#boite-a-idee-list ul {
    list-style: none;
    margin: 0;
}

#boite-a-idee-list ul > li {
    border-radius: 10px;
    margin: 20px 0;
    padding: 10px;
}

#boite-a-idee-list ul > li:nth-child(odd) {
    background: #efefef;
    color: #3a3a3a;
}

#boite-a-idee-list ul > li:nth-child(even) {
    background: #3a3a3a;
    color: #efefef;
}