style.css

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600&display=swap');

:root {
  --bg-gradient: linear-gradient(135deg, #181a20 0%, #23243a 100%);
  --card-bg: rgba(30, 32, 40, 0.55);
  --card-border: rgba(255, 255, 255, 0.12);
  --card-shadow: 0 16px 32px rgba(0, 0, 0, 0.18), 0 8px 16px rgba(0, 0, 0, 0.10);
  --card-inner-shadow: 0 1px 8px 0 rgba(255, 255, 255, 0.08) inset;
  --text-color: #fff;
  --distance-gradient: linear-gradient(90deg, #5fb8ff, #00e1ff);
  --arrow-glow-start: rgba(95, 184, 255, 0.5);
  --arrow-glow-mid: rgba(95, 184, 255, 0.35);
}

body {
  margin: 0;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background: var(--bg-gradient);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  color: var(--text-color);
  position: relative;
  overflow: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  cursor: none;
}

/* === Card Container === */
.card {
  background: linear-gradient(135deg, rgba(255,255,255,0.18) 0%, rgba(30,32,40,0.45) 100%) padding-box, var(--card-bg);
  border-radius: 48px;
  box-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.18), 0 1.5px 8px 0 rgba(255,255,255,0.10) inset;
  border: 1.5px solid rgba(255,255,255,0.28);
  backdrop-filter: blur(24px) saturate(180%);
  -webkit-backdrop-filter: blur(24px) saturate(180%);
  width: 520px;
  max-width: 520px;
  min-width: 0;
  height: 520px;
  max-height: 520px;
  min-height: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 64px;
  text-align: center;
  position: relative;
  z-index: 1;
  transition: transform 0.18s cubic-bezier(.4, 0, .2, 1), background 0.3s, border 0.3s, box-shadow 0.3s;
  -webkit-user-select: none;
  user-select: none;
  overflow: hidden;
}
.card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: linear-gradient(120deg, rgba(255,255,255,0.22) 0%, rgba(255,255,255,0.08) 100%);
  pointer-events: none;
  z-index: 2;
}

/* === Arrow Section === */
#arrow-container {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 5rem;
  margin: 0 auto 20px auto;
  position: relative;
  z-index: 1;
}
#arrow {
  display: inline-block;
  width: 100%;
  height: 100%;
  max-width: 3.5rem;
  max-height: 3.5rem;
  transition: transform 0.8s cubic-bezier(.4, 0, .2, 1);
  position: relative;
  z-index: 1;
}
#arrow svg {
  width: 100%;
  height: 100%;
  stroke-width: 3.5;
  stroke-linecap: round;
  stroke-linejoin: round;
  filter: drop-shadow(0 0 8px var(--arrow-glow-start)) drop-shadow(0 0 20px var(--arrow-glow-mid));
}
#arrow.active {
  animation: pulseGlow 5s infinite cubic-bezier(.4, 0, .2, 1);
}

@keyframes pulseGlow {
  0%, 100% {
    filter: drop-shadow(0 0 8px var(--arrow-glow-start)) drop-shadow(0 0 20px var(--arrow-glow-mid));
  }
  50% {
    filter: drop-shadow(0 0 12px var(--arrow-glow-start)) drop-shadow(0 0 32px var(--arrow-glow-mid));
  }
}

/* === Distance Display === */
#distance {
  display: inline-flex;
  align-items: baseline;
  justify-content: center;
  font-size: 4rem;
  font-weight: 600;
  letter-spacing: 0.2px;
  background: var(--distance-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  transition: all 0.4s cubic-bezier(.4, 0, .2, 1);
  margin-bottom: 0.5rem;
  gap: 0.5rem;
}
#distance span.unit {
  font-weight: 500;
  font-size: 3rem;
  margin-left: 0.2rem;
  opacity: 1;
  background: none;
  color: #e6f7ff;
  text-shadow: 0 1px 6px rgba(95,184,255,0.18);
  display: inline-block;
  vertical-align: baseline;
}

/* === Details Section === */
#details {
  padding: 0.7rem 1rem 0.6rem 1rem;
  font-size: 1.6rem;
  font-weight: 500;
  color: var(--text-color);
  margin-top: 0.5rem;
  white-space: pre-line;
  transition: color 0.3s;
}
.details-flight,
.details-altitude,
.details-type,
.details-error,
.details-empty {
  font-size: 2rem;
  line-height: 1.3;
  margin-bottom: 0.3rem;
  display: block;
  transition: color 0.3s, opacity 0.3s;
}
.details-flight {
  font-weight: 700;
  letter-spacing: 0.5px;
}
.details-altitude {
  opacity: 0.85;
}
.details-type {
  opacity: 0.7;
}
.details-error {
  color: #d00;
  opacity: 0.8;
  font-weight: 500;
}
.details-empty {
  opacity: 0.7;
  font-weight: 500;
}

/* === Divider === */
.divider {
  width: 80%;
  height: 2px;
  background: linear-gradient(90deg, rgba(95,184,255,0.18), rgba(255,255,255,0.10), rgba(95,184,255,0.18));
  border-radius: 1px;
  margin: 1.2rem auto 1.2rem auto;
  box-shadow: 0 1px 4px rgba(95,184,255,0.08);
  transition: background 0.3s, box-shadow 0.3s;
}