# Diagonal formatting of grid / table

I have a table given by (a simple example for clarity)

Grid[
Prepend, {Prepend[
Table[1, {m, 0, 10}, {x, 0, 10}], {"x=0", "1", "2", "3", "4", "5",
"6", "7", "8", "9", "10"}], {"Table", "m=0", "1", "2", "3", "4",
"5", "6", "7", "8", "9", "10"}}],
Frame -> {{True}, {True}}]/. 1 -> Style[1, Bold, Red]


It's just a grid of 1s with all 1 highlighted in red. But what I want to know is how do I:

1. Create a downwards-diagonal line across the grid at x=m?
2. Turn the font style to grey for all items above that line, thus over-riding the Bold, Red instruction (not for values on the line, for values above it - i.e., for all x>m)?

• Also, can I then label that line? Aug 15 '18 at 15:31

This does some of what you request. Style can be applied at quite low levels of the expression
Grid[MapThread[