/* ─────────────────────────────────────────────────────────────────────────
   Abstract Galaxy — CSS-only motion theme for the unit-converter demo.
   ───────────────────────────────────────────────────────────────────────── */

:root {
  --space-0: #04020c;
  --space-1: #0c0b22;
  --space-2: #160f32;
  --indigo: #5b6bff;
  --violet: #8b5cf6;
  --magenta: #d946ef;
  --cyan: #67e8f9;
  --gold: #f4d35e;
  --text: #e8e8f0;
  --text-dim: #9aa0c0;
  --text-mute: #6e7396;
  --error: #ff7a8a;
  --ok: #6ee7b7;
  --card-bg: rgba(20, 18, 48, 0.45);
  --card-border: rgba(180, 170, 255, 0.18);
  --radius-lg: 24px;
  --radius-md: 14px;
  --shadow-card: 0 30px 60px -20px rgba(0, 0, 0, 0.6), 0 0 0 1px var(--card-border) inset;
  --font-sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial,
    sans-serif;
  --font-mono: ui-monospace, "JetBrains Mono", "Fira Code", SFMono-Regular, Menlo, Consolas,
    monospace;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: var(--space-0);
  color: var(--text);
  font-family: var(--font-sans);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100%;
}

body {
  position: relative;
  overflow-x: hidden;
  padding: clamp(2rem, 5vw, 5rem) clamp(1rem, 4vw, 3rem) 4rem;
  isolation: isolate;
}

/* ─────────── Galaxy backdrop ─────────── */

.galaxy {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background: radial-gradient(
      circle at 50% 120%,
      var(--space-2) 0%,
      var(--space-1) 30%,
      var(--space-0) 70%
    ), var(--space-0);
}

.nebula {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  mix-blend-mode: screen;
  opacity: 0.55;
  will-change: transform;
}

.nebula-a {
  width: 70vw;
  height: 70vw;
  left: -20vw;
  top: -25vw;
  background: radial-gradient(
    circle,
    rgba(91, 107, 255, 0.55) 0%,
    rgba(139, 92, 246, 0.25) 40%,
    transparent 70%
  );
  animation: drift-a 90s linear infinite;
}

.nebula-b {
  width: 60vw;
  height: 60vw;
  right: -15vw;
  bottom: -20vw;
  background: radial-gradient(
    circle,
    rgba(217, 70, 239, 0.45) 0%,
    rgba(244, 114, 182, 0.18) 45%,
    transparent 75%
  );
  animation: drift-b 120s linear infinite reverse;
}

@keyframes drift-a {
  from {
    transform: translate3d(0, 0, 0) rotate(0deg);
  }
  to {
    transform: translate3d(4vw, -2vw, 0) rotate(360deg);
  }
}

@keyframes drift-b {
  from {
    transform: translate3d(0, 0, 0) rotate(0deg);
  }
  to {
    transform: translate3d(-3vw, 3vw, 0) rotate(360deg);
  }
}

/* Star fields via box-shadow trick — no JS, no canvas. */
.stars {
  position: absolute;
  inset: 0;
  background: transparent;
}

.stars::after {
  content: "";
  position: absolute;
  width: 1px;
  height: 1px;
  background: transparent;
  border-radius: 50%;
}

.stars-far::after {
  box-shadow:
    14vw 8vh 0 #b0b8ff, 33vw 22vh 0 #ffffff, 71vw 5vh 0 #c5cdff,
    88vw 18vh 0 #ffffff, 9vw 34vh 0 #dcdcff, 25vw 41vh 0 #ffffff,
    47vw 36vh 0 #b8c4ff, 60vw 50vh 0 #ffffff, 82vw 39vh 0 #d0d8ff,
    96vw 55vh 0 #ffffff, 4vw 60vh 0 #ffffff, 18vw 73vh 0 #c0c8ff,
    37vw 79vh 0 #ffffff, 55vw 67vh 0 #d4daff, 78vw 81vh 0 #ffffff,
    91vw 92vh 0 #b8c4ff, 12vw 89vh 0 #ffffff, 28vw 96vh 0 #ccd2ff,
    45vw 88vh 0 #ffffff, 65vw 95vh 0 #ffffff, 73vw 11vh 0 #ffffff,
    52vw 17vh 0 #cdd3ff, 40vw 60vh 0 #ffffff, 67vw 75vh 0 #b5bff5;
  animation: twinkle 6s ease-in-out infinite alternate;
}

