/* ============================================================
   SCROLL-RAIL: Laufbalken + "Nach oben"-Button links neben .site-content-inner (nur Desktop)
   Balken = Fortschritt (füllt sich), blendet bei Ruhe aus.  Button = immer mittig, bei Ruhe leicht transparent.
   Position (left) setzt js/js_tools/scroll_rail.js anhand des Containers.
============================================================ */
.sr {
    position: fixed; top: 0; bottom: 0; left: 0; width: 28px; z-index: 40;
    pointer-events: none; opacity: 0; transition: opacity .3s;
    --sr-sh: rgba(0,0,0,.55);
}
:root[data-theme="light"] .sr { --sr-sh: rgba(0,0,0,.18); }
.sr.is-on { opacity: 1; }
.sr.is-off { display: none; }
.sr__trk {
    position: absolute; left: 50%; top: 8px; bottom: 8px; width: 3px; margin-left: -1.5px; border-radius: 2px;
    background: #3b404e; opacity: 0; transition: opacity .35s;
}
.sr.is-scrolling .sr__trk { opacity: .2; }
.sr__fill { position: absolute; left: 0; top: 0; width: 100%; height: 0; border-radius: 2px; background: #b4bac8; }
:root[data-theme="light"] .sr__trk { background: #c9c6d3; }
:root[data-theme="light"] .sr__fill { background: #6c7080; }
.sr__btn {
    position: absolute; left: 0; top: 50%; transform: translateY(-50%); width: 28px; height: 24px; padding: 0;
    display: grid; place-items: center; pointer-events: auto; cursor: pointer;
    background: var(--bg-card, #1a1d26); color: var(--text-primary, #efeff5);
    border: 1px solid rgba(var(--ov-rgb, 255,255,255), .18); border-radius: 2px; box-shadow: 2px 2px 0 var(--sr-sh);
    opacity: .45; transition: opacity .3s, border-color .15s, color .15s;
}
.sr.is-scrolling .sr__btn, .sr__btn:hover, .sr__btn:focus-visible { opacity: 1; }
.sr__btn:hover { border-color: var(--accent, #f08228); color: var(--accent, #f08228); }
.sr__btn svg { display: block; }
@media (hover: none), (max-width: 900px) { .sr { display: none !important; } }
@media (prefers-reduced-motion: reduce) { .sr, .sr__trk, .sr__btn { transition: none; } }