getThemeCard = (themeName, selected) => {
  if(themeName === 'Custom Theme') return '<div></div>';
  let themeId = themeName.replace(' ', '');
  let selectedClass = selected ? 'selected set' : '';
  // themeSel is the hit area
  return `
            <div id="theme" class="theme ${selectedClass}">
              <div class='themeSel'></div>
              <span>${getThemeCardSvg(themeName)}</span>
              <span id='themeNameBox' class='themeNameBox'>
                <input type='radio' id='${themeId}' value='${themeName}' name='theme'>
                <label for='${themeId}'>${themeName}</label>
              </span>
            </div>
            `
}
Generates theme card HTML
@param {string} themeName Name of theme
@param {boolean} selected Flag variable for currently selected theme
@return {string} Theme card html