anchor.diff:  header.App-header
     h1.App-header-heading math24
     button.App-header-generate(onClick=this.onGenerate) generate
  -  
  +
   input.App-input(onChange=this.onChange autoFocus placeholder='Combine the numbers below to make 24')
   
   .App-nums
  
positive.code:     var val = ev.target.value;
      var nums = this.state.nums.slice();
      var numsArr = val
        .replace(/\s/g, '')
        .replace(/[\+\*\-\//\(\)]/g, ',')
        .split(',')
      var numsStatus = numsArr
        .reduce((acc, next, idx) => {
  
negative.code:     var className = isActive ? 'is-active' : ''
      .App-nums-num(className=className)= n
  
  var res = state.numsStatus && Object.keys(state.numsStatus).length && state.res || '-'
  var className = state.isCorrect ? 'is-active' : ''
  .App-result(className=className)= res