style.css

body {
  width: 100vw;
  height: 100vh;
  margin: 0;
  overflow: hidden;

  display: grid;
  place-items: center;

  background-color: black;
  color: black;
  font-family: monospace;
  line-height: 1;
}

.backdrop {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-color: black;
  opacity: 0.5;
  z-index: -1;
}

.container {
  /*border: 4px solid red;*/
}

.modal {
  width: 475px;
  height: 310px;
  background-color: white;
  border-radius: 16px;
  display: flex;
  flex-direction: column;

  clip-path: circle(8% at calc(46% + 1px) calc(86% + 1px));
  transition: clip-path 0.3s ease-in-out;
}

.modal:not(.active) *:not(.record_btn) {
  pointer-events: none;
}

.record_btn {
  pointer-events: all;
}

.modal.active {
  clip-path: circle(100% at calc(46% + 1px) calc(86% + 1px));
}

button {
  background-color: transparent;
  font-family: monospace;
  padding: 0;
  cursor: pointer;
  border: 1px solid;
}

.btn {
  border-radius: 5px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 2px 2px 0 0 black;
  translate: 0 0;
  transition: all 50ms linear;
}

.btn:active {
  translate: 1px 1px;
  box-shadow: 0 0 0 0 black, 0 0 42px 10px #00000012;
}

.cancel {
  font-size: 19px;
  min-width: 24px;
  min-height: 24px;
}

.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px;
  border-bottom: 1px solid;
}

h1 {
  margin: 0;
  font-weight: normal;
  font-size: 24px;
  text-shadow: 1px 1px #0000005c;
}

form {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: 16px 12px;
}

label {
  font-size: 18px;
  margin-bottom: 7px;
  padding-left: 5px;
}

input {
  padding: 10px;
  font-size: 20px;
  font-family: monospace;
  outline: black;
  border: 1px solid;
  border-radius: 10px;
  box-shadow: 2px 2px 0 0 black;
}

.recording-container {
  padding: 15px 10px 0 10px;
}

.timer {
  margin-bottom: 7px;
}

.footer {
  flex: 1;
  margin-top: 10px;

  display: grid;
  grid-template-columns: repeat(13, 1fr);
  align-items: center;
  /*justify-content: center;*/
}

.record_btn {
  grid-column: 6 / span 2;
  border-radius: 50%;
  border: 1px;
  --w: 30px;
  height: var(--w);
  width: var(--w);
  background-color: black;
  justify-self: center;
  position: relative;
  translate: 0 1px;
  scale: 1;

  transition: scale 80ms linear;
}

.record_btn:active {
  scale: 0.8;
}

.record_btn::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  translate: -50% -50%;
  border-radius: 50%;
  width: 100%;
  height: 100%;
  background-color: transparent;
  border: 1px solid;
  z-index: 0;
  scale: 1.5;
  transition: scale 80ms linear;
}

.record_btn:active::after {
  scale: calc(1.5 / 0.8);
}

.footer .btn {
  padding: 7px 10px;
}

.resume_pause,
.reset {
  grid-column: 4 / span 2;
  justify-self: end;
  translate: 0 3px;
  border: none;
  --w: 30px;
  width: var(--w);
  height: var(--w);
}

.resume_pause > *,
.reset > * {
  width: 100%;
  height: 100%;
}

.reset {
  grid-column: 8 / span 2;
  justify-self: start;
}

.save {
  grid-column: 12 / span 2;
}

.waveform {
  /*border: 1px solid;*/
  width: 100%;
  height: 50px;
  position: relative;
  cursor: pointer;
}

.back-waveform,
.front-waveform {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  pointer-events: none;
}

.back-waveform > div,
.front-waveform > div {
  min-height: 5px;
  min-width: 1px;
  border-radius: 5px;
  background-color: black;
}

.back-waveform > div {
  background-color: #0000005c;
}

.front-waveform {
  transition: var(--transition, all 0.3s linear);
  clip-path: polygon(0% 0%, var(--dx, 0%) 0%, var(--dx, 0%) 100%, 0 100%);
}

.scrubber {
  width: 5px;
  height: 100%;
  position: absolute;
  left: 0;
  top: 0;
  background-color: black;
  border-radius: 5px;
  cursor: grab;
}

.scrubber:after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  translate: -50% -50%;
  width: 10px;
  height: 10px;
  border: 1px solid;
  border-radius: 2px;
  background-color: white;
}

.scrubber:active {
  cursor: grabbing;
}