header {
    background-color: var(--background-color);
    color: black;
    width: 100%;
    text-decoration: none;
    position: fixed;
    top: 0;
    left: 0;
    padding: 10px 20px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
    z-index: 1000;
    font-family: var(--font-family);
}

header li {
    display: inline-block;
    margin: 0 15px;
}

header img {
    height: 2em;
    vertical-align: middle;
}

header a, 
header li button {
    color: black;
    text-decoration: none;
    transition: color 0.3s;
    border: none;
    background-color: transparent;
    font-size: 1em;
}

header a:hover,
header li button:hover {
    color: var(--input-button-color);
}