function wrapTextLinesInSpan(element){
    const lines = element.textContent.split('\n').filter(Boolean);
    element.textContent = '';

    for (let index = 0; index < lines.length; index++) {
        const span = document.createElement('span');
        span.className = 'line';
        span.textContent = lines[index];
        element.appendChild(span);
        
        if(index < lines.length - 1){
            element.appendChild(document.createTextNode('\n'));
        }
    }
}

document.querySelectorAll('pre.number-lines').forEach(wrapTextLinesInSpan);