header {
    margin-top: 40px;
}
header h1 {
    text-align: center;
}
header form {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin: 30px 100px 0 100px;
    /* margin-top: 10px; */
}
header input {
    padding: 12px 18px;
}
header input:invalid, header textarea:invalid{
    border: solid rgba(255, 0, 0, 0.8) 1px;
    outline: solid rgba(255, 0, 0, 0.4) 2px;
}
header input:valid, header textarea:valid{
    border: solid green 1px;
    outline: solid rgba(0, 128, 0, 0.5) 2px;
}
header input, header textarea {
    padding: 12px 18px;
    width: 100%;
}
header form button {
    border-radius: 3px;
    margin-top: 20px;
}
/* :has(condition) */
header form:has(:invalid) button {
    opacity: 0.5;
    cursor: not-allowed;
}
header form:has(:invalid) button:hover {
    background-color: var(--purple);
    border: 1px solid transparent;
    color: white;
}
header textarea {
    min-width: 100%;
    max-width: 100%;
    min-height: 100px;
    max-height: 240px;
}


@media (max-width: 1000px) {
    header form {
        width: 80%;
        margin: 40px auto;
    }
}