diff --git a/src/bonsai/bonsai/tool/web.py b/src/bonsai/bonsai/tool/web.py
index 66847f0c03..7ab178bde7 100644
--- a/src/bonsai/bonsai/tool/web.py
+++ b/src/bonsai/bonsai/tool/web.py
@@ -28,7 +28,8 @@ import bonsai.tool as tool
 import ifcopenshell.api.sequence
 import ifcopenshell.api.classification
 import ifcopenshell.api.cost
-from typing import Any, Optional, TYPE_CHECKING
+from typing import Any, Optional, TYPE_CHECKING, Union
+from mathutils import Color
 import time
 import socket
 import sys
@@ -790,8 +791,8 @@ class Web(bonsai.core.tool.Web):
         calculates the mixed colors, and sends the theme data to the Web UI.
         """
 
-        def get_color(theme, attribute) -> tuple[Any, ...]:
-            return tuple(getattr(theme, attribute)[:])
+        def to_tuple(theme: Union[Color, bpy.types.bpy_prop_array[float]]) -> tuple[float, ...]:
+            return tuple(theme[:])
 
         def mix_colors(color1, color2):
             alpha1 = color1[3] * 255 if len(color1) > 3 else 255
@@ -803,33 +804,50 @@ class Web(bonsai.core.tool.Web):
             blue = (color1[2] * (255 - alpha2) + color2[2] * alpha2) / 255
             return red, green, blue, alpha / 255
 
-        prefs = bpy.context.preferences.themes[0].preferences.space
-        panel = prefs.panelcolors
-        view_3d = bpy.context.preferences.themes[0].view_3d
-        top_bar = bpy.context.preferences.themes[0].topbar.space
-        info = bpy.context.preferences.themes[0].info
-        outliner = bpy.context.preferences.themes[0].outliner
-        ui = bpy.context.preferences.themes[0].user_interface
+        assert (blender_preferences := bpy.context.preferences)
+        blender_theme = blender_preferences.themes[0]
+        prefs = blender_theme.preferences.space
+
+        if tool.Blender.BLENDER_5 or TYPE_CHECKING:
+            theme_ui = blender_theme.user_interface
+            theme_regions = blender_theme.regions
+            panel_header, panel_back, panel_sub_back = (
+                theme_ui.panel_header,
+                theme_ui.panel_back,
+                theme_ui.panel_sub_back,
+            )
+            tab_back, tab_outline = theme_regions.sidebars.tab_back, theme_ui.wcol_tab.outline
+        else:
+            # Removed in Blender 5.0.
+            panel = prefs.panelcolors
+            tab_back, tab_outline = prefs.tab_back, prefs.tab_outline
+            panel_header, panel_back, panel_sub_back = panel.header, panel.back, panel.sub_back
+
+        view_3d = blender_theme.view_3d
+        top_bar = blender_theme.topbar.space
+        info = blender_theme.info
+        outliner = blender_theme.outliner
+        ui = blender_theme.user_interface
 
         theme = {
-            "window_background": get_color(prefs, "back"),
-            "text": get_color(prefs, "text"),
-            "tab_background": get_color(prefs, "tab_back"),
-            "tab_outline": get_color(prefs, "tab_outline"),
-            "panel_header": get_color(panel, "header"),
-            "panel_background": mix_colors(get_color(panel, "back"), get_color(panel, "sub_back")),
-            "top_bar_header": get_color(top_bar, "header"),
-            "top_bar_header_text": get_color(top_bar, "header_text"),
-            "active_object": get_color(view_3d, "object_active"),
-            "selected_object": get_color(view_3d, "object_selected"),
-            "info_warning": get_color(info, "info_warning_text"),
-            "odd_row": get_color(outliner.space, "back"),
-            "even_row": mix_colors(get_color(outliner.space, "back"), get_color(outliner, "row_alternate")),
-            "active_highlight": get_color(outliner, "active"),
-            "active_text_highlight": get_color(outliner, "active_object"),
-            "button_background": get_color(ui.wcol_tool, "inner"),
-            "button_test": get_color(ui.wcol_tool, "text"),
-            "button_border": get_color(ui.wcol_tool, "outline"),
+            "window_background": prefs.back[:],
+            "text": to_tuple(prefs.text),
+            "tab_background": to_tuple(tab_back),
+            "tab_outline": to_tuple(tab_outline),
+            "panel_header": to_tuple(panel_header),
+            "panel_background": mix_colors(to_tuple(panel_back), to_tuple(panel_sub_back)),
+            "top_bar_header": to_tuple(top_bar.header),
+            "top_bar_header_text": to_tuple(top_bar.header_text),
+            "active_object": to_tuple(view_3d.object_active),
+            "selected_object": to_tuple(view_3d.object_selected),
+            "info_warning": to_tuple(info.info_warning_text),
+            "odd_row": to_tuple(outliner.space.back),
+            "even_row": mix_colors(to_tuple(outliner.space.back), to_tuple(outliner.row_alternate)),
+            "active_highlight": to_tuple(outliner.active),
+            "active_text_highlight": to_tuple(outliner.active_object),
+            "button_background": to_tuple(ui.wcol_tool.inner),
+            "button_test": to_tuple(ui.wcol_tool.text),
+            "button_border": to_tuple(ui.wcol_tool.outline),
         }
         cls.send_webui_data(theme, "theme", "theme_data", use_web_data=False)