For HTML Users/Customizers
For activating sticky header first you need to find the .site-header
markup
Then Place the .sticky-header class after the .site-header--sticky
<div class="site-header">
...
<div>
<div class="site-header site-header--sticky">
...
<div>
By default it will be sticky on desktop only. For enabling sticky header on mobile also you have to add .mobile-sticky-enable class along with the .site-header--sticky