Insert a Horizontal Line in a Notebook
Add lines to notebooks to delimit headers and blocks of content.
In a Single Cell...
With the selection in the cell you want to add a line to, choose the position and thickness of the line from the menu:
- Some styles of cells—for example, Section cells—contain lines by default.
Across a Whole Notebook...
Right-click between cells and choose a line style from the item in the popup menu: