body { margin: 0; font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif; } .app { width: 100vw; height: 100vh; display: flex; justify-content: center; align-items: center; .border { border: 1px solid #e0e0e0; } }