body {
  font-size: 16px;
  margin: 0;
  padding: 0;
}

div {
  display: flex;
  flex-wrap: nowrap;
  flex-direction: row;
  justify-content: center;
  align-items: stretch;
  align-content: space-between
    flex-basis: auto;
    flex-shrink: 1;
    flex-grow: 1;
  flex: 1 0 auto;
  margin: 10px;
}

.row {
    flex-flow: row;
    justify-content: row;
    flex-direction: row;
}

.col {
    flex-flow: column;
    justify-content: center;
    flex-direction: column;
}

.spacer {
    flex-grow: 1;
}

.ranges {
  min-height: 69vh;  
}

label {
  display: block;
  margin: 0;
  position: absolute;
}

input[type="range"] {
    display: block;
    height: 100%;
    width: calc(100% + 12px);
    -webkit-appearance: none;
    margin: 0;
    appearance: slider-vertical;
    accent-color: #5ddcff;
    border-radius: 9px;
    overflow: hidden;
}

input[type="range"]:focus {
  outline: none;
}

input[type="range"]::-webkit-slider-runnable-track {
  width: 100%;
  height: 100%;
  background-color: #191c29;
  border-radius: 6px;
  border: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 100%;
  height: 30px;
  background-color: transparent;
  border-radius: 6px;
  border: 2px solid #ccc;
  margin-top: -12px;
  min-width: 100%;
}

input[type="range"]:focus::-webkit-slider-runnable-track {
  width: 100%;
  background-color: #191c29;
}

input[type="range"]::-webkit-slider-thumb:active {
  background-color: #191c29;
  width: 100%;

}

button {
  display: block;
  width: 100%;
  height: 50px;
  font-size: 20px;
  background: #ccc;
  border: none;
  border-radius: 5px;
  margin-top: 10px;
}

button:focus {
  outline: none;
}

#currentFreq {
  font-size: 20px;
  font-weight: bold;
  margin-top: 10px;
}

/* https://codepen.io/gayane-gasparyan/pen/jOmaBQK  */

@property --rotate {
  syntax: "<angle>";
  initial-value: 132deg;
  inherits: false;
}

:root {
  --card-height: 80vh;
/*  --card-width: calc(var(--card-height) / 1.5); */
  --card-width: 28vw;
}

body {
  min-height: 100vh;
  background: #212534;
  display: flex;
  align-items: center;
  flex-direction: column;
  font-family: monospace;
  font-weight: bold;
  font-size: 16px;
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  color: rgb(88 199 250 / 42%);
}

.card {
    /* background: #191c29; */
    width: var(--card-width);
    height: var(--card-height);
    padding: 0;
    position: relative;
    border-radius: 6px;
    justify-content: center;
    align-items: center;
    text-align: center;
    display: flex;
    color: rgb(88 199 250 / 90%);
}

.card:hover {
  color: rgb(88 199 250 / 30%);
  transition: color 1s;
}
.card:hover:before, .card:hover:after {
/*  animation: none; */
  opacity: 1;
  transition: opacity 1s;
}

.card::before {
  content: "";
  width: 104%;
  height: 102%;
  border-radius: 9px;
  opacity: 0.5;
  background-image: linear-gradient(
    var(--rotate)
    , #5ddcff, #3c67e3 43%, #4e00c2);
    position: absolute;
    z-index: -1;
    top: -1%;
    left: -2%;
    animation: spin 2.5s linear infinite;
}

.card::after {
  position: absolute;
  content: "";
  top: calc(var(--card-height) / 6);
  left: 0;
  right: 0;
  z-index: -1;
  height: 100%;
  width: 100%;
  margin: 0 auto;
  opacity: 0.5;
  transform: scale(0.8);
  filter: blur(calc(var(--card-height) / 6));
  background-image: linear-gradient(
    var(--rotate)
    , #5ddcff, #3c67e3 43%, #4e00c2);
    opacity: 1;
  transition: opacity .5s;
  animation: spin 2.5s linear infinite;
}

@keyframes spin {
  0% {
    --rotate: 0deg;
  }
  100% {
    --rotate: 360deg;
  }
}

a {
  color: rgb(88 199 250 / 100%);
  transition: color 1s;
  text-decoration: none;
}