Improve UI spacing on bigger text sizes

I think allowing users to set the text size instead of providing fractional scaling is a very good idea to begin with but the spacing between UI elements needs some improvement. For example, on Code (screenshot below) with 1x scaling factor and the font size set to 1.5 everything feels too compact and not really breathable and evenly spaced.


I think a good rule of thumb to get the spacing right would be using `xrandr` with the 2x scaling factor to zoom out the screen (screenshot below) so that the zoomed out font size on 2x matches the preferred font size on 1x.


As you can see, the scaled down version looks more pleasant spacing-wise, the titlebar is bigger, the tabs view is bigger, the drop-shadow is heavier and there is much more spacing between the menu entry and it's corresponding keyboard shortcut. The wingpanel is also more comfortably-spaced as opposed to the first version where the applications menu is so near my monitor bezel I can't stand it.

以 1x 缩放和 1.5 的字体大小重现 UI，然后将其与使用 xrandr 在 2x 缩放下生成的屏幕截图进行比较。检查标题栏、选项卡、菜单间距、键盘快捷键、投影阴影和 wingpanel；当较大文本的布局也具有同样舒适且均匀的间距时，工作就完成了。

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