// @nuget: HtmlAgilityPack

using System;

using HtmlAgilityPack;

using System.Linq;

public class Program

{

    public static void Main()

    {

        WithBoldText();

        WithoutBoldText();

    }

    private static void WithBoldText()

    {

        var html = @"

<div class=""Post"">

    <img src=""image.png"" alt=""Alt Text"">

    <br>

    <b>THIS TEXT IS WHAT I WANT</b>

    <div class=""DesktopElements"">

        <br>

        Hello world

    </div>

    <br>

    Some text here.

    <br>

    <b>Title</b>

    <br>

    Some more text here.

</div>";

        var doc = new HtmlDocument();

        doc.LoadHtml(html);

        var node = doc.DocumentNode.SelectSingleNode(".//div[@class='Post']")

            .Descendants()

            .TakeWhile(node => !node.HasClass("DesktopElements"))

            .FirstOrDefault(node => node.Name == "b");

        Console.WriteLine("WithBoldText: " + (node?.InnerText ?? "none"));

    }

    private static void WithoutBoldText()

    {

        var html = @"

<div class=""Post"">

    <img src=""image.png"" alt=""Alt Text"">

    <br>

    <div class=""DesktopElements"">

        <br>

        Hello world

    </div>

    <br>

    Some text here.

    <br>

    <b>Title</b>

    <br>

    Some more text here.

</div>";

        var doc = new HtmlDocument();

        doc.LoadHtml(html);

        var node = doc.DocumentNode.SelectSingleNode(".//div[@class='Post']")

            .Descendants()

            .TakeWhile(node => !node.HasClass("DesktopElements"))

            .FirstOrDefault(node => node.Name == "b");

        Console.WriteLine("WithoutBoldText: " + (node?.InnerText ?? "none"));

    }

}