Would be almost perfect, except for one glaring issues that had caused me to switch to a different theme. There is insufficient contrast between the active tab and other tabs. If you have many tabs open it is difficult to determine which is the active tab to close it. This causes enough friction in working in Firefox that it became a regular annoyance. For me it is a basic requirement that the active tab should be clearly indicated in the tab bar. This otherwise excellent theme fails in this regard.