:root {
  --bg: #050505;
  --text: #f5f5f5;
  --muted: #bebebe;
  --panel: rgba(255, 255, 255, 0.06);
  --panel-border: rgba(255, 255, 255, 0.2);
  --accent: #ffffff;
  --shadow: 0 14px 40px rgba(0, 0, 0, 0.45);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial,
    sans-serif;
}

body {
  display: flex;
  flex-direction: column;
}

.topbar {
  padding: 1rem 1.25rem 0.25rem;
}

.topbar h1 {
  margin: 0;
  letter-spacing: 0.08em;
  font-size: clamp(1.2rem, 2vw, 1.65rem);
  text-transform: uppercase;
  color: var(--accent);
}

.layout {
  flex: 1;
  display: grid;
  grid-template-columns: minmax(240px, 340px) minmax(0, 1fr);
  gap: 1rem;
  padding: 0.75rem 1.25rem 1.25rem;
}

.panel {
  align-self: start;
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 14px;
  box-shadow: var(--shadow);
  padding: 1rem;
  backdrop-filter: blur(4px);
}

.panel h2 {
  margin: 0 0 0.35rem;
  font-size: 1rem;
}

.panel p {
  margin: 0 0 0.85rem;
  color: var(--muted);
  line-height: 1.4;
  font-size: 0.92rem;
}

label {
  display: block;
  margin-bottom: 0.35rem;
  font-size: 0.88rem;
  color: var(--muted);
}

textarea {
  width: 100%;
  border-radius: 10px;
  border: 1px solid var(--panel-border);
  background: rgba(0, 0, 0, 0.45);
  color: var(--text);
  font: inherit;
  line-height: 1.35;
  padding: 0.7rem 0.75rem;
  resize: vertical;
  min-height: 5.4rem;
}

.inline-controls {
  margin-top: 0.85rem;
  display: grid;
  gap: 0.35rem;
  grid-template-columns: auto 1fr auto;
  align-items: center;
}

input[type='range'] {
  width: 100%;
}

#densityLabel {
  min-width: 1.5ch;
  text-align: right;
  color: var(--text);
}

.canvas-shell {
  border-radius: 14px;
  border: 1px solid var(--panel-border);
  box-shadow: var(--shadow);
  background: radial-gradient(circle at 45% 35%, rgba(255, 255, 255, 0.04), transparent 45%);
  min-height: 60vh;
  overflow: hidden;
  position: relative;
}

#particleCanvas {
  display: block;
  width: 100%;
  height: 100%;
}

.noscript-message {
  margin: 1rem 1.25rem;
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 1rem;
  background: var(--panel);
}

@media (max-width: 900px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .panel {
    order: 2;
  }

  .canvas-shell {
    min-height: 52vh;
  }
}

@media (prefers-reduced-motion: reduce) {
  .panel,
  .canvas-shell {
    transition: none;
  }
}