You can use the user style sheet CSS to set the line spacing
Take epub as an example,
- Use the viewer to open the document
- Click "Preferences" in the toolbar below
- Select the "User Style Sheet" page and enter the following code:
body
{
line-height:1.5em;
}
- Click OK to exit. Right-click the book and select "Reload Book".
Some books do not take effect in this way because the internal settings of the book are used instead of the reader settings. If you want to force the use of the reader settings, you can add "!important" after the sentence. This will use the style display in the reader without changing the CSS of the original book.
body
{
line-height:1.5em !important;
}