attach.html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{margin: 0; padding: 0; box-sizing: border-box;}
        div {
            width: 100%;
            height: 100vh;
            background-size: cover;
            background-attachment: fixed;
        }
        div:nth-child(1) {
            background-image: url(../img/img_lights1.jpg);
        }
        div:nth-child(2) {
            background-image: url(../img/img_lights2.jpg);
        }
        /* ⭐ 요소는 움직이지만 이미지는 고정 ⭐ */
    </style>
</head>
<body>
    <div></div>
    <div></div>
    
</body>
</html>
 
 
 
 
    
    
  
swatch.html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{margin: 0;padding: 0;box-sizing: border-box;}
        li {list-style: none;}
        a {color: inherit; text-decoration: none;}
        #wrap {
            width: 100%;
            height: 100vh;
            margin: 0 auto;
        }
    /* 상단 */
        #header {
            width: 100%;
            display: flex;
            justify-content: space-between;
            padding: 20px;
            position: fixed;
        }
        #header img {
            width: 150px;
        }
    /* 큰 이미지 */
        #imgBg > ul {
            width: 100%;
            height: 100vh;
            background-attachment: fixed;
            background-size: cover;
        }
        #imgBg .one {background-image: url(./swath_img/bg1.jpg); position: relative;}
        #imgBg .one li img {
            position: absolute;
            top: 15%;
            left: 15%;
        }
        /* #imgBg .one li img.on {left: 50%;} */
        #imgBg .one p.on {color: blueviolet;}
        #imgBg .two {background-image: url(./swath_img/bg2.jpg); position: relative;}
        #imgBg .two li img {
            position: absolute;
            top: 15%;
            left: 15%;
        }
        #imgBg .two p.on {color: blue;}
        #imgBg .three {background-image: url(./swath_img/bg3.jpg); position: relative;}
        #imgBg .three li img {
            position: absolute;
            top: 15%;
            left: 15%;
        }
        #imgBg .three p.on {color: brown;}
        #imgBg .four {background-image: url(./swath_img/bg4.jpg); position: relative;}
        #imgBg .four li img {
            position: absolute;
            top: 15%;
            left: 15%;
        }
        
        #imgBg .four p.on {color: lightseagreen;}
        #imgBg p {
            font-size: 50px;
            font-weight: bold;
            color: #555;
            position: relative;
            top: 45%;
            left: 300px;
        }
    /* 메뉴 */
        #leftMenu {
            width: 200px;
            height: 100vh;
            position: fixed;
            top: 0;
            left: 0;
            display: flex;
            flex-direction: column;
            justify-content: center;
        }
        #leftMenu li {
            padding: 10px 0;
            text-align: right;
            border-top: 1px solid #555;
            transition: 0.7s;
        }
        #leftMenu li:nth-child(1).on {
            border-top: 2px solid blueviolet;
            color: blueviolet;
            font-weight: bold;
        }
        #leftMenu li:nth-child(2).on {
            border-top: 2px solid blue;
            color: blue;
            font-weight: bold;
        }
        #leftMenu li:nth-child(3).on {
            border-top: 2px solid brown;
            color: brown;
            font-weight: bold;
        }
        #leftMenu li:nth-child(4).on {
            border-top: 2px solid lightseagreen;
            color: lightseagreen;
            font-weight: bold;
        }
    </style>
</head>
<body>
    <div id="wrap">
        <div id="header">
            <ul><img src="./swath_img/logo.png" alt=""></ul>
            <ul><img src="./swath_img/sns_흑백.png" alt=""></ul>
        </div>
        <div id="imgBg">
            <ul class="one">
                <li>
                    <img src="./swath_img/obj12.png" alt="">
                    <img src="./swath_img/obj11.png" alt="">
                    <img src="./swath_img/obj13.png" alt="">
                </li>
                <p>Full Blossom</p>
            </ul>
            <ul class="two">
                <li>
                    <img src="./swath_img/obj21.png" alt="">
                    <img src="./swath_img/obj22.png" alt="">
                </li>
                <p>Be Colorful</p>
            </ul>
            <ul class="three">
                <li>
                    <img src="./swath_img/obj31.png" alt="">
                    <img src="./swath_img/obj32.png" alt="">
                    <img src="./swath_img/obj33.png" alt="">
                </li>
                <p>Time on Board</p>
            </ul>
            <ul class="four">
                <li>
                    <img src="./swath_img/obj41.png" alt="">
                    <img src="./swath_img/obj42.png" alt="">
                </li>
                <p>Shiny Addict</p>
            </ul>
        </div>
        <div id="leftMenu">
            <ul>
                <li>
                    <a href=""></a>
                    Full Blossom
                </li>
                <li>
                    <a href=""></a>
                    Be Colorful
                </li>
                <li>
                    <a href=""></a>
                    Time on Board
                </li>
                <li>
                    <a href=""></a>
                    Shiny Addict
                </li>
            </ul>
        </div>
    </div>
    <script>
        let lis = document.querySelectorAll('#leftMenu > ul > li');
        let Ps = document.querySelectorAll('ul p');
        // let img = document.querySelector;
        let wh = window.innerHeight; 
        
        // ⭐클릭시 이동
    // (1)
        lis.forEach((li, index) => {
            li.addEventListener('click', function() {
                window.scrollTo({top: index*wh, behavior:'smooth'});
            })
        })
    // (2)
        // lis[0].addEventListener('click', function() {
        //     window.scrollTo({top:0});
        // })
        // lis[1].addEventListener('click', function() {
        //     window.scrollTo({top:959});
        // })
        // lis[2].addEventListener('click', function() {
        //     window.scrollTo({top:1918});
        // })
        // lis[3].addEventListener('click', function() {
        //     window.scrollTo({top:2894});
        // })
        // ⭐스크롤시 메뉴 스타일 변경
        document.addEventListener('scroll', function() {
            let sct = document.documentElement.scrollTop;
            console.log(sct);
            for (let i=0; i<lis.length; i++) {
                if (sct >= wh*i && sct < wh*(i+1)) {
                    lis.forEach(li => li.classList.remove('on'));
                    lis[i].classList.add('on');
                }
                if (sct >= wh*i && sct < wh*(i+1)) {
                    Ps.forEach(li => li.classList.remove('on'));
                    Ps[i].classList.add('on');
                    console.log('색 바뀌는지 확인용')
                }
            }
        })
    </script>
</body>
</html>