Copy-paste the following into a file named "sidebar.js":
var html = '<div class="navlink"><a href="index.html">Home</a></div>';
var section1 = ['HTML', 'Java', 'CSS']//write one-word link names in this list
for (i = 0; i<section1.length; i++){
html += '<div class="navlink"><a href="' + section1[i] + '.html">' + section1[i] + '</a></div>'
}
html += '<div class="navlink"><a href="https://youtu.be/dQw4w9WgXcQ">Custom Link</a></div>'
document.getElementById("templaterr-topbar").innerHTML = html;
To add/remove/edit links, change the items in the list section1[].
Updates will apply to all pages.
The links must be one word, and capitalization counts, because Link1 will lead to Link1.html, but link1 will lead to link1.html. For multi-word links, external links, or links where the link text doesn't match the name of the page it links to, use this line instead:
html += '<div class="navlink"><a href="https://youtu.be/dQw4w9WgXcQ">LINKTEXT</a></div>'
and replace the youtube link with the link of your choice.
You can add images and anything else you want, too:
html += '<a href="https://templaterr.neocities.org/">
<img src="https://templaterr.neocities.org/templaterr1.png"></a>'