style.css

* { font-family: sans-serif; font-weight: 600 }

body { margin: 0; background-color: #f0f0f0; }

.order, .nav p {
  display: inline;
  cursor: pointer;
  font-size: 17px;
  margin: 0 0 0 30px;
}

.active, .nav p:hover { color: #323220; text-decoration: underline; }

.nav {
  width: 100%;
  padding: 20px 0px 20px 0px;
  background-color: hsl(206, 27%, 61%);
}

.nav p:nth-of-type(1) { padding-right: 30px; border-right: 2px solid black; }

.content { text-align: center; }

#can0 {
  display: block;
  border-top: 2px solid black;
  border-bottom: 2px solid black;
  background-color: #f0f0f0;
  margin: auto;
}

.btn {
  display: inline;
  font-size: 28px;
  border: 2px solid black;
  background-color: white;
  border-radius: 5px;
  cursor: pointer;
  margin: 10px 10px 10px 0;
}

#btn1 { padding: 10px 25px 10px 25px; }

.pulse { animation: pulse .3s infinite; }

#rainbowSelectParagraph { 
  display: inline;
  border-radius: 5px;
  background: linear-gradient(45deg, red, orange, yellow, green, blue, indigo, violet); 
}

#rainbowSelect { display: inline-block; padding: 9px 9px 9px 9px; }

.slider {
  -webkit-appearance: none;
  width: 100px;
  height: 15px;
  border-radius: 5px;
  background: #d3d3d3;
  opacity: 0.7;
  -webkit-transition: .2s;
  transition: opacity .2s;
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 25px;
  height: 25px;
  border-radius: 50%; 
  background: #00cc00;
  cursor: pointer;
}

.slider::-moz-range-thumb {
  width: 25px;
  height: 25px;
  border-radius: 50%;
  background: #00cc00;
  cursor: pointer;
}

.slider:nth-of-type(1) { margin-right: 25px; }

.slider:hover { opacity: 1; }

.sizeNspeed { display: inline-block; }

.sizeNspeed:nth-of-type(3) { margin-left: 15px; }

.noselect {
  -webkit-touch-callout: none; /* iOS Safari */
    -webkit-user-select: none; /* Safari */
     -khtml-user-select: none; /* Konqueror HTML */
       -moz-user-select: none; /* Old versions of Firefox */
        -ms-user-select: none; /* Internet Explorer/Edge */
            user-select: none;
}

@-webkit-keyframes pulse {
  0%   { -webkit-box-shadow: 0 0 0 0 rgba(255, 0, 0, 0.5); }
  70%  { -webkit-box-shadow: 0 0 0 20px rgba(255, 0, 0, 0); }
  100% { -webkit-box-shadow: 0 0 0 0 rgba(255, 0, 0, 0); }
}

@keyframes pulse {
  0% {
    -moz-box-shadow: 0 0 0 0 rgba(255, 0, 0, 0.5);
    box-shadow: 0 0 0 0 rgba(255, 0, 0, 0.5);
  }
  70% {
    -moz-box-shadow: 0 0 0 10px rgba(255, 0, 0, 0);
    box-shadow: 0 0 0 20px rgba(255, 0, 0, 0);
  }
  100% {
    -moz-box-shadow: 0 0 0 0 rgba(255, 0, 0, 0);
    box-shadow: 0 0 0 0 rgba(255, 0, 0, 0);
  }
}