header {
    background: #fff;
    position: sticky;
    top: 0;
    left: 0;
    right: 0;
}

header nav a {
    text-decoration: none;
    margin-left: 48px;
    font-size: 18px;
    transition: background 300ms ease, color 300ms ease;
}

header nav a:hover {
    color: #2196f3;
}

.content-header {
    max-width: 1200px;
    margin: 0 auto;
    height: 80px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.content-header .content-header-sign-up {
    border: 1px solid #2196f3;
    padding: 4px 16px;
    border-radius: 20px;
}

.content-header .content-header-sign-up:hover {
    background: #bababa;
    color: #fff;
}