Abstract Class

namespace Delaney
{
    public abstract class LogBase
    {
        protected readonly object lockObj = new object();
        public abstract void Information(string message);
        public abstract void Warning(string message);
        public abstract void Error(string message);
    }
}

Class

using System;
using System.IO;
using System.Threading;

namespace Delaney
{
    public class HTMLLog : LogBase
    {
        bool _errorOpeningFile = false;
        string _fullname = "";
        string _dateFormat = "yyyy-MM-dd HH:mm:ss";

        public HTMLLog(string fullname = "")
        {
            // Guard Clause
            if(string.IsNullOrWhiteSpace(fullname))
            {
                var path = AppDomain.CurrentDomain.BaseDirectory;
                fullname = System.IO.Path.Combine(path, "Log.html");
            }

            _fullname = fullname;

            try
            {
                if (!File.Exists(_fullname))
                    using (var stream = File.CreateText(_fullname))
                    {
                        stream.WriteLine("<style>body { margin-top: 0; }</style>");
                        stream.WriteLine($"<div style=\"position: sticky; top:0px; padding-top:8px; background: white; display:flex; flex-wrap: nowrap; gap: 1rem; font-family: monospace; font-weight:bold;\"><span style=\"white-space: nowrap; padding-right: 5ch\">Date and Time</span><span>Thread Id</span><span style=\"flex: 0 1 auto; padding-right: 6ch;\">Level</span><span>Description</span></div>");
                    }
            }
            catch
            {
                var s = _fullname;
                if (string.IsNullOrWhiteSpace(_fullname))
                    s = "No fullname present";

                Console.WriteLine($"Error creating or loading HTML logger file. Fullname: {s}");
                Console.ReadLine();
                _errorOpeningFile = true;
            }
        }

        public bool IsVerbose { get; set; }
        public override void Information(string message, bool isVerboseLogging = true)
        {
            var colorStyle = "blue";
            var datestring = DateTime.Now.ToString(_dateFormat ) + " ";


            if (!isVerboseLogging)
                return;

            if (_errorOpeningFile)
                return;

            lock (lockObj)
            {
                var threadId = Thread.CurrentThread.ManagedThreadId;
                Console.Write(datestring);
                Console.ForegroundColor = ConsoleColor.Cyan;
                Console.Write("Information");
                Console.ResetColor();
                Console.Write(" " + threadId);
                Console.WriteLine(" " + message);

                if (_errorOpeningFile)
                    return;

                using (var stream = File.AppendText(_fullname))
                {
                    WriteLine(stream, datestring, "Information", message, colorStyle, threadId);
                }
            }
        }

        public override void Warning(string message) 
        {
            var colorStyle = "orange";
            var datestring = DateTime.Now.ToString(_dateFormat) + " ";

            if (_errorOpeningFile)
                return;


            lock (lockObj)
            {
                var threadId = Thread.CurrentThread.ManagedThreadId;
                Console.Write(datestring);
                Console.ForegroundColor = ConsoleColor.DarkYellow;
                Console.Write("Warning    ");
                Console.ResetColor();
                Console.Write(" " + threadId);
                Console.WriteLine(" " + message);

                if (_errorOpeningFile)
                    return;

                using (var stream = File.AppendText(_fullname))
                {
                    WriteLine(stream, datestring, "Warning    ", message, colorStyle, threadId);
                }
            }
        }

        public override void Error(string message)
        {
            var colorStyle = "red";
            var datestring = DateTime.Now.ToString(_dateFormat) + " ";

            if (_errorOpeningFile)
                return;

            lock (lockObj)
            {
                var threadId = Thread.CurrentThread.ManagedThreadId;
                Console.Write(datestring);
                Console.ForegroundColor = ConsoleColor.Red;
                Console.Write("Error      ");
                Console.ResetColor();
                Console.Write(" " + threadId);
                Console.WriteLine(" " + message);

                if (_errorOpeningFile)
                    return;

                using (var stream = File.AppendText(_fullname))
                {
                    WriteLine(stream, datestring, "Error      ", message, colorStyle, threadId);
                }
            }
        }

        private void WriteLine(StreamWriter stream, string dateString, string status, string message, string color, int threadId)
        {
            stream.WriteLine($"<div style=\"display:flex; flex-wrap: nowrap; gap: 1rem; font-family: monospace\"><span style=\"white-space: nowrap;\">{dateString}</span><span style=\"padding-left: 7ch\">{threadId}</span><span style=\"flex: 0 1 auto;color: {color}\">{status}</span><span>{message}</span></div>");
        }
    }
}