Bulgarian grey โดย Bobi Bulgaria

A solid gray theme that offers easier readability thanks to the light grey background and highly contrasting black fonts. Optimized for tabs on bottom and visible Menu bar.

For tabs on bottom in Firefox 57+, follow the instructions here: https://tinyurl.com/ybnfbuv8

For tabs on bottom in Firefox 65, replace the chrome.css with this one: https://tinyurl.com/yd9hb474

For custom tab bar color, add this text to the chrome.css: #tabbrowser-tabs {
--tab-line-color: #B200FF !important;
}