/* Static mobile scenery: the canvas, box art and game physics remain untouched. */
@media (max-width:700px) {
  #stack .ob-arena {
    isolation:isolate;
    border-radius:12px;
    background:
      radial-gradient(ellipse at 50% 43%,#87929b36,transparent 58%),
      linear-gradient(180deg,#08090c4d 0%,#08090b38 65%,#050607cc 100%);
    box-shadow:inset 0 0 0 1px #ffffff0a,inset 0 -24px 40px #0005;
  }
  #stack .ob-arena::before {
    content:"";
    position:absolute;
    inset:0;
    z-index:-2;
    border-radius:inherit;
    pointer-events:none;
    background:
      radial-gradient(ellipse at 50% 46%,#b5c3cc38 0%,#090b1000 55%),
      radial-gradient(ellipse at 9% 67%,#ad1d2925,transparent 39%),
      radial-gradient(ellipse at 94% 28%,#9f1d2720,transparent 34%),
      repeating-linear-gradient(0deg,transparent 0 47px,#c0c7ce08 48px,transparent 49px 96px),
      linear-gradient(112deg,transparent 15%,#a3192538 15.3%,transparent 16.1%,transparent 83%,#bd202532 83.3%,transparent 84%),
      linear-gradient(#080a0e8f,#08090c99),
      url('stack-background.jpg') 50% 44% / auto 112% no-repeat;
    /* A tiny static blur softens the scenery without filtering the game canvas. */
    filter:blur(.6px);
  }
  #stack .ob-arena::after {
    content:"";
    position:absolute;
    left:8%;right:8%;top:92%;height:4%;
    z-index:-1;
    pointer-events:none;
    border:1px solid #6c70733d;
    border-top:2px solid #b0b5b660;
    border-radius:50%;
    background:
      linear-gradient(90deg,transparent,#9b1e2852 20%,#777b7c33 50%,#9b1e283b 80%,transparent),
      repeating-linear-gradient(100deg,#25282b 0 2px,#181b1d 3px 9px);
    box-shadow:0 6px 0 #0c0e10,0 13px 18px 5px #000b,0 -7px 25px #b0222226;
  }
  #stack canvas {position:relative;z-index:0}
  #stack .ob-arena-foot {z-index:1;color:#c5c6c8;text-shadow:0 1px 4px #000}
}