@font-face {
  font-family: "Comfortaa";
  src: url("../Comfortaa-Light.ttf") format("truetype");
  font-weight: 300;
  font-style: normal;
  font-display: swap;
}

:root {
  --bg: #050611;
  --panel: rgba(8, 13, 31, 0.86);
  --panel-strong: rgba(11, 20, 48, 0.94);
  --text: #f4fbff;
  --muted: #93a6c9;
  --cyan: #26f7ff;
  --pink: #ff3df2;
  --violet: #8b5cff;
  --green: #71ffbf;
  --line: rgba(117, 247, 255, 0.28);
  --danger: #ff7aa8;
}

* {
  box-sizing: border-box;
}

html,
body {
  min-height: 100%;
}

body {
  margin: 0;
  color: var(--text);
  font-family: "Comfortaa", Arial, sans-serif;
  background:
    radial-gradient(circle at 18% 24%, rgba(38, 247, 255, 0.18), transparent 30%),
    radial-gradient(circle at 78% 18%, rgba(255, 61, 242, 0.16), transparent 28%),
    radial-gradient(circle at 50% 84%, rgba(139, 92, 255, 0.18), transparent 34%),
    linear-gradient(145deg, #03040b 0%, #090d1f 48%, #03040b 100%);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(rgba(255, 255, 255, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.025) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(circle, black 0%, transparent 72%);
}

.shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 28px;
}

.calculator {
  width: min(100%, 520px);
  padding: 38px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background:
    linear-gradient(155deg, rgba(255, 255, 255, 0.08), rgba(255, 255, 255, 0.015)),
    var(--panel);
  box-shadow:
    0 0 0 1px rgba(38, 247, 255, 0.14),
    0 0 22px rgba(38, 247, 255, 0.28),
    0 0 48px rgba(139, 92, 255, 0.2),
    0 0 86px rgba(255, 61, 242, 0.16),
    0 30px 80px rgba(0, 0, 0, 0.72),
    inset 0 0 30px rgba(38, 247, 255, 0.08),
    inset 0 0 80px rgba(255, 61, 242, 0.05);
  backdrop-filter: blur(20px);
}

.eyebrow {
  margin: 0 0 14px;
  color: var(--green);
  font-size: 0.78rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  text-shadow:
    0 0 8px rgba(113, 255, 191, 0.9),
    0 0 22px rgba(113, 255, 191, 0.48),
    0 0 36px rgba(38, 247, 255, 0.26);
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 7vw, 3.65rem);
  line-height: 1.04;
  text-shadow:
    0 0 8px rgba(255, 255, 255, 0.74),
    0 0 18px rgba(38, 247, 255, 0.64),
    0 0 34px rgba(139, 92, 255, 0.54),
    0 0 62px rgba(255, 61, 242, 0.38);
}

.lede {
  margin: 18px 0 28px;
  color: var(--muted);
  line-height: 1.7;
}

.converter {
  display: grid;
  gap: 12px;
}

label {
  color: #cfefff;
  font-size: 0.88rem;
  text-shadow: 0 0 12px rgba(38, 247, 255, 0.42);
}

select,
input,
button {
  width: 100%;
  min-height: 52px;
  border-radius: 8px;
  font: inherit;
}

select,
input {
  border: 1px solid rgba(38, 247, 255, 0.34);
  color: var(--text);
  background: var(--panel-strong);
  padding: 0 16px;
  outline: none;
  font-size: 1.6em;
  box-shadow:
    0 0 0 1px rgba(255, 61, 242, 0.08),
    0 0 18px rgba(38, 247, 255, 0.1),
    inset 0 0 16px rgba(38, 247, 255, 0.06);
}

select:focus,
input:focus {
  border-color: var(--cyan);
  box-shadow:
    0 0 0 1px rgba(38, 247, 255, 0.55),
    0 0 18px rgba(38, 247, 255, 0.38),
    0 0 34px rgba(255, 61, 242, 0.16),
    inset 0 0 18px rgba(38, 247, 255, 0.12);
}

button {
  margin-top: 8px;
  border: 0;
  color: #031019;
  cursor: pointer;
  background: linear-gradient(90deg, var(--cyan), var(--green) 48%, var(--pink));
  box-shadow:
    0 0 12px rgba(38, 247, 255, 0.8),
    0 0 28px rgba(113, 255, 191, 0.42),
    0 0 58px rgba(255, 61, 242, 0.3),
    0 16px 34px rgba(0, 0, 0, 0.48);
  text-shadow: 0 1px 12px rgba(255, 255, 255, 0.64);
  transition: transform 160ms ease, filter 160ms ease;
  display: none;
}

button:hover {
  filter: brightness(1.12) saturate(1.1);
  transform: translateY(-1px);
}

.result-panel {
  margin-top: 28px;
  padding: 24px;
  border: 1px solid rgba(255, 61, 242, 0.28);
  border-radius: 8px;
  background: rgba(5, 8, 20, 0.72);
  text-align: center;
  box-shadow:
    0 0 18px rgba(255, 61, 242, 0.2),
    0 0 36px rgba(38, 247, 255, 0.14),
    inset 0 0 28px rgba(139, 92, 255, 0.12);
}

.result-label {
  display: block;
  color: var(--muted);
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
}

#result {
  display: block;
  margin: 12px 0 8px;
  color: var(--cyan);
  font-size: clamp(2.6rem, 12vw, 5.6rem);
  line-height: 0.95;
  text-shadow:
    0 0 8px rgba(38, 247, 255, 1),
    0 0 22px rgba(38, 247, 255, 0.82),
    0 0 46px rgba(38, 247, 255, 0.48),
    0 0 76px rgba(255, 61, 242, 0.34);
}

#range {
  min-height: 1.5em;
  margin: 0;
  color: #c6d3ef;
  line-height: 1.55;
}

.details {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin: 18px 0 0;
}

.details div {
  padding: 14px;
  border: 1px solid rgba(38, 247, 255, 0.18);
  border-radius: 8px;
  background: rgba(8, 12, 27, 0.7);
  box-shadow: inset 0 0 20px rgba(38, 247, 255, 0.05);
}

dt {
  color: var(--muted);
  font-size: 0.76rem;
  text-transform: uppercase;
}

dd {
  margin: 8px 0 0;
  color: var(--green);
  text-shadow: 0 0 16px rgba(113, 255, 191, 0.45);
}

.note {
  margin: 18px 0 0;
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.65;
}

.is-error {
  color: var(--danger);
  text-shadow: 0 0 18px rgba(255, 122, 168, 0.52);
}

@media (max-width: 560px) {
  .shell {
    padding: 16px;
  }

  .calculator {
    padding: 26px 20px;
  }

  .details {
    grid-template-columns: 1fr;
  }
}