ENIGMA html_string

// Top of estring.cpp:
#include <iomanip>
#include <sstream>

// Wherever you like in estring.cpp:
string html_color(int x) {
  std::stringstream res;
  res << "#"
      << std::setbase(16) << std::setfill('0') << std::setw(6) << std::uppercase
      << (((x & 0xFF0000) >> 16) | (x & 0x00FF00) | ((x & 0x0000FF) << 16));
  return res.str();
}

// Wherever you like in estring.h:
string html_color(int x);