body {
    display: flex;
    align-items: center;
    padding-top: 40px;
    padding-bottom: 40px;
    background-color: #f5f5f5;
}

.math-logo {
    margin: 0 0 20px;
}
.math-logo img {
    width: 200px;
}

.form-signin {
    width: 100%;
    max-width: 330px;
    padding: 15px;
    margin: auto;
}

.form-signin .checkbox {
    font-weight: 400;
}

.form-signin .form-floating:focus-within {
    z-index: 2;
}

/* id & pw */
.form-signin input[type="password"] {
    margin: 4px 0 10px;
}