v1.2.0

feature complement the effect of gradient on background color and correct the blending mode of mixed colors（补充渐变对背景色的影响，并修正混合颜色的混合模式）
bugfix fix the issue where the background color of an element would be processed repeatedly when it matched its complementary color（修复元素背景色与补色一致时会被重复处理的问题）