Slider and Range Slider styling updates

[jasonpnp]

Slider

Range slider

Updated styling for the Slider and Range Slider components:

• Made the both inputs (min + max) to have dynamic sizing based on the number of digits in the slider range
• Min and max inputs will have the same size (aligned to the max size/range)
• Centered the slider rail relative to the inputs when no tick marks are displayed

First PR in this repo so apologies if I'm going off script on how these should structured 😞

Contributor Checklist

• I have broken down my PR scope into the following TODO tasks
  • Make slider and range slider input sizes dynamic
  • Visually center the slider rail relative to the inputs when the tick marks are not shown
• I have run the tests locally and they passed. (refer to testing section in contributing)
• I have added tests, or extended existing tests, to cover any new features or bugs fixed in this PR

optionals

• I have added entry in the CHANGELOG.md
• If this PR needs a follow-up in dash docs, community thread, I have mentioned the relevant URLS as follows
  • this GitHub #PR number updates the dash docs
  • here is the show and tell thread in Plotly Dash community

[ndrezn]

YES @jasonpnp ! Thank you for contributing to Dash!

[T4rk1n]

Need to target the v4 branch.

[KoolADE85]

@jasonpnp is there a particular reason you added fallback values to various CSS rules?
dcc.css defines these CSS variables, so they are meant to always be available.
And if the fallback values were to ever apply, that means a significant bug is being glossed over that would affect custom themes and DDK.
So I'd rather just remove the fallback so we see obvious visual bugs, should they ever occur.

[jasonpnp]

@KoolADE85 I added fallback values because I was getting build errors. Investigating with the LLM it deduced the build errors were from not having fallbacks so I took it's word. Adding them appeared to resolve the errors 🤷

[KoolADE85]

@KoolADE85 I added fallback values because I was getting build errors. Investigating with the LLM it deduced the build errors were from not having fallbacks so I took it's word. Adding them appeared to resolve the errors 🤷

hmm, I don't see any build errors when I remove them - do you recall what the error was? I'm wondering if it was just a hallucinated fix.
Or maybe even related to the build errors we encountered the other day 🤔

[jasonpnp]

If the build errors are gone even without them maybe it was something else? That was the only reason I added them