:root {
  color-scheme: dark;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #090c14;
  color: #f2f5ff;
}

* {
  box-sizing: border-box;
}

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  overflow: hidden;
}

button,
input {
  font: inherit;
}

.signal {
  position: relative;
  display: grid;
  min-height: 100vh;
  place-items: center;
  padding: 24px;
  isolation: isolate;
  background:
    radial-gradient(circle at 50% 50%, #252b41 0, #111624 31%, #090c14 71%);
}

.wave {
  position: absolute;
  width: min(78vmin, 760px);
  aspect-ratio: 1;
  border: 1px solid rgb(183 199 255 / 18%);
  border-radius: 50%;
  pointer-events: none;
}

.wave--one {
  animation: pulse 3.4s ease-out infinite;
}

.wave--two {
  animation: pulse 3.4s 1.7s ease-out infinite;
}

.panel {
  width: min(100%, 530px);
  padding: clamp(32px, 6vw, 56px);
  text-align: center;
  background: rgb(15 20 34 / 76%);
  border: 1px solid rgb(220 228 255 / 16%);
  border-radius: 28px;
  box-shadow: 0 28px 80px rgb(0 0 0 / 30%);
  backdrop-filter: blur(16px);
  z-index: 1;
}

.eyebrow {
  margin: 0 0 22px;
  color: #b7c7ff;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(2.4rem, 8vw, 4.8rem);
  font-weight: 760;
  letter-spacing: -0.07em;
  line-height: 0.94;
}

.status {
  min-height: 2.8em;
  margin: 22px auto 28px;
  color: #c6cbdb;
  font-size: 1rem;
  line-height: 1.45;
}

.start-button {
  width: 100%;
  padding: 15px 22px;
  color: #090c14;
  font-weight: 750;
  cursor: pointer;
  background: #d9e2ff;
  border: 0;
  border-radius: 14px;
  box-shadow: 0 8px 30px rgb(174 193 255 / 25%);
}

.start-button:hover {
  background: #fff;
}

.controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  margin-top: 24px;
  padding-top: 24px;
  border-top: 1px solid rgb(220 228 255 / 12%);
}

.control {
  padding: 0;
  color: #f2f5ff;
  cursor: pointer;
  background: none;
  border: 0;
  text-decoration: underline;
  text-decoration-color: rgb(242 245 255 / 38%);
  text-underline-offset: 4px;
}

.volume-control {
  display: grid;
  grid-template-columns: auto 96px;
  align-items: center;
  gap: 10px;
  color: #c6cbdb;
  font-size: 0.85rem;
}

input[type="range"] {
  width: 96px;
  accent-color: #d9e2ff;
  cursor: pointer;
}

.note {
  margin: 27px 0 0;
  color: #858da5;
  font-size: 0.78rem;
  line-height: 1.45;
}

button:focus-visible,
input:focus-visible {
  outline: 3px solid #96b0ff;
  outline-offset: 4px;
}

@keyframes pulse {
  0% {
    opacity: 0;
    transform: scale(0.22);
  }
  20% {
    opacity: 0.95;
  }
  100% {
    opacity: 0;
    transform: scale(1.22);
  }
}

@media (max-width: 480px) {
  .panel {
    padding: 34px 24px;
  }

  .controls {
    align-items: flex-start;
    flex-direction: column;
  }
}

@media (prefers-reduced-motion: reduce) {
  .wave {
    animation: none;
    opacity: 0.4;
  }
}