html, body { margin: 0; background: #525659; }
#loading { color: #fff; font-family: system-ui, sans-serif; text-align: center; padding: 40px 16px; font-size: 16px; }
#viewer { max-width: 900px; margin: 0 auto; padding: 16px 0; }
#viewer canvas { display: block; width: 100%; height: auto; margin: 0 auto 8px; box-shadow: 0 2px 8px rgba(0, 0, 0, 0.4); }