[Bug]: Subtitle sizing are applied to current size, not original size

[MagicalDrizzle]

Guidelines

• I have encountered this bug in the latest release of FreeTube.
• I have encountered this bug in the official downloads of FreeTube.
• I have searched the issue tracker for open and closed issues that are similar to the bug report I want to file, without success.
• I have searched the documentation for information that matches the description of the bug I want to file, without success.
• This issue contains only one bug.

Describe the bug

Choosing certain subtitle sizes will cause the percentage to apply to the current size of subtitle, not the original size of subtitle.
For example: Subtitle size is at 100% - Choosing 50% halves the subtitle size - Choosing 75% applies the 75% sizing to the halved subtitle size (gets smaller) . Applies to all sizes - For example choosing 200% then 400% will increase the size 2 * 4 = 8 times.
Also means that if you choose a size that's not 100% - it's impossible to get it back to 100%. (Because 75% * 100% = 75%)
Only applies if you choose a size that's not the size you already chose - i.e choosing 50% twice keep it at 50% normally.

Expected Behavior

Sizes should apply relative to original size, so choosing 50% then 75% would result in subtitles size being 75%.

Issue Labels

usability issue, visual bug

FreeTube Version

v0.21.3 Beta

Operating System Version

Windows 10 22H2

Installation Method

Portable

Primary API used

Local API

Last Known Working FreeTube Version (If Any)

No response

Additional Information

FreeTube_tkIjDtfqlZ.mp4

Nightly Build

• I have encountered this bug in the latest nightly build.