 0.8s ease-out 0.2s both;
}

.cert-box {
    margin: 25px 0;
    border: 1px solid #ddd;
    padding: 10px;
    background: #fff;
    box-shadow: inset 0 0 5px rgba(0,0,0,0.05);
    animation: popIn 0.8s ease-out 0.4s both;
}

#certificate-img {
    display: block;
    width: 100%;
    height: auto;
}

.download-btn {
    display: inline-block;
    padding: 15px 30px;
    background-color: #28a745;
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: bold;
    transition: transform 0.2s, background 0.2s;
    animation: popIn 0.8s ease-out 0.6s both;
}

.download-btn:hover {
    background-color: #218838;
    transform: translateY(-2px);
}