fix: make slider 100% height and hide thumb in firefox

[Jondyr]

Description

Add some missing css to make component width setting display correctly on firefox.

Before:

After:

Related Issue(s)

• Grid width in Firefox #13485

Verification

• Your code builds clean without any errors or warnings
• Manual testing done (required)
• Relevant automated test added (if you find this hard, leave it and we'll help out)

Documentation

• User documentation is updated with a separate linked PR in altinn-studio-docs. (if applicable)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.56%. Comparing base (cc8754c) to head (53f4475).
Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #14305   +/-   ##
=======================================
  Coverage   95.56%   95.56%           
=======================================
  Files        1843     1843           
  Lines       23886    23886           
  Branches     2752     2752           
=======================================
  Hits        22827    22827           
  Misses        802      802           
  Partials      257      257           

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[lassopicasso]

Well done, now should 🔥🦊 be happy!

[JamalAlabdullah]

tesed ok in dev 👍