*, *:before, *:after {
  box-sizing: border-box;
}

body {
  font-family: Trebuchet, Arial, sans-serif;
}

#root {
  position: fixed;
  width: 100%;
  background-image: url(../images/background.jpg);
  background-size: cover;
  background-blend-mode: darken;
  height: 100%;
  top: 0;
  left: 0;
}

nav {
  text-align: center;
  background: #3198f1;
  color: #ecf0f1;
  padding: 4px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.4);
  position: relative;
}

.btn {
  display: block;
  padding: 12px;
  overflow: hidden;
  border-width: 0;
  outline: none;
  border-radius: 2px;
  box-shadow: 1px 2px 5px rgba(0, 0, 0, 0.3);
  background-color: #2196F3;
  color: #ecf0f1;
}

.btn.btn-control-clock {
  position: fixed;
  right: 20px;
  bottom: 20px;
}

.btn:hover, .btn:focus {
  background-color: #42A5F5;
}

.btn span {
  display: block;
  padding: 12px 24px;
}

.btn:before {
  content: "";
  
  position: absolute;
  top: 50%;
  left: 50%;
  
  display: block;
  width: 0;
  padding-top: 0;
    
  border-radius: 100%;
  
  background-color: rgba(236, 240, 241, .3);
  
  -webkit-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
}

.btn:active:before {
  width: 120%;
  padding-top: 120%;
  
  -webkit-transition: width .2s ease-out, padding-top .2s ease-out;
  
  transition: width .2s ease-out, padding-top .2s ease-out;
}

.btn.orange {
  background-color: #e67e22;
}

.btn.orange:hover, .btn.orange:focus {
  background-color: #d35400;
}

.btn.red {
  background-color: #e74c3c;
}

.btn.red:hover, .btn.red:focus {
  background-color: #c0392b;
}