Suggestion: I changed the code to use transparent colors; If you like, you can include it in a new update:
//var wmeSpeedsColors = ['#ff0000', '#321325', '#540804', '#BA1200', '#FA4A48', '#F39C6B', '#A7D3A6', '#ADD2C2', '#CFE795', '#F7EF81', '#BDC4A7', '#95AFBA', '#3F7CAC', '#0A369D', '#001C55'];
var wmeSpeedsOpacityColor = '0.4';
var wmeSpeedsColors = ['rgba(255,0,0,'+wmeSpeedsOpacityColor+')', 'rgba(50,19,37,'+wmeSpeedsOpacityColor+')', 'rgba(84,8,4,'+wmeSpeedsOpacityColor+')', 'rgba(186,18,0,'+wmeSpeedsOpacityColor+')',
'rgba(250,74,72,'+wmeSpeedsOpacityColor+')', 'rgba(243,156,107,'+wmeSpeedsOpacityColor+')', 'rgba(167,211,166,'+wmeSpeedsOpacityColor+')',
'rgba(173,210,194,'+wmeSpeedsOpacityColor+')', 'rgba(207,231,149,'+wmeSpeedsOpacityColor+')', 'rgba(247,239,129,'+wmeSpeedsOpacityColor+')',
'rgba(189,196,167,'+wmeSpeedsOpacityColor+')', 'rgba(149,175,186,'+wmeSpeedsOpacityColor+')', 'rgba(63,124,172,'+wmeSpeedsOpacityColor+')',
'rgba(10,54,157,'+wmeSpeedsOpacityColor+')', 'rgba(0,28,85,'+wmeSpeedsOpacityColor+')'];