/* Nút lùi to, có chữ, nằm góc trên trái, dính khi cuộn (cô Ari 06/10/2026). Dùng: <a class="nut-lui" href="…"><svg …/>Quay về</a> */
.nut-lui{position:fixed;z-index:60;left:max(12px,env(safe-area-inset-left));top:calc(10px + env(safe-area-inset-top));display:inline-flex;align-items:center;justify-content:center;gap:6px;
  min-width:52px;height:52px;padding:0 16px 0 12px;border-radius:999px;background:linear-gradient(180deg,#ffe9d2,#ffb46b);color:#1a0f22;font:700 .95rem/1 system-ui,-apple-system,"Be Vietnam Pro",sans-serif;text-decoration:none;
  box-shadow:0 0 0 4px rgba(255,180,107,.22),0 0 26px rgba(255,160,90,.6),inset 0 -4px 8px rgba(150,60,10,.25)}
.nut-lui svg{width:24px;height:24px;fill:none;stroke:currentColor;stroke-width:2.4;stroke-linecap:round;stroke-linejoin:round}
.nut-lui:hover{filter:brightness(1.08)}
.nut-lui:focus-visible{outline:3px solid #fff;outline-offset:3px}