* {
    box-sizing: border-box;
}
  
body {
    font-family: "Open Sans",
    sans-serif; 
    font-size: 20px;
    color: #444;
    text-align: center;
    line-height: 1.5;
    margin: 20px;
}

body .index {
    text-align: left;
}
  
nav,
footer {
    padding: 1% 0;
    background-color: #aaa;
}
  
nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 10;
}
  
header {
    padding: 12% 0;
}

.login header,
.registration header,
.drum-machine header {
    padding: 12% 0 0 0;
}
  
section {
    min-height: 200px;
    padding: 6% 0;
    background-color: #bbb;
}
  
section:nth-child(even) {
    background-color: #ddd;
}

ul {
    list-style-type: none;
    padding: 0;
}

form {
    padding: 0 0 12% 0;
}

#textTempo {
    width: 40px;
}

.controls-tempo {
    padding: 0 0 4% 0;
}

.controls-file,
.instrument-selector {
    padding: 4% 0 4% 0;
}

.instrument {
    padding: 10px 0 10px 0;
}

.note {
    font-size: 0.8em;
    color: rgba(0, 0, 0, 0.5);
}

.list-spacer {
    padding: 10px;
}