spectre.console/src/Spectre.Console/Rendering/Borders/Tables/HeavyHeadTableBorder.cs

using System;

namespace Spectre.Console.Rendering
{
    /// <summary>
    /// Represents a border with a heavy header.
    /// </summary>
    public sealed class HeavyHeadTableBorder : TableBorder
    {
        /// <inheritdoc/>
        public override TableBorder? SafeBorder => TableBorder.Square;

        /// <inheritdoc/>
        protected override string GetBorderPart(TableBorderPart part)
        {
            return part switch
            {
                TableBorderPart.HeaderTopLeft => "┏",
                TableBorderPart.HeaderTop => "━",
                TableBorderPart.HeaderTopSeparator => "┳",
                TableBorderPart.HeaderTopRight => "┓",
                TableBorderPart.HeaderLeft => "┃",
                TableBorderPart.HeaderSeparator => "┃",
                TableBorderPart.HeaderRight => "┃",
                TableBorderPart.HeaderBottomLeft => "┡",
                TableBorderPart.HeaderBottom => "━",
                TableBorderPart.HeaderBottomSeparator => "╇",
                TableBorderPart.HeaderBottomRight => "┩",
                TableBorderPart.CellLeft => "│",
                TableBorderPart.CellSeparator => "│",
                TableBorderPart.CellRight => "│",
                TableBorderPart.FooterBottomLeft => "└",
                TableBorderPart.FooterBottom => "─",
                TableBorderPart.FooterBottomSeparator => "┴",
                TableBorderPart.FooterBottomRight => "┘",
                _ => throw new InvalidOperationException("Unknown border part."),
            };
        }
    }
}