/* ======================================================================
   MODULE — BACK TO TOP
   Prefix: .m-btt
   ====================================================================== */

.m-btt {
    position: fixed;
    bottom: var(--sp-4);
    inset-inline-end: var(--sp-4);
    width: 44px;
    height: 44px;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: 50%;
    box-shadow: var(--shadow-md);
    cursor: pointer;
    z-index: var(--z-sticky);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transform: translateY(8px);
    transition: opacity var(--t-fast), transform var(--t-fast),
                visibility var(--t-fast), background var(--t-fast);
}

.m-btt.is-visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.m-btt:hover { background: var(--primary-dk); }
.m-btt:focus-visible { outline: 2px solid #fff; outline-offset: 3px; }

.m-btt svg {
    width: 18px;
    height: 18px;
    fill: none;
    stroke: currentColor;
    stroke-width: 2.5;
    stroke-linecap: round;
    stroke-linejoin: round;
}