body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f4f4f4;
    margin: 0;
}
.container {
    background-color: #fff;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
    max-width: 400px;
    width: 90%;
}
h1 {
    margin-bottom: 20px;
    font-size: 1.5em;
    text-align: center;
    color: #333;
}
label {
    margin-top: 10px;
    font-weight: bold;
    color: #555;
}
input, select {
    width: 100%;
    padding: 10px;
    margin-top: 5px;
    margin-bottom: 15px;
    border: 1px solid #ddd;
    border-radius: 5px;
}
button {
    width: 100%;
    padding: 10px;
    background-color: #4CAF50;
    color: #fff;
    border: none;
    border-radius: 5px;
    font-size: 1em;
    cursor: pointer;
}
button:disabled {
    background-color: #cccccc;
    cursor: not-allowed;
}
.hidden {
    display: none;
}
#popup {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    display: flex;
    justify-content: center;
    align-items: center;
}
.popup-content {
    background: white;
    padding: 20px;
    border-radius: 10px;
    text-align: center;
    max-width: 300px;
    width: 80%;
    box-shadow: 0px 4px 10px rgba(0, 0, 0, 0.3);
}
.popup-content p {
    font-size: 1.2em;
    color: #333;
}
.close-btn {
    position: absolute;
    top: 10px;
    right: 10px;
    cursor: pointer;
    font-size: 1.5em;
    color: #333;
}