style.css

body {
    font-family: 'Courier New', Courier, monospace;
}

img {
    width: 300px;
    height: 300px;
    border-radius : 300px;
}

.hover-effect:hover {
   opacity: 0.8;
    cursor: pointer;
}

img:nth-of-type(2) {
    filter: grayscale(3);
}