Hi Ken,
From your description, it sounds like the blue border lines are part of the post item styling used in the Category archive layout provided by the theme, not a specific Category setting.
At the moment, there is no separate option in the Category settings to control post borders individually. These borders are defined via CSS.
All custom style adjustments in WordPress can be added globally via:
Appearance → Customize → Additional CSS
For example, if the border comes from the post card component, it can typically be hidden with a CSS rule similar to:
.query-post__wrap .query-post__thumbnail a::after {
border-color: rgba(0, 51, 255, 0.2);
}
.query-post__wrap .query-post__content::before {
background-color: rgba(0, 51, 255, 0.2);
}
.query-post__wrap .query-post__content::after {
background-color: rgba(0, 51, 255, 0.2);
}
I do not know the exact color value used on your site, so I used a random blue color as an example. If you want to completely hide these lines, you can simply replace the color value with transparent.
Best regards,
TigriWeb Team