style.css

* {
  margin: 0;
  padding: 0;
  -webkit-box-sizing: border-box;
          box-sizing: border-box;
  text-decoration: none;
  list-style: none;
}

body {
  height: 100%;
  overflow-y: scroll;
}

.black {
  width: 100%;
  min-height: -webkit-fill-available;
  height: 100vh;
  position: fixed;
  display: block;
  background-color: black;
  top: 0;
  left: 0;
  z-index: -12;
}

body:before {
  content: "";
  display: block;
  position: fixed;
  opacity: .5;
  left: 0;
  top: 0;
  width: 100%;
  min-height: -webkit-fill-available;
  height: 100vh;
  z-index: -10;
  background: url("img/background.jpg") no-repeat center center;
  background-size: cover;
}

header {
  margin: 20px 0;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
  -webkit-box-align: center;
      -ms-flex-align: center;
          align-items: center;
  height: -webkit-fit-content;
  height: -moz-fit-content;
  height: fit-content;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
      -ms-flex-direction: column;
          flex-direction: column;
}

.div_controls {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  width: -webkit-fit-content;
  width: -moz-fit-content;
  width: fit-content;
  height: -webkit-fit-content;
  height: -moz-fit-content;
  height: fit-content;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
      -ms-flex-direction: column;
          flex-direction: column;
  -webkit-transition: 1s;
  transition: 1s;
}

.div_controls_sub {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
      -ms-flex-direction: column;
          flex-direction: column;
  margin-right: 10px;
  position: relative;
}

.div_controls .div_controls_sub:nth-child(3) {
  margin-right: 0;
}

.div_controls_first_row, .div_controls_second_row {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
      -ms-flex-direction: column;
          flex-direction: column;
}

.inactive {
  opacity: 0;
  -webkit-transition: 1s;
  transition: 1s;
}

hr {
  margin-bottom: 20px;
  border: 0;
  height: 1px;
  background-image: -webkit-gradient(linear, left top, right top, from(rgba(255, 255, 255, 0)), color-stop(rgba(114, 114, 114, 0.75)), to(rgba(255, 255, 255, 0)));
  background-image: linear-gradient(to right, rgba(255, 255, 255, 0), rgba(114, 114, 114, 0.75), rgba(255, 255, 255, 0));
}

.color_picker {
  width: 40px;
  height: 40px;
  padding: 0;
  background: none;
  border-radius: 0;
  border: none;
  margin: 0;
  position: absolute;
  top: -5%;
  left: 60%;
}

#buzz_color, #both_color {
  top: 45%;
  left: 60%;
}

input {
  width: 180px;
  border-radius: 20px;
  background-color: lightblue;
  border: 1px solid black;
  margin-bottom: 20px;
  padding: 5px;
  padding-left: 10px;
}

input[type=checkbox] {
  height: 20px;
}

input::-webkit-input-placeholder {
  font-style: italic;
  padding-left: 10px;
  color: grey;
}

input:-ms-input-placeholder {
  font-style: italic;
  padding-left: 10px;
  color: grey;
}

input::-ms-input-placeholder {
  font-style: italic;
  padding-left: 10px;
  color: grey;
}

input::placeholder {
  font-style: italic;
  padding-left: 10px;
  color: grey;
}

label {
  background-color: firebrick;
  width: -webkit-fit-content;
  width: -moz-fit-content;
  width: fit-content;
  border-radius: 20px;
  padding: 5px;
  margin-bottom: 5px;
  border: 2px outset #ce502e;
}

.buttons {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-align: center;
      -ms-flex-align: center;
          align-items: center;
  margin-bottom: 20px;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
      -ms-flex-direction: column;
          flex-direction: column;
}

button {
  height: 40px;
  width: 130px;
  -webkit-box-shadow: inset 0px 1px 0px 0px #fff6af;
  box-shadow: inset 0px 1px 0px 0px #fff6af;
  background: -webkit-gradient(linear, left top, left bottom, color-stop(5%, #ffec64), to(#ffab23));
  background: linear-gradient(to bottom, #ffec64 5%, #ffab23 100%);
  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffec64', endColorstr='#ffab23',GradientType=0);
  background-color: #ffec64;
  border-radius: 6px;
  border: 1px solid #ffaa22;
  display: inline-block;
  cursor: pointer;
  color: #333333;
  font-size: 15px;
  font-weight: bold;
  padding: 6px 24px;
  text-shadow: 0px 1px 0px #ffee66;
  margin-bottom: 10px;
}

button:hover {
  -webkit-filter: grayscale(100%);
          filter: grayscale(100%);
}

