voici le css met le a jour : 

*{
    margin:0;
    padding:0;
    box-sizing:border-box;
    font-family:'Poppins', Arial, sans-serif;
}

body{
    background:#fafafa;
    color:#111;
}


/* HEADER */

header{

    min-height:70vh;

    background:
    linear-gradient(
    rgba(0,0,0,.55),
    rgba(0,0,0,.65)
    ),
    url("olympe.jpg");


    background-size:cover;

    background-position:center;


    color:white;

    display:flex;

    align-items:center;

    justify-content:center;

    text-align:center;

    padding:30px;

}


.hero-btn{

    display:inline-block;

    margin-top:35px;

    padding:18px 45px;

    background:white;

    color:#111;

    border-radius:50px;

    text-decoration:none;

    font-size:18px;

    transition:.3s;

}


.hero-btn:hover{

    background:#e63946;

    color:white;

    transform:scale(1.05);

}

/* PRODUCT */

.container{
    max-width:1200px;
    margin:auto;
    padding:70px 25px;
}


.product-box{

    background:white;
    border-radius:35px;
    padding:50px;
    display:flex;
    gap:50px;
    align-items:center;

    box-shadow:
    0 20px 60px rgba(0,0,0,.08);

}


.product-box img{

    width:50%;
    border-radius:30px;

}



.info h2{

    font-size:40px;
    margin-bottom:5px;

}


.info p{

    font-size:18px;
    line-height:1.8;
    color:#555;

}


.price{

    font-size:30px;
    color:#e63946;
    font-weight:bold;
    margin:25px 0;

}


.buy{

    display:inline-block;
    background:#111;
    color:white;
    padding:18px 45px;
    border-radius:50px;
    text-decoration:none;
    font-size:18px;
    transition:.3s;

}


.buy:hover{

    background:#e63946;

}


/* BADGES */


.badges{

    display:flex;
    gap:20px;
    margin-top:50px;

}


.badge{

    background:white;
    padding:30px;
    border-radius:25px;
    flex:1;
    text-align:center;

    box-shadow:
    0 10px 30px rgba(0,0,0,.06);

}

li {
    margin: 8px 0;
    padding: 2px 0;
    display: flex;
    align-items: center;
}

li::before {
    content: "✓";
    background: #A8E6CF;
    color: white;
    width: 22px;
    height: 22px;
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: 50%;
    margin-right: 12px;
}


.badge h3{

    margin-bottom:10px;

}



/* REVIEWS */


.reviews{

    margin-top:60px;
    background:#111;
    color:white;
    padding:50px;
    border-radius:35px;
    text-align:center;

}


.review{

    margin-top:30px;
    background:#222;
    padding:25px;
    border-radius:20px;

}



/* OFFER */


.offer{

    margin-top:50px;
    text-align:center;
    background:#e63946;
    color:white;
    padding:50px;
    border-radius:35px;

}


.offer h2{

    font-size:40px;

}


.offer button{

    margin-top:25px;
    padding:18px 50px;
    border:none;
    border-radius:50px;
    cursor:pointer;
    font-size:18px;

}



/* FOOTER */


footer{

    background:#111;
    color:white;
    text-align:center;
    padding:30px;

}



/* MOBILE */


@media(max-width:800px){

.product-box{

    flex-direction:column;

}


.product-box img{

    width:100%;

}


.hero h1{

    font-size:40px;

}


.info h2{

    font-size:32px;

}


.badges{

    flex-direction:column;

}


/* SLIDER */

}

.slider{

    width:150%;
    overflow:hidden;
    position:relative;
    border-radius:30px;

}


.slides{

    display:flex;
    transition:0.5s ease;

}



.slides img{

    width:100%;
    height:450px;
    object-fit:cover;
    flex-shrink:0;
    border-radius:30px;

}




.prev,
.next{


    position:absolute;

    top:50%;

    transform:translateY(-50%);


    background:rgba(0,0,0,0.5);

    color:white;

    border:none;

    width:45px;

    height:45px;

    border-radius:50%;

    cursor:pointer;

    font-size:20px;


}



.prev{

left:15px;

}



.next{

right:15px;

}





@media(max-width:800px){


.slider{

width:100%;

}


.slides img{

height:350px;

}


}