Theme Horse

Hi Ciubo_4ever,

To have a 100% width of the slider to your screen size first you have to choose image slider where you can upload max width images and
Go to Appearance > Customize/Theme Options > Design Options Tab > Custom CSS paste the following CSS code and Click on save button:

.featured-slider .slider-cycle .slides a img {
    width: 100%;
}

Thank you for using our theme.