The theme has elements with colors that look good only on a white background. On a colored background, these colors look out of place.I Suggest that you do not use opaque colors in the theme.

For example, the theme has an indication for coloring a table through a row.

table tbody > tr:nth-child(odd) > th {background-color: #eeeeee; }
table tbody tr:hover > th {background-color: #e9e9e9; }
table tbody + tbody {border-top: 2px solid #cccccc; }

I believe that this unnecessary element should only be present in the form of a translucent color, for example, replace the #eeeeee color with #bbbbbb40. This approach is more universal, for cases if it is necessary to specify the color.

The values of colors and transparency should be selected to look acceptable on any background color.