This PR should be enhanced, since the width and the box-sizing rule is applied only to textarea template variables. Other rules seems to be missing (input etc.).

@Jako Care to elaborate how you tested this? I can take it for a spin and check if some of the other classes needs to be adjusted too.

I just have read the scss code. There is no width adjustment for a text TV. Only a textarea TV has a width: 100%!important;, which should do the job.

I'll try to test this properly. I am still a bit unsure how this works.

This habit of yours to submit PRs that other people made, without knowing how to test it, is interesting @OptimusCrime ;)

This does not fix the problem reported in #13323. The built CSS resolves to this:

  .x-form-item #modx-resource-main-columns .modx-tv textarea {
    box-sizing: border-box;
    width: 100% !important;
    min-width: 200px; }
  .x-form-item #modx-resource-main-columns .modx-tv input[type="text"] {
    line-height: 20px;
    height: auto; }
  .x-form-item #modx-resource-main-columns .modx-tv .x-superboxselect-input-field {
    min-width: 200px; }

while the #modx-resource-main-columns should be at the front of the definition.

Would you like to correct this @OptimusCrime or should the PR be closed?