.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

h1 {
    color: #2c3e50;
    text-align: center;
    margin-bottom: 30px;
    font-size: 2.5em;
    margin-top: 20px;
}

.upload-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 40px;
}

.drop-zone {
    border: 3px dashed #3498db;
    border-radius: 20px;
    width: 80%;
    max-width: 600px;
    margin: 20px 0;
    padding: 40px 20px;
    text-align: center;
    transition: all 0.3s ease;
    background-color: #ecf0f1;
}

.drop-zone:hover,
.drop-zone.dragover {
    background-color: #d6eaf8;
    border-color: #2980b9;
}

.drop-zone p {
    font-size: 1.2em;
    color: #7f8c8d;
    margin: 0;
}

.btn {
    display: block;
    width: 80%;
    max-width: 400px;
    padding: 15px;
    background-color: #3498db;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1.1em;
    cursor: pointer;
    transition: background-color 0.3s ease;
    margin-top: 20px;
}

.btn:hover {
    background-color: #2980b9;
}

#message {
    width: 80%;
    max-width: 400px;
    margin-top: 20px;
    padding: 15px;
    border-radius: 8px;
    text-align: center;
    font-weight: bold;
}

.success {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.error {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.info-box {
    background-color: #ffffff;
    border-radius: 8px;
    padding: 20px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.info-box h2 {
    color: #3498db;
    margin-top: 0;
}

.info-box ol,
.info-box ul {
    padding-left: 20px;
}

@media (max-width: 600px) {
    .container {
        padding: 10px;
    }

    h1 {
        font-size: 2em;
    }

    .drop-zone {
        width: 90%;
        padding: 20px;
    }

    .btn {
        width: 90%;
    }

    #message {
        width: 90%;
    }

    .message-box {
        width: 80%;
        max-width: 400px;
        margin-top: 20px;
        padding: 15px;
        border-radius: 8px;
        text-align: center;
        font-weight: bold;
        font-size: 1.1em;
    }

    .message-box.success {
        background-color: #d4edda;
        color: #155724;
        border: 1px solid #c3e6cb;
    }

    .message-box.error {
        background-color: #f8d7da;
        color: #721c24;
        border: 1px solid #f5c6cb;
    }
}

.btnda {
    display: block;
    margin: 20px auto; /* Centers the button horizontally */
    padding: 10px 20px;
    background-color: #3498db; /* Subtle blue background */
    color: white; /* White text */
    border: none;
    border-radius: 5px;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1); /* Light shadow for depth */
}

.btnda:hover {
    background-color: #2980b9; /* Slightly darker blue on hover */
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2); /* Increase shadow on hover */
}

.btnda:disabled {
    background-color: #bdc3c7; /* Gray background for disabled state */
    cursor: not-allowed;
    box-shadow: none;
}

.btnda:focus {
    outline: none;
    box-shadow: 0 0 0 4px rgba(52, 152, 219, 0.4); /* Focus ring for accessibility */
}