Toolbar refinements

[nckrtl]

Was taking another look at the toolbar and found some more things that could be improved

• Different paddings were being used for left and right side, this is now consistent
• Weird hover state on active tab/element
• Text appears bit fuzzy because of text shadow, I think its more clear to show it without a text shadow
• Icons on the right side seem to have different paddings, made those consistent as well
• applied better vertical alignment for the icons used on the right side

Visual side by side:

Also noticed that the rows of the request data is not nicely aligned anymore:

I saw this remark: https://github.com/barryvdh/laravel-debugbar/pull/1605#discussion_r1551759026 and also the PR that is causing the misalignment: https://github.com/barryvdh/laravel-debugbar/pull/1608

This CSS fixes the alignment, while making sure there is enough space for the key to be fully displayed and not being cut off.

dl.phpdebugbar-widgets-kvlist dt {
    width: 25%;
    width: calc(25% - 10px);
}

Note that this is now properly calculating the width instead of width: calc(25%-10px); which I included and then removed in some commits ago as it was invalid due to missing spaces.