Migrate GUI colors test to original CSS color format

[GuillaumeGomez]

Follow-up of #111459.

r? @notriddle

[notriddle]

@bors r+ rollup

[bors]

📌 Commit 344ac25 has been approved by notriddle

It is now in the queue for this repository.

[bors]

⌛ Testing commit 344ac25 with merge 8e37c50...

[bors]

☀️ Test successful - checks-actions
Approved by: notriddle
Pushing 8e37c50 to master...

[rust-timer]

Finished benchmarking commit (8e37c50): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.4%	[0.4%, 0.4%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.4%	[0.4%, 0.4%]	2

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 630.365s -> 631.343s (0.16%)
Artifact size: 318.00 MiB -> 318.07 MiB (0.02%)