How do you convert RGBColor to an HTML-style string?

Seems like the function I was wanting was:

hexifyColor[color_RGBColor] := 
  StringJoin["#", IntegerString[Round[Level[color, 1]*255], 16, 2]]

It is there, deep down, but I'm too lazy to dig...

hexColor = StringCases[
    ExportString[Style[1, #], "HTMLFragment"], 
    "color:" ~~ color__ ~~ "\"" :> color
][[1]] &


hexColor@Blue

"#0000ff"

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