A Railscasts-Renewed theme for Zed, imported from https://github.com/PaulOlteanu/Railscasts-Renewed, used a bit One Dark to fix empty fields, tweak a bit to actually match VSCode colors

Railscasts-Renewed.json

{
  "$schema": "https://zed.dev/schema/themes/v0.1.0.json",
  "name": "Railscasts Renewed",
  "author": "Utensil Song",
  "themes": [
    {
      "name": "Railscasts Renewed Dark",
      "appearance": "dark",
      "style": {
        "background.appearance": "opaque",
        "border": "#464b57ff",
        "border.variant": "#363c46ff",
        "border.focused": "#293b5bff",
        "border.selected": "#293b5bff",
        "border.transparent": "#00000000",
        "border.disabled": "#414754ff",
        "elevated_surface.background": "#2f343eff",
        "surface.background": "#2f343eff",
        "background": "#262626",
        "element.background": "#2e343eff",
        "element.hover": "#363c46ff",
        "element.active": "#454a56ff",
        "element.selected": "#454a56ff",
        "element.disabled": "#2e343eff",
        "drop_target.background": "#83899480",
        "ghost_element.background": "#00000000",
        "ghost_element.hover": "#363c46ff",
        "ghost_element.active": "#454a56ff",
        "ghost_element.selected": "#454a56ff",
        "ghost_element.disabled": "#2e343eff",
        "text": "#c8ccd4ff",
        "text.muted": "#838994ff",
        "text.placeholder": "#696B77ff",
        "text.disabled": "#696B77ff",
        "text.accent": "#74ade8ff",
        "icon": "#c8ccd4ff",
        "icon.muted": "#838994ff",
        "icon.disabled": "#696B77ff",
        "icon.placeholder": "#838994ff",
        "icon.accent": "#74ade8ff",
        "status_bar.background": "#2d2d2d",
        "title_bar.background": "#2d2d2d",
        "title_bar.inactive_background": "#2e343eff",
        "toolbar.background": "#2d2d2d",
        "tab_bar.background": "#2d2d2d",
        "tab.inactive_background": "#2f343eff",
        "tab.active_background": "#282c33ff",
        "search.match_background": "#74ade866",
        "panel.background": "#212122",
        "panel.focused_border": null,
        "pane.focused_border": null,
        "scrollbar.thumb.background": "#c8ccd44c",
        "scrollbar.thumb.hover_background": "#363c46ff",
        "scrollbar.thumb.border": "#363c46ff",
        "scrollbar.track.background": "#00000000",
        "scrollbar.track.border": "#2e333cff",
        "editor.foreground": "#E6E1DC",
        "editor.background": "#262626",
        "editor.gutter.background": "#262626",
        "editor.subheader.background": "#2f343eff",
        "editor.active_line.background": "#333435",
        "editor.highlighted_line.background": "#2f343eff",
        "editor.line_number": "#c8ccd459",
        "editor.active_line_number": "#E6E1DC",
        "editor.invisible": "#696B77ff",
        "editor.wrap_guide": "#c8ccd40d",
        "editor.active_wrap_guide": "#c8ccd41a",
        "editor.document_highlight.read_background": "#74ade81a",
        "editor.document_highlight.write_background": "#555a6366",
        "terminal.background": "#262626",
        "terminal.foreground": "#c8ccd4ff",
        "terminal.bright_foreground": "#c8ccd4ff",
        "terminal.dim_foreground": "#282c33ff",
        "terminal.ansi.black": "#282c33ff",
        "terminal.ansi.bright_black": "#525561ff",
        "terminal.ansi.dim_black": "#c8ccd4ff",
        "terminal.ansi.red": "#d07277ff",
        "terminal.ansi.bright_red": "#673a3cff",
        "terminal.ansi.dim_red": "#eab7b9ff",
        "terminal.ansi.green": "#a1c181ff",
        "terminal.ansi.bright_green": "#4d6140ff",
        "terminal.ansi.dim_green": "#d1e0bfff",
        "terminal.ansi.yellow": "#dec184ff",
        "terminal.ansi.bright_yellow": "#786441ff",
        "terminal.ansi.dim_yellow": "#f1dfc1ff",
        "terminal.ansi.blue": "#74ade8ff",
        "terminal.ansi.bright_blue": "#385378ff",
        "terminal.ansi.dim_blue": "#bed5f4ff",
        "terminal.ansi.magenta": "#be5046ff",
        "terminal.ansi.bright_magenta": "#5e2b26ff",
        "terminal.ansi.dim_magenta": "#e6a79eff",
        "terminal.ansi.cyan": "#6eb4bfff",
        "terminal.ansi.bright_cyan": "#3a565bff",
        "terminal.ansi.dim_cyan": "#b9d9dfff",
        "terminal.ansi.white": "#c8ccd4ff",
        "terminal.ansi.bright_white": "#c8ccd4ff",
        "terminal.ansi.dim_white": "#575d65ff",
        "link_text.hover": "#74ade8ff",
        "conflict": "#dec184ff",
        "conflict.background": "#dec1841a",
        "conflict.border": "#5d4c2fff",
        "created": "#a1c181ff",
        "created.background": "#a1c1811a",
        "created.border": "#38482fff",
        "deleted": "#d07277ff",
        "deleted.background": "#d072771a",
        "deleted.border": "#4c2b2cff",
        "error": "#d07277ff",
        "error.background": "#d072771a",
        "error.border": "#4c2b2cff",
        "hidden": "#696B77ff",
        "hidden.background": "#696B771a",
        "hidden.border": "#414754ff",
