incorrect icon: Improve close / checkmark icon.

[infacto]

Describe the Issue

Just a minor but somewhat annoying issue from a meticulous UI dev. Especially when using close and checkmark icon together. It seems that either the close is not correct or checkmark. You can decide.

Comparison

Type	Close	Checkmark	Compare	Comment
outline				Seems ok.
filled				The close appears too thick or the checkmark too thin.
sharp				Seems ok.

We see that the checkmark outline and filled appear the same. The filled checkmark should be thicker or the cross thinner.

[ionitron-bot[bot]]

This issue has been labeled as help wanted. This label is added to issues that we believe would be good for contributors.

If you'd like to work on this issue, please comment here letting us know that you would like to submit a pull request for it. This helps us to keep track of the pull request and make sure there isn't duplicated effort.

For a guide on how to create a pull request and test this project locally to see your changes, see our contributing documentation.

Thank you!