/* ============================================
    Final layer: scrollbar, selection, POLISH 
   print, a11y, utilities, perf hints
   ============================================ */

/* Scrollbar */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }
* { scrollbar-width: thin; scrollbar-color: var(--border) transparent; }

/* Selection */
::selection {
    background: rgba(129, 140, 248, 0.3);
    color: var(--text-primary);
}

/* Focus */
:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
    border-radius: var(--radius-md);
}

/* Smooth scroll */
html {
    scroll-behavior: smooth;
    scroll-padding-top: calc(var(--header-height) + 24px);
}

/* Images */
img { max-width: 100%; height: auto; display: block; }

/* Utilities */
.text-gradient {
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.sr-only {
    position: absolute; width: 1px; height: 1px;
    padding: 0; margin: -1px; overflow: hidden;
    clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}

/* Prevent layout shift */
body { min-height: 100vh; overflow-x: hidden; }

/* Performance  only during interaction */hints 
.exercise-card:hover,
.btn:hover { will-change: transform; }

/* Print */
@media print {
    .header, .footer, .burger-menu, .modal-overlay { display: none !important; }
    * { background: white !important; color: black !important; box-shadow: none !important; }
    .container { max-width: 100%; padding: 0; }
}