How can I remove the White Border Inside Image

Hello great team, i have already set border with color #333333 but inside the image you can see other white border i want to delete this border how can i delete it? screenshot: https://www.dropbox.com/s/59r4rqqi6e1ws20/Screenshot%202018-02-03%2022.01.48.png?dl=0 website: tecnologino.com