I need to add up-right triangle in a cell.

How to do this?
I t
Using CSS Triangles:
You basically have a 0 height, 0 width element, and use the borders to construct the triangle. Because the line between borders (for example, between top and left) is diagonal, you can create nice looking, solid color triangles with it!
Here's an Example!
Triangle!
No Triangle!
td {
padding: 20px;
}
.note {
position: relative;
}
.note:after { /* Magic Happens Here!!! */
content: "";
position: absolute;
top: 0;
right: 0;
width: 0;
height: 0;
display: block;
border-left: 20px solid transparent;
border-bottom: 20px solid transparent;
border-top: 20px solid #f00;
} /* */
in your HTML, instead of relying on :after.