I used the provided following CSS code on your site and the size of it reduces as shown in the attached screenshot so could you please try using it again?

.single-fw-portfolio .sh-ratio-content {
    max-width: 1000px;
    background-size: 100%;
    background-repeat: no-repeat;
    margin: 0 auto;
    height: 620px;
}

.single-fw-portfolio  .sh-ratio-container {
    padding-bottom: 0;
}