Release the header stuck to the top

On a phone, you can try saving the code as a bookmark address. Copy the code below first.

iPhone (Safari): bookmark any page, touch and hold the bookmark, choose Edit, and replace its address with the copied code.

Android (Chrome): bookmark a page. Open Bookmarks, tap the three dots beside it, choose Edit, and replace its address with the copied code.

Then open the page you want to change and use the bookmark. If it does not run from the bookmarks menu, type the bookmark's name in the address bar and select its suggestion.

Copy bookmark code

Bookmark address javascript:void(function(){var list=document.querySelectorAll("header,[role='banner']");var i,el,cs,r;for(i=0;i<list.length;i++){el=list[i];cs=getComputedStyle(el);if(cs.position==="fixed"||cs.position==="sticky")el.style.setProperty("position","static","important");}list=document.body.getElementsByTagName("*");for(i=0;i<list.length;i++){el=list[i];cs=getComputedStyle(el);if(cs.position!=="fixed"&&cs.position!=="sticky")continue;r=el.getBoundingClientRect();if(r.top<48&&r.width>innerWidth*0.55&&r.height<innerHeight*0.45)el.style.setProperty("position","static","important");}}())

Support varies by browser and version. Some websites also block this kind of shortcut.

Another iPhone option: the Shortcuts app

In Shortcuts, create a shortcut with the Run JavaScript on Webpage action and paste the code below. Show it in the Share Sheet for Safari webpages. If prompted, allow running scripts in Shortcuts settings. Then open the page in Safari, tap Share, and choose your shortcut.

Copy code for Shortcuts

Code for the Shortcuts app void(function(){var list=document.querySelectorAll("header,[role='banner']");var i,el,cs,r;for(i=0;i<list.length;i++){el=list[i];cs=getComputedStyle(el);if(cs.position==="fixed"||cs.position==="sticky")el.style.setProperty("position","static","important");}list=document.body.getElementsByTagName("*");for(i=0;i<list.length;i++){el=list[i];cs=getComputedStyle(el);if(cs.position!=="fixed"&&cs.position!=="sticky")continue;r=el.getBoundingClientRect();if(r.top<48&&r.width>innerWidth*0.55&&r.height<innerHeight*0.45)el.style.setProperty("position","static","important");}}());completion();

Open the page you want to change. In Chrome, press Ctrl + Shift + J (Windows/Linux) or ⌘ + Option + J (Mac), paste the code below into the console, and press Enter.

Copy console code

Console code void(function(){var list=document.querySelectorAll("header,[role='banner']");var i,el,cs,r;for(i=0;i<list.length;i++){el=list[i];cs=getComputedStyle(el);if(cs.position==="fixed"||cs.position==="sticky")el.style.setProperty("position","static","important");}list=document.body.getElementsByTagName("*");for(i=0;i<list.length;i++){el=list[i];cs=getComputedStyle(el);if(cs.position!=="fixed"&&cs.position!=="sticky")continue;r=el.getBoundingClientRect();if(r.top<48&&r.width>innerWidth*0.55&&r.height<innerHeight*0.45)el.style.setProperty("position","static","important");}}())

The effect applies to the open page. Check what any code does before running it in the console; your browser may show a security warning.