/* Flecha de scroll */
.scroll-arrow {
     position: fixed;
     right: 20px;
     bottom: 20px;
     width: 48px;
     height: 48px;
     border-radius: 50%;
     background: #131313;
     color: #fff;
     display: flex;
     align-items: center;
     justify-content: center;
     font-size: 1.2rem;
     border: none;
     cursor: pointer;
     box-shadow: 0 6px 18px rgba(0,0,0,0.25);
     opacity: 0;
     transform: translateY(20px);
     transition: opacity .28s ease, transform .28s ease;
     z-index: 9999;
}
.scroll-arrow.show {
     opacity: 1;
     transform: translateY(0);
}

@media (max-width: 480px) {
     .scroll-arrow { right: 12px; bottom: 12px; width: 44px; height: 44px; }
}