*, &::before, &::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --mc: rgb(50, 200, 255);
    --lc: #fff;
    --dc: #333;
    --vc: rgb(0, 175, 0);
    --ec: rgb(255, 0, 0);
    --cc: rgb(0, 0, 200);
    --rc: brown;
}

main {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    .lien-accueil {
        all: unset;
        position: sticky;
        top: 0;
        z-index: 1000;
        display: inline-block;
        width: 100%;
        background: var(--mc);
        text-align: center;
        padding: 10px 0;
        color: var(--lc);
        text-transform: uppercase;
        cursor: pointer;
        transition: 0.2s ease-in-out;
        &:hover {
            padding: 20px 0px;
        }
    }
    .lien-top {        
        all: unset;
        position: fixed;
        bottom: 20px;
        right: 20px;
        display: inline-block;
        width: 40px;
        height: 40px;
        border-radius: 50px;
        background: var(--mc);
        display: flex;
        align-items: center;
        justify-content: center;
        box-shadow: 0 4px 8px rgba(0,0,0,0.3);
        cursor: pointer;
        transition: 0.3s ease;
        z-index: 1000;
        opacity: 0;
        transform: translateY(20px);
        pointer-events: none; /* pas cliquable quand invisible */
        transition: opacity 0.3s ease, transform 0.3s ease;
        &:hover {
            background: rgb(50, 200, 255, 0.8);
        }
        &.visible {
            opacity: 1;
            transform: translateY(0);
            pointer-events: auto;
        }
    }
}