* { margin: 0; padding: 0; box-sizing: border-box; }
html, body { width: 100%; height: 100%; overflow: hidden; background: #fff; font-family: system-ui, sans-serif; }
#viewer-iframe { width: 100%; height: 100%; border: none; }
#loading { display: flex; align-items: center; justify-content: center; height: 100%; color: #888; font-size: 16px; }
#error { display: none; align-items: center; justify-content: center; height: 100%; color: #c0392b; font-size: 16px; text-align: center; padding: 20px; }