Please see the steps below to create a new table style rule, and apply the new rule to the table:
1. Create a New Table Style Rule
Step 1: Click anywhere in the table;
Step 2: Click the Home Tab from the Ribbon;
Step 3: Click "Format as Table" in the "Styles" area;
Step 4: Click "New Table Style" at the bottom;
Step 5: Select "Table Element" in the "New Table Style" window, then click Format button;
Step 6: Select the formatting style, click "OK";
2. Apply the New Rule to the Table
Step 7: Click the "Format as Table" in the Home Tab from the Ribbon, then select your custom style in the "Custom" section;
Step 8: You will see the new rule in the table.
