Create polished app layout and styling

style.css

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+:root {
+  --bg: #f2f4f8;
+  --panel: #ffffff;
+  --panel-muted: #f8fafc;
+  --text: #10203a;
+  --muted: #5d6b82;
+  --primary: #0f62fe;
+  --primary-hover: #054ada;
+  --border: #d7deea;
+  --canvas-bg: #ffffff;
+  --cell: #2c73ff;
+  --cell-glow: rgba(44, 115, 255, 0.3);
+  --danger: #d92d20;
+  --focus: #7aa3ff;
+  --shadow: 0 10px 30px rgba(16, 32, 58, 0.08);
+}
+
+[data-theme="dark"] {
+  --bg: #0d1420;
+  --panel: #111c2d;
+  --panel-muted: #182538;
+  --text: #e6eefc;
+  --muted: #a8b6ce;
+  --primary: #6aa8ff;
+  --primary-hover: #82b7ff;
+  --border: #24354f;
+  --canvas-bg: #0b1220;
+  --cell: #7fb0ff;
+  --cell-glow: rgba(127, 176, 255, 0.35);
+  --danger: #ff6b6b;
+  --focus: #9fc0ff;
+  --shadow: 0 12px 30px rgba(0, 0, 0, 0.35);
+}
+
+*,
+*::before,
+*::after {
+  box-sizing: border-box;
+}
+
+body {
+  margin: 0;
+  background: radial-gradient(circle at 20% 0%, #dbe8ff33 0%, transparent 35%), var(--bg);
+  color: var(--text);
+  font-family:
+    Inter,
+    system-ui,
+    -apple-system,
+    "Segoe UI",
+    Roboto,
+    "Helvetica Neue",
+    Arial,
+    sans-serif;
+  line-height: 1.5;
+}
+
+.app-header,
+.app-footer {
+  width: min(1280px, 94vw);
+  margin-inline: auto;
+}
+
+.app-header {
+  padding: 1.2rem 0 0.6rem;
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 1rem;
+}
+
+.app-header h1 {
+  margin: 0;
+  font-size: clamp(1.5rem, 2.2vw, 2rem);
+  letter-spacing: -0.02em;
+}
+
+.subtitle {
+  margin: 0.25rem 0 0;
+  color: var(--muted);
+  font-size: 0.95rem;
+}
+
+.app-layout {
+  width: min(1280px, 94vw);
+  margin: 0 auto;
+  display: grid;
+  grid-template-columns: 280px 1fr 320px;
+  gap: 1rem;
+  align-items: start;
+}
+
+.panel {
+  background: var(--panel);
+  border: 1px solid var(--border);
+  border-radius: 14px;
+  box-shadow: var(--shadow);
+  padding: 1rem;
+}
+
+.panel h2 {
+  margin: 0 0 0.75rem;
+  font-size: 1rem;
+  letter-spacing: 0.01em;
+}
+
+.canvas-panel {
+  min-width: 0;
+}
+
+.canvas-header {
+  display: flex;
+  align-items: baseline;
+  justify-content: space-between;
+  gap: 0.75rem;
+}
+
+.canvas-container {
+  background: var(--canvas-bg);
+  border: 1px solid var(--border);
+  border-radius: 12px;
+  overflow: hidden;
+  margin-top: 0.75rem;
+}
+
+#life-canvas {
+  display: block;
+  width: 100%;
+  height: auto;
+  touch-action: none;
+  image-rendering: pixelated;
+  image-rendering: crisp-edges;
+}
+
+.row {
+  display: flex;
+  gap: 0.5rem;
+}
+
+.row.wrap {
+  flex-wrap: wrap;
+}
+
+.field {
+  margin-top: 0.85rem;
+}
+
+.field label {
+  display: block;
+  margin-bottom: 0.35rem;
+  font-size: 0.92rem;
+  color: var(--muted);
+}
+
+input[type="range"],
+select,
+textarea {
+  width: 100%;
+}
+
+button,
+select,
+textarea,
+input {
+  font: inherit;
+}
+
+button {
+  border: 1px solid transparent;
+  background: var(--primary);
+  color: #fff;
+  border-radius: 10px;
+  padding: 0.45rem 0.75rem;
+  cursor: pointer;
+  transition: 140ms ease;
+}
+
+button:hover {
+  background: var(--primary-hover);
+}
+
+button.ghost {
+  background: transparent;
+  color: var(--text);
+  border-color: var(--border);
+}
+
+button.ghost:hover {
+  background: var(--panel-muted);
+}
+
+textarea,
+select,
+input[type="range"] {
+  border: 1px solid var(--border);
+  border-radius: 10px;
+  background: var(--panel-muted);
+  color: var(--text);
+}
+
+textarea {
+  padding: 0.6rem;
+  resize: vertical;
+  min-height: 7rem;
+}
+
+.toggle {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.45rem;
+  color: var(--text);
+  font-size: 0.92rem;
+}
+
+.toggles {
+  margin-top: 0.75rem;
+}
+
+.status-grid {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 0.65rem;
+  margin: 0;
+}
+
+.status-grid div {
+  background: var(--panel-muted);
+  border: 1px solid var(--border);
+  border-radius: 10px;
+  padding: 0.55rem 0.65rem;
+}
+
+.status-grid dt {
+  margin: 0;
+  color: var(--muted);
+  font-size: 0.8rem;
+}
+
+.status-grid dd {
+  margin: 0.15rem 0 0;
+  font-weight: 600;
+}
+
+.muted {
+  margin: 0.6rem 0 0;
+  color: var(--muted);
+  font-size: 0.87rem;
+}
+
+details {
+  background: var(--panel-muted);
+  border: 1px solid var(--border);
+  border-radius: 10px;
+  padding: 0.55rem 0.7rem;
+  margin-bottom: 0.6rem;
+}
+
+summary {
+  cursor: pointer;
+  font-weight: 600;
+}
+
+ol {
+  padding-left: 1.2rem;
+}
+
+.app-footer {
+  padding: 1rem 0 1.5rem;
+  color: var(--muted);
+}
+
+button:focus-visible,
+select:focus-visible,
+textarea:focus-visible,
+input:focus-visible,
+summary:focus-visible {
+  outline: 2px solid var(--focus);
+  outline-offset: 2px;
+}
+
+@media (max-width: 1120px) {
+  .app-layout {
+    grid-template-columns: 1fr;
+  }
+
+  .controls-panel {
+    order: 1;
+  }
+
+  .canvas-panel {
+    order: 2;
+  }
+
+  .side-panel {
+    order: 3;
+  }
+}