.stars-near::after {
  box-shadow:
    22vw 12vh 0 1px #ffffff, 48vw 28vh 0 1px #fefefe, 81vw 13vh 0 1px #ffffff,
    7vw 48vh 0 1px #ffffff, 35vw 52vh 0 1px #fefefe, 62vw 44vh 0 1px #ffffff,
    93vw 30vh 0 1px #ffffff, 15vw 67vh 0 1px #fefefe, 43vw 72vh 0 1px #ffffff,
    74vw 65vh 0 1px #ffffff, 89vw 78vh 0 1px #fefefe, 3vw 85vh 0 1px #ffffff,
    30vw 94vh 0 1px #ffffff, 58vw 84vh 0 1px #fefefe, 70vw 90vh 0 1px #ffffff;
  animation: twinkle 4s ease-in-out infinite alternate;
}

@keyframes twinkle {
  0% {
    opacity: 0.55;
  }
  100% {
    opacity: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  .nebula,
  .stars::after {
    animation: none !important;
  }
}

/* ─────────── Hero ─────────── */

.hero {
  max-width: 880px;
  margin: 0 auto 3rem;
  text-align: center;
}

.eyebrow {
  font-size: 0.78rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-mute);
  margin: 0 0 1rem;
}

.hero h1 {
  font-size: clamp(2.6rem, 6vw, 4.4rem);
  font-weight: 300;
  letter-spacing: -0.02em;
  margin: 0 0 1rem;
  line-height: 1;
}

.title-grad {
  background: linear-gradient(
    120deg,
    var(--cyan) 0%,
    var(--indigo) 35%,
    var(--violet) 65%,
    var(--magenta) 100%
  );
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  filter: drop-shadow(0 4px 30px rgba(139, 92, 246, 0.35));
}

.tagline {
  color: var(--text-dim);
  font-size: 1.05rem;
  line-height: 1.6;
  max-width: 36rem;
  margin: 0 auto 1.5rem;
}

.install {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.92rem;
  padding: 0.55rem 1rem;
  border-radius: 999px;
  background: rgba(20, 18, 48, 0.6);
  border: 1px solid var(--card-border);
  color: var(--text);
  backdrop-filter: blur(10px);
}

.install .prompt {
  color: var(--cyan);
  margin-right: 0.45rem;
}

/* ─────────── Card primitives ─────────── */

main {
  max-width: 880px;
  margin: 0 auto;
  display: grid;
  gap: 1.75rem;
}

.card {
  position: relative;
  background: var(--card-bg);
  backdrop-filter: blur(24px) saturate(1.2);
  -webkit-backdrop-filter: blur(24px) saturate(1.2);
  border-radius: var(--radius-lg);
  padding: clamp(1.4rem, 3vw, 2.2rem);
  box-shadow: var(--shadow-card);
  overflow: hidden;
}

.card-glow {
  position: absolute;
  inset: -1px;
  border-radius: inherit;
  background: linear-gradient(
    135deg,
    rgba(91, 107, 255, 0.5),
    rgba(139, 92, 246, 0.2),
    rgba(217, 70, 239, 0.45)
  );
  pointer-events: none;
  z-index: -1;
  filter: blur(20px);
  opacity: 0.4;
}

.card-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.card-head h2 {
  font-size: 1.25rem;
  font-weight: 500;
  margin: 0;
  letter-spacing: -0.01em;
}

.badge {
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-mute);
  border: 1px solid var(--card-border);
  padding: 0.3rem 0.65rem;
  border-radius: 999px;
}

.muted {
  color: var(--text-dim);
  font-size: 0.92rem;
  line-height: 1.6;
  margin: 0 0 1rem;
}

.muted code,
code:not(.install) {
  font-family: var(--font-mono);
  background: rgba(255, 255, 255, 0.06);
  padding: 0.1rem 0.4rem;
  border-radius: 6px;
  font-size: 0.86em;
  color: var(--cyan);
}

/* ─────────── Playground ─────────── */

.grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem 1rem;
  margin-bottom: 1.5rem;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  min-width: 0;
}

.field-category,
.field-value {
  grid-column: span 2;
}

.field-arrow {
  display: none;
}

@media (min-width: 640px) {
  .grid {
    grid-template-columns: 1fr 0.2fr 1fr;
  }
  .field-category {
    grid-column: 1 / -1;
  }
  .field-value {
    grid-column: 1 / -1;
  }
  .field-from {
    grid-column: 1;
  }
  .field-arrow {
    display: flex;
    align-items: end;
    justify-content: center;
    color: var(--text-mute);
    font-size: 1.6rem;
    padding-bottom: 0.6rem;
  }
  .field-to {
    grid-column: 3;
  }
}

.field label {
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-mute);
}

.field input,
.field select {
  font-family: inherit;
  font-size: 1rem;
  color: var(--text);
  background: rgba(0, 0, 0, 0.35);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 0.75rem 0.9rem;
  outline: none;
  transition: border-color 150ms ease, box-shadow 150ms ease;
  width: 100%;
  appearance: none;
}

