html, body {
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif, sans-serif;
    font-size: var(--text-size-portable);
    background-color: var(--background-color);
    color: var(--text-color);
    text-align: center;
}

:root{
    --primary-color: #ffffff;
    --secondary-color: #9C2429;
    --secondary-color-hover: #D83239;
    --background-color: #ffffff;
    --secondary-background-color: #ECECEC;
    --tertiary-background-color: #000000;
    --books-background-color: linear-gradient(145deg,#989898 0%, #b2b2b2 40%, #989898 100%);
    --text-color: #ffffff;
    --box-text-color: #000000;
    --shadow-color: #989898b3;

    --h1-weight: 900;
    --h2-weight: 700;
    --h3-weight: 500;

    --taille-logo-portable:30px;

    --text-size-portable:1em;
    --text-navigation-taille: 15px;

    --h1-size-portable:2em;
    --h2-size-portable:1.5em;
    --h3-size-portable:1.25em;

    --heading-line-height-portable: 1;

    --padding-portable: 10px 30px 0px 30px;
    --gap-portable:10px;
    --gap-portable-navigation:15px;

    --button-padding: 10px 25px;
    --button-font-size: 1em;
    --button-border-radius: 20px;

    --width-couv-livre: 70vw;

    --drop-shadow: 5px 5px 5px var(--shadow-color);
    --drop-shadow-box: 1px 5px 5px var(--shadow-color);
}

.logo{
    height: auto;
    max-width: var(--taille-logo-portable);
}

h1{
    font-size: var(--h1-size-portable);
    font-weight: var(--h1-weight);
    line-height: var(--heading-line-height-portable);
    max-width: 90vw;
}

h2{
    font-size: var(--h2-size-portable);
    font-weight: var(--h2-weight);
    line-height: var(--heading-line-height-portable);
}

h3{
    font-size: var(--h3-size-portable);
    font-weight: var(--h3-weight);
    line-height: var(--heading-line-height-portable);
}

p{
    margin-bottom: var(--gap-portable);
}

.hero{
    background-image: var(--books-background-color);
}

.livre-content, .livre-content-hero{
    display:flex;
    flex-direction: column;
    align-items: center;   
    background-image: var(--books-background-color);
    padding: var(--padding-portable);
    margin-bottom: var(--gap-portable);
    height:auto;
}

.livre-content-hero{
    background-image: none;
}

.bar-navigation-header{
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--padding-portable);
}

header::after{
    content: "";
    display: block;
    height: 3px;
    width:50%;
    background-color: var(--secondary-background-color);
    border-radius: 20px;;
    margin: 10px auto;
    filter: drop-shadow(1px 2px 3px rgba(0, 0, 0, 0.37))
}

ul{
    list-style: none;
    padding: 0;
    margin: 0;
    display:flex;
    gap: var(--gap-portable);
    gap: var(--gap-portable-navigation);
}

a{
    text-decoration: none;
    color: var(--text-color);
    font-size: var(--text-navigation-taille);
}

a:hover{
    color: var(--secondary-color-hover);
    transition: color 0.3s ease;
}

.couverture-livre{
    height: auto;
    max-width: var(--width-couv-livre) ;
    margin-top: var(--gap-portable);
    margin-bottom: var(--gap-portable);
    filter: var(--drop-shadow);
}

.button{
    background-color: var(--secondary-color);
    color: var(--text-color);
    border: none;
    border-radius: var(--button-border-radius);
    padding: var(--button-padding);
    font-size: var(--button-font-size);
    filter: var(--drop-shadow);
    cursor: pointer;
    margin-bottom: var(--gap-portable);
}

.button:hover{
    background-color: var(--secondary-color-hover);
    transform: scale(1.05);
    transition: background-color 0.3s ease, transform 0.3s ease;
}

footer{
    background-color: var(--tertiary-background-color);
    color: var(--text-color);
    font-size: var(--text-navigation-taille);
    margin:0px;
    padding-bottom: 10px;
}

.groupe-liens-footer{
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--gap-portable);
}

.groupe-footer{
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--gap-portable);
}

.Infos-Achat-content{
    background-color: var(--secondary-background-color);
    padding: var(--padding-portable);
    max-width: var(--width-couv-livre);
    text-align: center;
    margin:auto;
    border-radius: 30px;
    filter: drop-shadow(var(--drop-shadow-box));
    color:var(--box-text-color);
    margin-bottom: var(--gap-portable);
}

.Prix{
    color:var(--secondary-color);
}

@media (min-width: 768px) {
    :root{
        --h1-size-portable:4em;
        --h2-size-portable:2em;
        --h3-size-portable:1.5em;

        --taille-logo-portable:50px;
        --text-navigation-taille: 20px;

        --heading-line-height-portable: 1;

        --padding-portable: 10px 30px 0px 30px;
        --gap-portable:20px;
        --gap-portable-navigation:25px;

        --width-couv-livre: 70vw;

        --button-padding: 15px 30px;
        --button-font-size: 1.4em;
        --button-border-radius: 30px;
    }

    .groupe-liens-footer{
         flex-direction: row;
         justify-content: space-around;
         margin-bottom: 30px;
         align-items: normal;
    }
}

@media (min-width: 1024px) {
    :root{
        --h1-size-portable:6em;
        --h2-size-portable:3em;
        --h3-size-portable:2em;

        --taille-logo-portable:60px;

        --heading-line-height-portable: 1.1;

        --padding-portable: 10px 30px 0px 30px;
        --gap-portable:20px;
        --gap-portable-navigation:30px;

        --button-padding: 15px 70px;
        --button-font-size: 1.6em;
        --button-border-radius: 50px;

        --width-couv-livre: 40vw;
}
    .livre-content{
        flex-direction: row;
        justify-content: center;
        align-items: normal;
    }

    .livre-content-hero{
        flex-direction: row;
        justify-content: center;
        align-items: normal;
    }

    .Titre-button{
        order: 2;
        text-align: left;
        margin-left:30px;
    }

    h1{
        margin-bottom:20px;
        max-width: 50vw;
    }
}