.contenedor_loader {
    background-color: #000000;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;      /* FIX: antes estaba 100vw (causaba overflow) */
    height: 100%;
    z-index: 9999;
    transition: opacity 1.5s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;  /* Previene desplazamientos horizontales */
}

.loader,
.loader::before,
.loader::after {
    border-radius: 50%;
    width: 2.5em;
    height: 2.5em;
    animation: loader 1.5s infinite ease-in-out;
}

.loader {
    color: #ffffff;
    font-size: 13px;
    position: relative;
    animation-delay: -0.16s;
}

.loader::before,
.loader::after {
    content: '';
    position: absolute;
    top: 0;
}

.loader::before {
    left: -3.5em;
    animation-delay: -0.32s;
}

.loader::after {
    left: 3.5em;
}

@keyframes loader {
    0%,
    80%,
    100% {
        box-shadow: 0 2.5em 0 -1.3em;
    }
    40% {
        box-shadow: 0 2.5em 0 0;
    }
}