Sitewide Demo Notice – move to top

I moved the demo sitewide notice to the top of the page, but it’s completely overlapping the fixed menu. How can I place it above the fixed menu?

my css

.demo_store {
    background-color: #ed4444;
    color: #fff;
    left: 0;
    margin: 0;
    padding: 1em 1.387em;
    position: fixed;
    right: 0;
    text-align: center;
    top: 0;
    z-index: 99999;