.buttons button:nth-child(3) {
  margin-bottom: 0;
}

#error_messages {
  height: 80px;
  width: 300px;
  padding-left: 20px;
  color: firebrick;
  position: relative;
}

#error_messages::before {
  content: "Error messages";
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-pack: end;
      -ms-flex-pack: end;
          justify-content: flex-end;
  padding-right: 20px;
  padding-top: 10px;
  color: grey;
  font-style: italic;
}

#error_messages::after {
  content: "";
  /* border: 2px solid black; */
  -webkit-filter: blur(2px);
          filter: blur(2px);
  width: 100%;
  height: 100%;
  position: absolute;
  border-radius: 20px;
  top: 0;
  left: 0;
  background-color: rgba(136, 230, 172, 0.6);
  z-index: -1;
}

main {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
}

main section {
  display: -ms-grid;
  display: grid;
  -ms-grid-columns: 1fr;
      grid-template-columns: 1fr;
  grid-gap: 1em;
}

main div {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
  -webkit-box-align: center;
      -ms-flex-align: center;
          align-items: center;
  text-align: center;
  border: 1px solid black;
}

main div:hover {
  -webkit-transform: scale(0.8);
          transform: scale(0.8);
}

footer {
  width: 100%;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
  color: white;
  font-size: 2em;
  margin-top: 20px;
}

.div_class {
  background-color: rgba(207, 72, 142, 0.5);
}

.fizz_class {
  background-color: rgba(51, 115, 175, 0.5);
  -webkit-animation: spin 3s linear infinite;
          animation: spin 3s linear infinite;
}

.buzz_class {
  background-color: rgba(61, 211, 106, 0.5);
  -webkit-animation: spin_reverse 3s linear infinite;
          animation: spin_reverse 3s linear infinite;
}

.both_class {
  background-color: rgba(221, 93, 33, 0.5);
  -webkit-animation: pulse 3s linear infinite;
          animation: pulse 3s linear infinite;
}

.shadow {
  -webkit-box-shadow: 4px 4px 5px 0px rgba(0, 0, 0, 0.75);
          box-shadow: 4px 4px 5px 0px rgba(0, 0, 0, 0.75);
}

@-webkit-keyframes pulse {
  0% {
    opacity: 1;
  }
  50% {
    opacity: .2;
  }
  100% {
    opacity: 1;
  }
}

@keyframes pulse {
  0% {
    opacity: 1;
  }
  50% {
    opacity: .2;
  }
  100% {
    opacity: 1;
  }
}

@-webkit-keyframes spin {
  0% {
    -webkit-transform: rotate(0deg);
            transform: rotate(0deg);
  }
  25% {
    -webkit-transform: rotate(90deg);
            transform: rotate(90deg);
  }
  50% {
    -webkit-transform: rotate(180deg);
            transform: rotate(180deg);
  }
  75% {
    -webkit-transform: rotate(270deg);
            transform: rotate(270deg);
  }
  100% {
    -webkit-transform: rotate(360deg);
            transform: rotate(360deg);
  }
}

@keyframes spin {
  0% {
    -webkit-transform: rotate(0deg);
            transform: rotate(0deg);
  }
  25% {
    -webkit-transform: rotate(90deg);
            transform: rotate(90deg);
  }
  50% {
    -webkit-transform: rotate(180deg);
            transform: rotate(180deg);
  }
  75% {
    -webkit-transform: rotate(270deg);
            transform: rotate(270deg);
  }
  100% {
    -webkit-transform: rotate(360deg);
            transform: rotate(360deg);
  }
}

@-webkit-keyframes spin_reverse {
  0% {
    -webkit-transform: rotate(0deg);
            transform: rotate(0deg);
  }
  25% {
    -webkit-transform: rotate(-90deg);
            transform: rotate(-90deg);
  }
  50% {
    -webkit-transform: rotate(-180deg);
            transform: rotate(-180deg);
  }
  75% {
    -webkit-transform: rotate(-270deg);
            transform: rotate(-270deg);
  }
  100% {
    -webkit-transform: rotate(-360deg);
            transform: rotate(-360deg);
  }
}

@keyframes spin_reverse {
  0% {
    -webkit-transform: rotate(0deg);
            transform: rotate(0deg);
  }
  25% {
    -webkit-transform: rotate(-90deg);
            transform: rotate(-90deg);
  }
  50% {
    -webkit-transform: rotate(-180deg);
            transform: rotate(-180deg);
  }
  75% {
    -webkit-transform: rotate(-270deg);
            transform: rotate(-270deg);
  }
  100% {
    -webkit-transform: rotate(-360deg);
            transform: rotate(-360deg);
  }
}