Accept CSS color formats supported by plotly.js in the color validator

CHANGELOG.md

@@ -24,6 +24,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Fix `mpl_to_plotly` conversion of matplotlib contour lines and line collections: close contour rings ending with `Z` codes, support dash styles, convert date x-axes, separate disjoint subpaths with `None` separators, hide line collection traces from the legend by default, and group consecutive same-style lines into single traces [[#5770](https://github.com/plotly/plotly.py/pull/5770)], with thanks to @robertoffmoura for the contribution!
 - Fix `plotly.io.write_images` ignoring `layout.width`/`layout.height` (and the template's) and exporting every figure at the default 700x500 size; it now uses the same width/height priority as `write_image` and `to_image` [[#5784](https://github.com/plotly/plotly.py/pull/5784)], with thanks to @breken-ai for the contribution!
 - Fix color utilities mutating the list of colors passed to them [[#5836](https://github.com/plotly/plotly.py/pull/5836)], with thanks to @Enesuygurs for the contribution!
+- Accept CSS color formats that plotly.js supports but the color validator rejected, such as negative `lab()`/`oklab()` components, `color()` values, angle units other than `deg`, the `none` keyword and `transparent` [[#5868](https://github.com/plotly/plotly.py/pull/5868)], with thanks to @ShawnNotFound for the contribution!
 
 
 ## [7.1.0] - 2026-09-15

_plotly_utils/basevalidators.py

@@ -1138,13 +1138,24 @@ class ColorValidator(BaseValidator):
     },
     """
 
-    re_spaces_to_remove = re.compile(r"(?<!(\d|%|g)) | (?!\d)")
-
     re_hex = re.compile(
         r"#([A-Fa-f0-9]{3}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{8})"
     )
+
+    # A CSS color function argument: a number (which may be signed or use an
+    # exponent) with an optional percent sign or angle unit, or `none`.
+    _re_css_value = (
+        r"(?:[+-]?(?:\d+\.?\d*|\.\d+)(?:e[+-]?\d+)?(?:%|deg|grad|rad|turn)?|none)"
+    )
+    _re_css_sep = r"(?:\s*,\s*|\s+)"
+    _re_css_alpha_sep = r"(?:\s*[,/]\s*|\s+)"
     re_rgb_etc = re.compile(
-        r"((rgb|hsl)a?|hwb|(ok)?(lab|lch))\([\d.]+(%|deg)?([ ,] ?[\d.]+%?){2}([ /,] ?[\d.]+%?)?\)|color\([\w-]+([ ,] ?[\d.]+){3,4}\)"
+        r"(?:(?:rgb|hsl)a?|hwb|(?:ok)?(?:lab|lch))\s*\(\s*"
+        rf"{_re_css_value}{_re_css_sep}{_re_css_value}{_re_css_sep}{_re_css_value}"
+        rf"(?:{_re_css_alpha_sep}{_re_css_value})?\s*\)"
+        r"|color\s*\(\s*[a-z][\w-]*"
+        rf"(?:{_re_css_sep}{_re_css_value}){{3}}"
+        rf"(?:{_re_css_alpha_sep}{_re_css_value})?\s*\)"
     )
     re_ddk = re.compile(r"var\(\-\-.*\)")
 
@@ -1290,6 +1301,7 @@ class ColorValidator(BaseValidator):
         "teal",
         "thistle",
         "tomato",
+        "transparent",
         "turquoise",
         "violet",
         "wheat",
@@ -1443,12 +1455,7 @@ def perform_validate_coerce(v, allow_number=None):
             # If not allow_numbers then value must be a string
             return None
         else:
-            # Remove spaces so regexes don't need to bother with them.
-            # Don't remove spaces between two digits, though.
-            v_normalized = v.strip()
-            v_normalized = re.sub(" +", " ", v_normalized)
-            v_normalized = re.sub(ColorValidator.re_spaces_to_remove, "", v_normalized)
-            v_normalized = v_normalized.lower()
+            v_normalized = v.strip().lower()
 
             # if ColorValidator.re_hex.fullmatch(v_normalized):
             if fullmatch(ColorValidator.re_hex, v_normalized):

tests/test_plotly_utils/validators/test_color_validator.py

@@ -57,6 +57,18 @@ def validator_aok_colorscale():
     "lab(70 15 50)",
     "lch(70 15 180)",
     "color(display-p3 1 0 0)",
+    "color(srgb 1 0 0)",
+    "color(a98-rgb 1 0 0 / 0.5)",
+    "lab(50% -40 59.5)",
+    "oklab(0.6 0.1 -0.05)",
+    "lch(52% 72 -30)",
+    "hsl(-30, 50%, 50%)",
+    "hsl(0.5turn 60% 40%)",
+    "hsl(1rad 60% 40%)",
+    "hsl(none 60% 40%)",
+    "rgb(255 0 0 / none)",
+    "rgb(1e2, 0, 0)",
+    "transparent",
 ]
 
 INVALID_COLORS_WRONG_TYPE = [
@@ -72,6 +84,12 @@ def validator_aok_colorscale():
     "hsl(0, 1%0000%, 50%)",
     "hsv(0, 100%, 100%)",
     "hsva(0, 100%, 100%, 50%)",
+    "currentcolor",
+    "rgb(255, 0)",
+    "rgb(255 0 0 /)",
+    "rgb(1-2 3 4)",
+    "color(1 0 0)",
+    "color(srgb 1 0)",
 ]