main {
    margin-left: auto;
    margin-right: auto;
    width: 600px;
    background: white;
    border-radius: 20px;
}

body {
    background-image: url("./bg.png");
    background-attachment: fixed;
}

.must {
    color: red;
}

input:invalid {
    border: 2px dashed red;
}

#basic-info, #pre-info, #pre-out, #get-thro, #button {
    width: 550px;
    margin-right: auto;
    margin-left: auto;
}

h1 {
    text-align: center;
}

h2 {
    width: 550px;
    background-color: gray;
    margin-left: auto;
    margin-right: auto;
    text-align: center;
}