* { box-sizing: border-box; } body { margin: 0; font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; width: 500px; padding: 10px; } code { font-family: source-code-pro, Menlo, Monaco, Consolas, 'Courier New', monospace; }