It's just a suggestion, but it might improve the look of checked items to also strike icons:
.remarkup-checked-item .phui-font-fa::after { content: ''; background-color: #92969D; height: 1px; display: block; position: relative; top: -6px; }
This is a little hacky but it works!
Also, shouldn't icons be grey too?
.remarkup-checked-item .phui-font-fa { color: #92969D; }
Example:
- Cameras
- Folders
- Peoples