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; } code { font-family: source-code-pro, Menlo, Monaco, Consolas, 'Courier New', monospace; } .css-serial { counter-reset: serial-number; /* Set the serial number counter to 0 */ } .css-serial td:first-child:before { counter-increment: serial-number; /* Increment the serial number counter */ content: counter(serial-number); /* Display the counter */ }