Trabalhando com imagens de fundo
background-image: url("../img/background-01.jpg");
background-image: url("../img/logo.png"), url("../img/background-01.jpg");
background-image: linear-gradient(to right, red, purple, blue);
background-image: radial-gradient(circle, red, purple, blue);
background-image: repeating-linear-gradient(to top, palevioletred 0 20px, lightpink 20px 40px, lightgreen 40px 60px);