html,body {
    padding: 0px;
    margin: 0px;
    height: 100%;
}

header.header__background {
    background-color: #313131;
}

.product-content {
    width: 1290px;
    margin: 0 auto;
    font-family: "Montserrat";
}

.product-content h1 {
    margin-top: 100px;
    font-weight: 800;
    font-size:36px;
    color: black;
}

.product-sub-content {
    display: flex;
    width: 100%;
    justify-content: space-between;
}

.product-description {
    width: 50%;
    font-size: 18px;
    font-weight: 500;
}

.product-description b {
    font-weight: 600;
}

.product-img {
    width: 40%;
}

.product-img img {
    width: 100%;
    border-radius: 15px;
}

.product-img .calibres ul {
    font-weight: 600;
    font-size: 24px;
    margin-top: 50px;
}

.product-img .calibres li {
    margin-top: 10px;
    margin-left: 20px;
    font-weight: 400;
    font-size: 18px;
}
@media only screen and (max-width: 819px) {
    body {
    height: 70%;
    }
    .product-content {
        width: 90%;
        margin: 0 auto;
        min-height: 100%;
    }

    .product-content h1 {
        margin-top: 100px;
        font-size: 18px;
    }

    .product-sub-content {
        flex-direction: column;
    }

    .product-description {
        margin-top: 20px;
        width: 100%;
        font-size: 12px;
    }

    .product-img {
        display: flex;
        width: 60%;
        margin-top: 30px;
        column-gap: 15px;
        align-items: start;
    }

    .product-img img {
        width: 100%;
    }

    .product-img .calibres ul {
        margin-top: 0px;
        font-size: 15px;
    }

    .product-img .calibres li {
        margin-left: 15px;
        margin-top: 5px;
        font-size: 10px;
    }
}