* { margin: 0; padding: 0; box-sizing: border-box; }
html, body { width: 100%; height: 100%; overflow: hidden; background: radial-gradient(ellipse at 38% 28%, #0e1828, #05080f 70%); font-family: system-ui, -apple-system, sans-serif; }
canvas { position: fixed; inset: 0; width: 100vw !important; height: 100vh !important; display: block; background: transparent; cursor: default; touch-action: none; }
#back-btn { position: fixed; top: 20px; left: 20px; z-index: 100; display: inline-flex; align-items: center; gap: 7px; padding: 9px 18px 9px 13px; background: rgba(6, 12, 24, 0.72); border: 1px solid rgba(56, 189, 248, 0.22); border-radius: 50px; color: rgba(190, 230, 255, 0.88); font-size: 0.85rem; font-weight: 600; letter-spacing: 0.04em; text-decoration: none; backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px); transition: background 0.25s ease, border-color 0.25s ease, color 0.25s ease; }
#back-btn:hover { background: rgba(14, 30, 58, 0.9); border-color: rgba(56, 189, 248, 0.55); color: #7dd3fc; }
#back-btn svg { flex-shrink: 0; transition: transform 0.25s ease; }
#back-btn:hover svg { transform: translateX(-3px); }