header {
    background: #232526;
    color: #bbfcfb;
    padding: 12px 0;
    position: fixed;
    width: 100%;
    top: 0;
    left: 0;
    z-index: 100;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}

header ul {
    display: flex;
    justify-content: center;
    gap: 30px;
    list-style: none;
}

header a {
    color: #bbfcfb;
    text-decoration: none;
    font-weight: bold;
    font-size: 17px;
    transition: color 0.2s;
}

header a:hover {
    color: #fff;
}