Child Theme

Leadinjection Wordpress Theme comes with a Child Theme ready to be used.
Simply install the leadinjection-child.zip and activate the Child Theme just like a regular theme after you have installed Leadinjection.

A child theme is a theme that inherits the functionality and styling of another theme, called the parent theme. Child themes are the recommended way of modifying an existing theme. Child themes allow you to modify or add to the functionality of the existing parent theme.

Always use a Child Theme when modifying any theme files. This way you make sure a theme update will not wipe out any changes you have made to the files.
There are a few reasons why you would want to use a child theme: If you modify a theme directly and it is updated, then your modifications may be lost. By using a child theme you will ensure that your modifications are preserved.

Read more on Modifying your Theme and using Child Themes here.