See T95628 for context.
Adding to collection modal is too space inefficient in portait phones making the experience painful.
As much as I like it the star at the top takes too much space on the phone screen :S There are things we could do to improve this modal:
[x] On phone screens halve the size of the star in the heading of the modal (https://gerrit.wikimedia.org/r/210088)
[x] On phone screens remove thumbnail (https://gerrit.wikimedia.org/r/210112)
- Halved instead of removed. Doesn't take space compared to the text.
[x] On phone screens halve the space between the title -- Add to new collection (32px) (https://gerrit.wikimedia.org/r/210112)
[x] Halve the space between the input+button and Add to existing collection (hr with 2em height). (https://gerrit.wikimedia.org/r/210112)
[ ] change text of input box to "name collection" (currently the suggested text gets cutoff)
Plz test throughly in several devices/screen sizes.