You can customize the 404 Page as you like. Follow Theme Options > General Settings. Here click 404 Page, and the 404-page fields will appear.
Custom 404 Style: Switch on to add custom 404 page style.
Page Title: Set Custom Page Title.
Page Sub-Title: Set Custom Page Sub-Title.
Button Before Text: Set Custom Button Before Text.
Button Text: Set Custom Button Text.
Background: Set Custom page background.
Background Overlay: Enable to add overlay in the background.
Overlay Color: Set overlay color.
Overlay Opacity: Set overlay opacity.
Title Color: Set Custom Title Color.
Sub-Title Color: Set Custom Sub-Title Color.
Before Button Text Color: Set Before Button Text Color.
Before Button Color: Set Before Button Color.
Before Button Hover Color: Set Before Button Hover Color.
Click Save Changes to save theme options. Click Reset Section to reset only this section. Click Reset All to reset all theme options.