body {
    font-family: 'Source Sans Pro', sans-serif;
    background-color: #f0f0f0;
}

.container {
    max-width: 600px;
    margin: auto;
}

.card {
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

.card-header {
    background-color: #007bff;
    color: white;
    text-align: center;
    padding: 10px 0;
}

.card-body {
    padding: 20px;
}

.form-group {
    margin-bottom: 15px;
}

#canvas {
    display: none;
    border: 1px solid #ced4da;
    width: 100%;
}

.btn {
    width: 100%;
    margin-top: 10px;
}