* {
    box-sizing: border-box;
}
html {
    height: 100%;
}
body {
    margin: 0;
    padding: 0;
    background: #F0F0F0;
    background-size: cover;
    width: 100%;
    height: 100%;
    color: #111111;
}
main {
    width: min(840px, 100%);
    margin: 80px auto 20px auto;
    border-radius: 20px;
}
.form_item label {
    display: block;
}
input {
    margin: 0.4rem;
}
#user_name, #email {
    display: block;
    width: 100%;
}
#user_name input, #email input {
    width: 90%;
}
textarea {
    display: block;
    width: 100%;
    height: 12rem;
}