Section After Background Set Up Overlapping The Previous One

One section overlaps the other one. Are there any solutions? This is the first section:

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CSS:

.background{ 
        position: relative;
        overflow: hidden;
    }
    .background-curtain{
        position: absolute;
        width: 100%;
        height: 100%;
        background-image: linear-gradient(to top, black, white);opacity: 0.3;
        z-index: -100;
    }
    .background-some{
        background: url(background.jpeg);
        height: 60%;
        width: 100%;
    }

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