Misc CSS fixes (#34638) (#34644)

Backport #34638 by @silverwind

1. apply [`text-wrap:
balance`](https://developer.mozilla.org/en-US/docs/Web/CSS/text-wrap#balance)
to various places making the text wrapping nicer, moving
`empty-placeholder` CSS to base because it's not repo-specific.

<img width="537" alt="Screenshot 2025-06-07 at 15 09 00"
src="https://github.com/user-attachments/assets/8b37d031-269d-4ab3-ba59-2ac469c431e4"
/>
<img width="514" alt="Screenshot 2025-06-07 at 15 11 16"
src="https://github.com/user-attachments/assets/27a63117-be1d-4797-80f7-9ed14cca41dc"
/>
<img width="346" alt="Screenshot 2025-06-07 at 15 22 26"
src="https://github.com/user-attachments/assets/2f371384-0330-4a00-bb79-bc3c50ba5c91"
/>

2. fix overflow-related bug on actions run list, before:

<img width="302" alt="Screenshot 2025-06-07 at 15 26 26"
src="https://github.com/user-attachments/assets/d6607eeb-288b-4e81-a770-45a421c9c68c"
/>

After:
<img width="299" alt="Screenshot 2025-06-07 at 15 26 59"
src="https://github.com/user-attachments/assets/b0ddb66f-d4fe-4711-8ed9-eca08ce608f3"
/>

Co-authored-by: silverwind <me@silverwind.io>

web_src/css/form.css

@@ -220,6 +220,7 @@ textarea:focus,
   color: var(--color-secondary-dark-5);
   padding-bottom: 0.6em;
   display: inline-block;
+  text-wrap: balance;
 }
 
 .m-captcha-style {