style.css

* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    line-height: 0;
}

body {
    background-image: url(img/bg2.jpg);
    text-align: center;
    font-family: 'Slabo 27px', serif ;
}

header {
    background-color: black;
    padding: 5em;
    position: fixed;
    width: 300px;
    top: 100px;
}

h3 {
    color: white;
    font-variant: small-caps;
}

/* progress */
.main {
    background-color: white;
    opacity: 0.95;
    padding: 2em;
    position: absolute;
    width: 250px;
    top: 300px;
    right: 200px;
}

.guide {
    background-color: #ffc400;
    opacity: 0.95;
    padding: 2em;
    position: fixed;
    width: 250px;
    top: 260px;
    left: 0;
}

/* progress */

section {   
    width: 606px;
    margin: 5px auto;
    overflow: auto;
    background-color: white;
}

.btn {
    width: 200px;
    float: left;
    margin: 2px 1px;
}

.btn:hover {  
    opacity: 0.5;
}

.active {
    opacity: 0.5;
}