background-image 이미지가 안나옵니다 ㅜ,ㅜ

body {
    font-family: 'Gowun Batang', serif; 
    font-size: 20px; 
    line-height: 1.2;
}

  .wrap {
    position: relative; 
    margin: 0 auto;  
    color: #000000;  
    overflow: hidden;
    }

  /* header */

  header {
    position: fixed;
    left: 0;
    top:0;
    width: 100%;
    height: 150px;
    background-color: #FFF5EA;
    padding: 40px 100px;
    box-sizing: border-box;
    border-bottom: 2px solid #fff;
    display: flex;
    justify-content: space-between;
}

header h1 {
    margin-left: 15px;
}

.gnb ul {
    display: flex;
    justify-content: flex-end;
}

.gnb ul li {
    color: #552F00;
    font-size: 1.1em;
    margin: 30px 40px 0 0;

}

/* main_section */




/* 슬라이드 */

article{
    width:100%; 
   height: 800px;
    background-color: mediumaquamarine; 
    margin-top: 100px;
}


article > div.banner > li {
    position: absolute;
}
 
   




article>div.banner li:nth-child(1){background-image: url(../images/official_main_banner_2800x854_1.jpg);}

article>div.banner li:nth-child(2){left:100%;background-image :url(../images/official_main_banner_2800x854_2.jpg);}

article>div.banner li:nth-child(3){left:200%;background-image: url(../images/official_main_banner_2800x854_3.jpg);}

article>div.banner li:nth-child(4){left:300%;background-image: url(../images/official_main_banner_2800x854_4.jpg);}

article>div.banner li:nth-child(5){left:400%;background-image: url(../images/official_main_banner_2800x854_1.jpg);}

찾아보니까 보통 경로 문제, 박스 사이즈 문제 둘 중 하나라는데

어디다가 크기를 줘야할지도 모르겠어요..

li에다가 줘야하는건가요?