selectionBackground and selectionHighlightBackground are the same color

[notpushkin]

Hello and first of all thanks for such a beautiful theme!

I have tried out the bright version today and noticed that colors for editor.selectionBackground and editor.selectionHighlightBackground are the same. This have often confused me (i. e. I've copied the whole line a few times, thinking a word/string I needed is selected while in fact it was not). I have overridden the highlight color in my settings.json:

"workbench.colorCustomizations": {
  "editor.selectionHighlightBackground": "#F9CEC34D"
}

However I think this might be good to fix in the theme itself. I can work on a PR sometime this week if you want :)