React_homework/src/Header.css

header {
    font-family: "Helvetica Neue";
    text-align: center;
    margin-bottom: 30px;
    min-width: 1200px;
}

.menu {
    background-color: rgb(44, 43, 43);
    height: 50px;
    text-align: center;
}

.menu-list {
    width: 400px;
    color: white;
    list-style-type:none;
    padding-top: 15px;
    display: flex;
    justify-content: space-between;
    margin-left: auto;
    margin-right: auto;
}

a {
    text-decoration: none;
    color: white;
}

@media (max-width:1200px) {
    header {
        max-width: 970px;
    }
}

@media (max-width:992px) {
    header {
        max-width: 750px;
    }
}

@media (max-width:767px) {
    header {
        max-width: none;
    }
}