html { scroll-behavior: smooth; }
body { margin: 0; background: var(--yt-color-background); font-family: var(--font-family-persian); }
*, *::before, *::after { box-sizing: border-box; }
a { color: inherit; text-decoration: none; }
button, input { font: inherit; }
:focus-visible { outline: 3px solid var(--yt-color-focus); outline-offset: 3px; }
.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; }