#error {
    color: red;
}

form {
    padding: 1em;
    display: flex;
    flex-direction: column;
    gap: 1em;
    width: 13em;
    margin: auto;
    font-size: 1.5em;
    font-family: sans-serif;
    color: #222;
}

input {
    font-size: 1em;
    width: 100%;
}

input[type="submit"] {
    background: #ff3e00;
    color: white;
    text-transform: uppercase;
    border: none;
    border-radius: 5px;
    padding: 0.3em;
    box-shadow: 0 0 5px #0008;
}

input[type="text"] {
    border: none;
    border-bottom: 1px solid gray;
    margin-bottom: 1px;
}

input[type="text"]:focus {
    outline: none;
    margin-bottom: 0;
    border-bottom: 2px solid black;
}

@media (prefers-color-scheme: dark) {

    body,
    input,
    form {
        background: #000;
        color: #fff9;
    }

    input[type="text"]:focus {
        border-bottom: 2px solid white;
    }
}