body {
    position: relative;
}

section {
    width: 300px;
    height: 300px;
    margin: 0 auto;
    background-color: #f5f5f5;
    text-align: center;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, 50%);
}

label, input, button {
    margin-top: 100px;
}

button {
    cursor: pointer;
}
.checkMsg {
    margin-top: 50px;
}