You have customized background of layout tour so you also need to customize text color to display better.
1. You go to edit layout tour and add extra class for “ST Tour Tab Content” row.
2. Next, You go to edit page of this tour and click to Page Setting and add your custom css. I have added sample code css in Page setting of this tour.
color: #000 !important;
You can see above code have “#000” string. This is color code. You can get color code in website:
Last, you need to save layout and tour.
You can see my attachments.