Question: On the single images there is an animation by default with color  #C59D5F , that moves from the one side to the other, how can i change that color?

style.css line 3111

.img-wrapper:after {
    content: '';
    margin: 0 -5px 0 0;
    position: absolute;
    top: 0;
    right: 100%;
    bottom: 100%;
    left: 0;
    background: #c59d5f;
    z-index: 3;
    transition: bottom 0.4s cubic-bezier(0.165, 0.84, 0.44, 1) 0s, right 0.4s cubic-bezier(0.77, 0, 0.175, 1) 0.3s, margin 0.4s cubic-bezier(0.77, 0, 0.175, 1) 0.3s, left 0.4s cubic-bezier(0.77, 0, 0.175, 1) 0.6s; 
}

or you can override via Appearance > Customize > Additional CSS field just like;

.img-wrapper:after {
    background: red;
}