/* ==========================================================================
   SCROLL UI — top progress bar (js/modules/scroll-progress.js) and the
   back-to-top button (js/modules/contact.js).
   ========================================================================== */

.progress-bar {
    position: fixed; top: 0; left: 0; width: 100%; height: 3px;
    background: rgba(255,255,255,.05);
    z-index: var(--z-header);
}
.progress-bar span {
    display: block; height: 100%; width: 0%;
    background: linear-gradient(90deg, var(--accent), var(--accent-2), var(--accent-3));
    box-shadow: 0 0 12px rgba(var(--accent-rgb), .8);
}

.back-to-top {
    position: fixed; bottom: 1.8rem; right: 1.8rem; z-index: 400;
    width: 46px; height: 46px; border-radius: 50%;
    background: var(--panel-strong); border: 1px solid var(--border);
    color: var(--text);
    display: flex; align-items: center; justify-content: center;
    opacity: 0; transform: translateY(12px); pointer-events: none;
    transition: opacity .3s, transform .3s, border-color .3s;
    backdrop-filter: blur(10px);
}
.back-to-top.is-visible { opacity: 1; transform: translateY(0); pointer-events: auto; }
.back-to-top:hover { border-color: rgba(var(--accent-rgb), .6); color: var(--accent); }