/* Day 18 — Gravitational N-Body Simulation */

:root {
  color-scheme: dark;
  --bg: #050816;
  --panel: rgba(8, 12, 24, 0.58);
  --panel-strong: rgba(10, 16, 30, 0.78);
  --panel-border: rgba(150, 175, 255, 0.16);
  --text: #f5f7ff;
  --text-soft: rgba(223, 230, 255, 0.72);
  --accent: #8fd8ff;
  --accent-warm: #ffd36a;
  --accent-danger: #ff8a75;
  --shadow: 0 30px 80px rgba(0, 0, 0, 0.42);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  height: 100%;
}

body {
  background:
    radial-gradient(circle at 18% 18%, rgba(83, 155, 255, 0.12), transparent 26%),
    radial-gradient(circle at 82% 14%, rgba(255, 178, 102, 0.08), transparent 24%),
    linear-gradient(160deg, #030612 0%, #050816 42%, #040a18 100%);
  color: var(--text);
  font-family: "Space Grotesk", "Segoe UI", sans-serif;
  overflow: hidden;
}

.app-shell::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at center, rgba(255, 255, 255, 0.04), transparent 42%),
    linear-gradient(rgba(255, 255, 255, 0.015) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.015) 1px, transparent 1px);
  background-size: auto, 4.5rem 4.5rem, 4.5rem 4.5rem;
  mask-image: radial-gradient(circle at center, black 35%, transparent 100%);
  opacity: 0.35;
  pointer-events: none;
}

.app-shell {
  position: relative;
  width: 100%;
  height: 100vh;
  height: 100svh;
}

#gravity-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
  cursor: crosshair;
  touch-action: none;
}

.hero-panel,
.control-dock,
.status-bar,
.no-script {
  position: absolute;
  z-index: 2;
}

.hero-panel {
  top: 1.25rem;
  left: 1.25rem;
  width: min(28rem, calc(100vw - 2.5rem));
  padding: 1.25rem 1.35rem 1.35rem;
  background: linear-gradient(180deg, rgba(11, 18, 34, 0.76), rgba(7, 12, 24, 0.56));
  border: 1px solid var(--panel-border);
  border-radius: 1.5rem;
  backdrop-filter: blur(20px) saturate(1.2);
  -webkit-backdrop-filter: blur(20px) saturate(1.2);
  box-shadow: var(--shadow);
}

.control-dock {
  top: 1.25rem;
  right: 1.25rem;
  width: min(24rem, calc(100vw - 2.5rem));
  display: grid;
  gap: 1rem;
  padding: 1.15rem 1.2rem;
  background: linear-gradient(180deg, rgba(10, 16, 30, 0.82), rgba(7, 12, 24, 0.68));
  border: 1px solid var(--panel-border);
  border-radius: 1.4rem;
  backdrop-filter: blur(22px) saturate(1.4);
  -webkit-backdrop-filter: blur(22px) saturate(1.4);
  box-shadow: var(--shadow);
}

.status-bar {
  left: 1.25rem;
  right: 1.25rem;
  bottom: 1.25rem;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem 1.15rem;
  background: linear-gradient(180deg, rgba(9, 15, 28, 0.74), rgba(7, 11, 22, 0.52));
  border: 1px solid rgba(150, 175, 255, 0.12);
  border-radius: 1.25rem;
  backdrop-filter: blur(20px) saturate(1.2);
  -webkit-backdrop-filter: blur(20px) saturate(1.2);
}

.hero-panel__eyebrow,
.control-labels label,
.toggle span,
.action-row button,
.status-metrics span {
  font-family: "Azeret Mono", monospace;
}

.hero-panel__eyebrow {
  margin-bottom: 0.7rem;
  color: var(--accent);
  font-size: 0.72rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}

.hero-panel h1 {
  font-size: clamp(2rem, 4vw, 3.4rem);
  line-height: 0.95;
  letter-spacing: -0.05em;
  max-width: 10ch;
}

.hero-panel__lede {
  margin-top: 0.9rem;
  max-width: 34ch;
  color: var(--text-soft);
  font-size: 0.98rem;
  line-height: 1.6;
}

.hero-panel h1,
.hero-panel__lede,
.control-labels,
.status-copy,
.status-metrics {
  margin: 0;
}

.control-group,
.toggle-row,
.action-row {
  display: grid;
  gap: 0.75rem;
}

.control-group {
  gap: 0.85rem;
}

.control-labels,
.toggle-row,
.action-row,
.status-metrics {
  display: flex;
  align-items: center;
}

.control-labels,
.status-bar,
.status-metrics {
  justify-content: space-between;
}

.control-labels label,
.control-labels output {
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.control-labels label {
  color: var(--text-soft);
}