.field select {
  background-image: linear-gradient(45deg, transparent 50%, var(--text-dim) 50%),
    linear-gradient(135deg, var(--text-dim) 50%, transparent 50%);
  background-position: calc(100% - 18px) 50%, calc(100% - 12px) 50%;
  background-size: 6px 6px, 6px 6px;
  background-repeat: no-repeat;
  padding-right: 2rem;
}

.field input:focus,
.field select:focus {
  border-color: var(--indigo);
  box-shadow: 0 0 0 4px rgba(91, 107, 255, 0.2), 0 0 30px rgba(91, 107, 255, 0.3);
}

.field select option {
  background: var(--space-1);
  color: var(--text);
}

/* Toggle */
.toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  cursor: pointer;
  user-select: none;
  font-size: 0.85rem;
  color: var(--text-dim);
}

.toggle input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.toggle-slot {
  position: relative;
  width: 38px;
  height: 22px;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid var(--card-border);
  border-radius: 999px;
  transition: background 200ms ease;
}

.toggle-knob {
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  background: var(--text-dim);
  border-radius: 50%;
  transition: transform 200ms ease, background 200ms ease;
}

.toggle input:checked + .toggle-slot {
  background: linear-gradient(135deg, var(--indigo), var(--violet));
}

.toggle input:checked + .toggle-slot .toggle-knob {
  transform: translateX(16px);
  background: #fff;
}

.toggle input:focus-visible + .toggle-slot {
  box-shadow: 0 0 0 3px rgba(91, 107, 255, 0.35);
}

/* Result */
.result {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.4rem;
  padding: 1.6rem 1rem;
  background: linear-gradient(180deg, rgba(91, 107, 255, 0.08), rgba(217, 70, 239, 0.04));
  border-radius: var(--radius-md);
  border: 1px dashed var(--card-border);
  text-align: center;
}

.result-number {
  font-family: var(--font-mono);
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  font-weight: 500;
  letter-spacing: -0.02em;
  color: #fff;
  text-shadow: 0 0 30px rgba(139, 92, 246, 0.5), 0 0 60px rgba(91, 107, 255, 0.25);
  word-break: break-all;
}

.result-unit {
  font-size: 1.05rem;
  color: var(--cyan);
  letter-spacing: 0.02em;
}

.result-meta {
  font-size: 0.8rem;
  color: var(--text-mute);
  font-family: var(--font-mono);
}

.result.is-error .result-number {
  color: var(--error);
  text-shadow: 0 0 30px rgba(255, 122, 138, 0.4);
  font-size: 1.05rem;
}

/* ─────────── BigInt presets ─────────── */

.presets {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.75rem;
}

.preset {
  background: rgba(0, 0, 0, 0.3);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 0.9rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  cursor: pointer;
  text-align: left;
  color: var(--text);
  font: inherit;
  transition: border-color 150ms ease, transform 150ms ease, box-shadow 150ms ease;
}

.preset:hover {
  border-color: var(--indigo);
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(91, 107, 255, 0.15);
}

.preset .preset-call {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--text-dim);
}

.preset .preset-out {
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--gold);
  word-break: break-all;
}

.preset.is-error .preset-out {
  color: var(--error);
  font-size: 0.85rem;
}

/* ─────────── Errors panel ─────────── */

.error-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-bottom: 1rem;
}

.error-buttons button {
  background: rgba(255, 122, 138, 0.08);
  border: 1px solid rgba(255, 122, 138, 0.3);
  color: #ffb0b8;
  padding: 0.55rem 0.95rem;
  border-radius: 999px;
  font: inherit;
  font-size: 0.85rem;
  cursor: pointer;
  transition: background 150ms ease, transform 150ms ease;
}

.error-buttons button:hover {
  background: rgba(255, 122, 138, 0.18);
  transform: translateY(-1px);
}

.error-buttons button:focus-visible {
  outline: 2px solid var(--error);
  outline-offset: 2px;
}

.error-output {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.6;
  color: var(--text-dim);
  background: rgba(0, 0, 0, 0.4);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 1rem 1.1rem;
  margin: 0;
  white-space: pre-wrap;
  word-break: break-word;
}

/* ─────────── Footer ─────────── */

footer {
  margin: 4rem auto 0;
  max-width: 880px;
  text-align: center;
  color: var(--text-mute);
  font-size: 0.86rem;
}

footer .link {
  color: var(--text-dim);
  text-decoration: none;
  border-bottom: 1px dashed transparent;
  transition: color 150ms ease, border-color 150ms ease;
}

footer .link:hover {
  color: var(--cyan);
  border-bottom-color: currentColor;
}

footer .dot {
  margin: 0 0.5rem;
  opacity: 0.5;
}