CSS rules to center image slider

[doog_2019]

Hi 😃,

I am a begginer and I use Prestashop 1.7. My website is: Goodbrand.fr

On desktop and tablets my slider is good but on MOBILE, it is to small as you can see on the photo:

My question: How can my slider be center on each screen size ? 

What I have done in localhost: 

@media (min-width: 321px) and (max-width: 500px) {

#index .nivoSlider img {
left: -320px
}

#index .nivo-main-image {
    display: block !important;
    position: relative !important;
    width: 290% !important;

THIS IS THE RESULT I WANT ON ALL MOBILES

 

THIS IS THE RESULTAT I HAVE WHEN I CHANGE THE SIZE OF THE SCREEN

 

Thank you for your help, 

😎

Edited May 17, 2019 by doog_2019 (see edit history)

[doog_2019]

I edited my message to try to be more understood..

Do not hesitate to ask me more details