Cookie banner

<div class="banner">
<!-- Tells visitors that the website uses cookie -->
<div class="banner__content">
...
</div>
<!-- Close button -->
...
</div>
.banner {
/* Banner is displayed at the bottom */
bottom: 0;
left: 0;
position: fixed;
width: 100%;
/* Center the content */
align-items: center;
display: flex;
justify-content: center;
}
.banner__content {
/* Take available width */
flex: 1;
}

See also

Fixed at corner