index.css

*,
*::before,
*::after {
    box-sizing: 0;
    margin: 0;
    padding: 0;
}

body {
    background-image: linear-gradient(90deg, #64b3f4, #c2e59c);
    font-family: 'Cascadia code';
    font-size: 1rem;
    color: #444;
}

.container {
    text-align: center;
    padding-top: 5rem;
}

.formulaire {
    display: flex;
    align-items: center;
    flex-direction: column;
}

input {
    font-family: 'Cascadia code';
    font-size: 1rem;
    font-style: italic;
    padding: 1rem;
    margin: 0.2rem;
}

[type="email"]:active,
[type="email"]:focus,
[type="password"]:active,
[type="password"]:focus {
    outline: 0;
    border: 2px solid #007bff;
}

[type="email"],
[type="password"],
[type="submit"] {
    display: inline-block;
    -webkit-appearance: none;
    padding: .5rem 1rem;
    font-size: 1rem;
    border: 2px solid #ccc;
    border-radius: 4px;
}

[type="submit"] {
    cursor: pointer;
    background: #007bff;
    color: white;
    border: 2px solid #007bff;
    margin: 0.5rem;
    font-family: 'Cascadia code';
}

span {
    color: red;
    font-style: italic;
    font-size: 0.8rem;
    text-align: left;
}

div {
    text-align: center;
}

a {
    text-decoration: underline;
    font-style: italic;
    text-align: center;
    color: black
}