[guides-] give guides the same background colour as sidebar

Finding formatting colours that are visible on both styles of background
of the sidebar and guides
has been challenging. This is the approach of consolidating them to the
same colour.

visidata/guide.py

@@ -8,7 +8,7 @@
 import re
 
 from visidata import vd, BaseSheet, Sheet, ItemColumn, Column, VisiData, ENTER, RowColorizer, AttrDict, MissingAttrFormatter
-from visidata import wraptext, Path
+from visidata import wraptext, Path, CellColorizer
 
 guides_list = '''
 GuideIndex ("A Guide to VisiData Guides (you are here)")
@@ -160,6 +160,7 @@ class GuideSheet(Sheet):
             ItemColumn('guide', 1, width=80, displayer='full'),
             ]
     precious = False
+    colorizers = [CellColorizer(4, 'color_sidebar', lambda s,c,r,v: True)]
 
     def iterload(self):
         self.metadata = AttrDict(sheettype='Sheet')