Discussion on M&M - Creative One Page Portfolio

theme.min.css
start from line # 566
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.section-overlay{position:relative;}
.section-overlay:after{content:'';width:100%;height:100%;position:absolute;left:0;top:0;background:#fff;opacity:.9;z-index:0;}
.section-overlay-dark{position:relative;}
.section-overlay-dark:after{content:'';width:100%;height:100%;position:absolute;left:0;top:0;background:rgba(19, 19, 19, 0.7);z-index:0;}
.section-overlay-video{position:relative;}
.section-overlay-video:after{content:'';width:100%;height:100%;position:absolute;left:0;top:0;background:rgba(255, 255, 255, 0.86);z-index:-1;}