        "hint": "#969696ff",
        "hint.background": "#5a6f891a",
        "hint.border": "#293b5bff",
        "ignored": "#696B77ff",
        "ignored.background": "#696B771a",
        "ignored.border": "#464b57ff",
        "info": "#74ade8ff",
        "info.background": "#74ade81a",
        "info.border": "#293b5bff",
        "modified": "#dec184ff",
        "modified.background": "#dec1841a",
        "modified.border": "#5d4c2fff",
        "predictive": "#5a6a87ff",
        "predictive.background": "#5a6a871a",
        "predictive.border": "#38482fff",
        "renamed": "#74ade8ff",
        "renamed.background": "#74ade81a",
        "renamed.border": "#293b5bff",
        "success": "#a1c181ff",
        "success.background": "#a1c1811a",
        "success.border": "#38482fff",
        "unreachable": "#838994ff",
        "unreachable.background": "#8389941a",
        "unreachable.border": "#464b57ff",
        "warning": "#dec184ff",
        "warning.background": "#dec1841a",
        "warning.border": "#5d4c2fff",
        "players": [
          {
            "cursor": "#74ade8ff",
            "background": "#74ade8ff",
            "selection": "#74ade83d"
          },
          {
            "cursor": "#be5046ff",
            "background": "#be5046ff",
            "selection": "#be50463d"
          },
          {
            "cursor": "#bf956aff",
            "background": "#bf956aff",
            "selection": "#bf956a3d"
          },
          {
            "cursor": "#b477cfff",
            "background": "#b477cfff",
            "selection": "#b477cf3d"
          },
          {
            "cursor": "#6eb4bfff",
            "background": "#6eb4bfff",
            "selection": "#6eb4bf3d"
          },
          {
            "cursor": "#d07277ff",
            "background": "#d07277ff",
            "selection": "#d072773d"
          },
          {
            "cursor": "#dec184ff",
            "background": "#dec184ff",
            "selection": "#dec1843d"
          },
          {
            "cursor": "#a1c181ff",
            "background": "#a1c181ff",
            "selection": "#a1c1813d"
          }
        ],
        "syntax": {
          "attribute": {
            "color": "#FFC66D",
            "font_style": null,
            "font_weight": null
          },
          "comment": {
            "color": "#BC9458",
            "font_style": null,
            "font_weight": null
          },
          "comment.doc": {
            "color": "#BC9458",
            "font_style": null,
            "font_weight": null
          },
          "constant": {
            "color": "#FFC66D",
            "font_style": null,
            "font_weight": null
          },
          "constructor": {
            "color": "#DA4939",
            "font_style": null,
            "font_weight": null
          },
          "function": {
            "color": "#6D9CBE",
            "font_style": null,
            "font_weight": null
          },
          "keyword": {
            "color": "#CC7833",
            "font_style": null,
            "font_weight": null
          },
          "number": {
            "color": "#FFC66D",
            "font_style": null,
            "font_weight": null
          },
          "operator": {
            "color": "#F9F7F3",
            "font_style": null,
            "font_weight": null
          },
          "property": {
            "color": "#F9F7F3",
            "font_style": null,
            "font_weight": null
          },
          "string": {
            "color": "#A5C261",
            "font_style": null,
            "font_weight": null
          },
          "string.escape": {
            "color": "#A5C261",
            "font_style": null,
            "font_weight": null
          },
          "string.regex": {
            "color": "#A5C261",
            "font_style": null,
            "font_weight": null
          },
          "string.special": {
            "color": "#6D9CBE",
            "font_style": null,
            "font_weight": null
          },
          "string.special.symbol": {
            "color": "#6D9CBE",
            "font_style": null,
            "font_weight": null
          },
          "tag": {
            "color": "#DA4939",
            "font_style": null,
            "font_weight": null
          },
          "text.literal": {
            "color": "#A5C261",
            "font_style": null,
            "font_weight": null
          },
          "type": {
            "color": "#FFC66D",
            "font_style": null,
            "font_weight": null
          },
          "variable": {
            "color": "#DA4939",
            "font_style": null,
            "font_weight": null
          },
          "variable.special": {
            "color": "#FFC66D",
            "font_style": null,
            "font_weight": null
          }
        }
      }
    }
  ]
}

Published as https://zed-themes.com/themes/j4VgcRlkMC9BzlOOmOVOe?name=Railscasts%20Renewed%20Dark .