body{background-color:#000;color:#fff}.navbar-logo{margin-bottom:-3rem;width:100px;height:auto}.button-submit-art{width:90%;font-size:20px;margin-left:5rem;padding:1rem;height:auto;transition:transform .2s ease-in-out}.button-submit-art:hover{transform:scale(1.05)}.button-chapter{width:90%;margin-left:5rem}.menu-item,.menu-list{background-color:orange}.menu-item{color:#000}.menu-item:hover{background-color:#000;color:orange}.flip-card{perspective:1000px}.flip-card-inner{position:relative;width:100%;height:100%;text-align:center;transition:transform .6s;transform-style:preserve-3d;will-change:transform}.flip-card-inner.flipped{transform:rotateY(180deg)}.flip-card-side{position:absolute;width:100%;height:100%;-webkit-backface-visibility:hidden;backface-visibility:hidden;will-change:transform}.flip-card-back{transform:rotateY(180deg)}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}@keyframes slideIn{0%{transform:translateY(20px);opacity:0}to{transform:translateY(0);opacity:1}}.fade-in{animation:fadeIn 1s ease-in-out}.slide-in{animation:slideIn .5s ease-in-out}.btc-price{font-size:20px;color:orange}