#sub_form {
    max-width: 325px;
    margin: 0 auto;
    padding: 0;
}

#sub_form .f-group {
    width: 98%;
    margin: 0.8em auto;
    padding: 0;
}

#sub_form .f-group input {
    width: 100%;
    border-radius: 0.1em;
    height: 1.3em;
    padding: 0.9em;
    border-radius: 0.4em;
}

#sub_form .f-group button {
    padding: 0.3em 0.6em;
    border: 1px solid gray;
    border-radius: 0.4em;
}