.erreur {
    text-align: center;
    width: 100%;
    padding: 30px;
    font-size: 30px;
    background-color: red;
    color: white;
}
.titre {
    text-align: center;
    text-decoration: underline;
    margin-bottom: 50px;
    font-size: 70px;
}
label, input {
    font-size: 20px;
}
.inputs_login {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}
label + input {
    margin: 10px 0;
}
.input_username, .input_password {
    width: 300px;
    height: 35px;
}
.checkbox {
    display: flex;
    justify-content: center;
    align-items: center;
    margin-top: 30px;
}

.btn_submit {
    display: flex;
    justify-content: center;
    align-items: center;
    margin:  30px auto;
    padding: 20px 30px;
    border-radius: 10px;
    background-color: #c9f9ff;
    font-size: 30px;
}
.btn_submit:hover {
    transition: 0.2s ease-in-out;
    background: #90d7ff;
    box-shadow: 10px 10px 20px lightblue;
}