.control-labels output {
  color: var(--accent-warm);
}

.toggle-row,
.action-row,
.status-metrics {
  gap: 0.75rem;
  flex-wrap: wrap;
}

.toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.7rem 0.85rem;
  border: 1px solid rgba(150, 175, 255, 0.14);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-soft);
}

.toggle input {
  accent-color: var(--accent);
}

.toggle span {
  font-size: 0.66rem;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.action-row button {
  padding: 0.78rem 0.95rem;
  border: 1px solid rgba(150, 175, 255, 0.14);
  border-radius: 999px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.08), rgba(255, 255, 255, 0.02)),
    rgba(255, 255, 255, 0.02);
  color: var(--text);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  cursor: pointer;
  transition:
    transform 180ms ease,
    border-color 180ms ease,
    background 180ms ease,
    box-shadow 180ms ease;
}

.action-row button:hover {
  transform: translateY(-1px);
  border-color: rgba(143, 216, 255, 0.34);
  box-shadow: 0 18px 32px rgba(0, 0, 0, 0.2);
}

.action-row button:active {
  transform: translateY(0);
}

input[type="range"] {
  width: 100%;
  margin: 0;
  accent-color: var(--accent);
}

input[type="range"]::-webkit-slider-runnable-track {
  height: 0.45rem;
  border-radius: 999px;
  background: linear-gradient(90deg, rgba(126, 216, 255, 0.34), rgba(255, 211, 106, 0.3));
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 1rem;
  height: 1rem;
  margin-top: -0.28rem;
  border: 2px solid rgba(5, 8, 22, 0.8);
  border-radius: 50%;
  background: #f5f7ff;
  box-shadow: 0 0 0 5px rgba(143, 216, 255, 0.14);
}

input[type="range"]::-moz-range-track {
  height: 0.45rem;
  border: 0;
  border-radius: 999px;
  background: linear-gradient(90deg, rgba(126, 216, 255, 0.34), rgba(255, 211, 106, 0.3));
}

input[type="range"]::-moz-range-thumb {
  width: 1rem;
  height: 1rem;
  border: 2px solid rgba(5, 8, 22, 0.8);
  border-radius: 50%;
  background: #f5f7ff;
  box-shadow: 0 0 0 5px rgba(143, 216, 255, 0.14);
}

.status-copy {
  max-width: 40rem;
  color: var(--text-soft);
  line-height: 1.5;
  font-size: 0.94rem;
}

.status-metrics span {
  padding: 0.6rem 0.78rem;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(150, 175, 255, 0.12);
  color: var(--accent);
  font-size: 0.68rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.no-script {
  padding: 0.8rem 1rem;
  border-radius: 0.95rem;
  background: var(--panel-strong);
  border: 1px solid rgba(255, 138, 117, 0.2);
  color: var(--accent-danger);
  box-shadow: var(--shadow);
}

.control-dock::before,
.hero-panel::before {
  content: "";
  position: absolute;
  inset: 1px;
  border-radius: inherit;
  border: 1px solid rgba(255, 255, 255, 0.05);
  pointer-events: none;
}

.no-script {
  left: 1.25rem;
  bottom: 6.5rem;
}

@media (max-width: 960px) {
  .hero-panel,
  .control-dock,
  .status-bar,
  .no-script {
    left: 0.9rem;
    right: 0.9rem;
    width: auto;
  }

  .hero-panel {
    top: 0.9rem;
  }

  .hero-panel h1 {
    font-size: clamp(1.9rem, 8vw, 2.8rem);
    max-width: 12ch;
  }

  .control-dock {
    top: auto;
    bottom: 7.9rem;
  }

  .status-bar {
    bottom: 0.9rem;
    flex-direction: column;
    align-items: flex-start;
  }

  .status-copy {
    max-width: none;
  }

  .status-metrics {
    width: 100%;
  }
}

@media (max-width: 640px) {
  .hero-panel,
  .control-dock,
  .status-bar {
    padding-left: 1rem;
    padding-right: 1rem;
  }

  .hero-panel__lede {
    font-size: 0.9rem;
  }

  .control-dock {
    bottom: 12.5rem;
  }

  .status-bar {
    padding-top: 0.85rem;
    padding-bottom: 0.85rem;
    gap: 0.65rem;
  }

  .toggle-row,
  .action-row {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .toggle,
  .action-row button {
    justify-content: center;
    width: 100%;
  }

  .status-copy {
    font-size: 0.84rem;
    line-height: 1.45;
  }

  .status-metrics {
    gap: 0.55rem;
  }

  .status-metrics span {
    flex: 1 1 10rem;
    justify-content: center;
    text-align: center;
  }

  .no-script {
    bottom: 14rem;
  }
}