seven/css/custom.css

body {
    height: 100vh;
    width: 100vw;

    margin: 0;
    padding: 0;

    background: url("../img/wallpaper.jpg");
    background-size: cover;
    background-position: center;
}

.window {
    position: absolute;
    overflow: hidden;
    height: 300px;
    width: 500px;
    top: 16px;
    left: 16px;
}

.window.active {
    z-index: 2;
}

.window-body {
    padding: 8px 12px;
    height: calc(100% - 52px);
    width: calc(100% - 38px);
    overflow: auto;
}

h1,h2,h3,h4,h5,h6,p {
    margin: 0;
}