Legal Signing: Adhere to smaller signature widths + vertical alignment

[jakejackson1]

Description

Minor tweaks to the new Legal Signing field support added in https://github.com/GravityPDF/gravity-pdf/pull/1515

Checklist:

• [x] I've tested the code.
• [ ] My code is easy to read, follow, and understand
• [ ] My code follows the accessibility standards.
• [ ] My code has proper inline documentation / docblocks.

Additional Comments

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 76.16%. Comparing base (c7b7ba7) to head (f856150).

Files	Patch %	Lines
src/Helper/Fields/Field_Fg_Ls_Signature.php	0.00%	4 Missing :warning:
src/View/html/PDF/add_legalsigning_styles.php	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## development #1516 +/- ## =============================================== - Coverage 76.18% 76.16% -0.02% =============================================== Files 247 247 Lines 12870 12873 +3 Branches 370 370 =============================================== Hits 9805 9805 - Misses 3057 3060 +3 Partials 8 8 ```

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