body {
    background: #0b0b0b;
    position: relative;
    overflow: hidden;
  }
  
  /* Subtle monitor noise */
  body::before {
    content: "";
    position: fixed;
    inset: 0;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)' opacity='0.04'/%3E%3C/svg%3E");
    pointer-events: none;
    z-index: 0;
  }
  
  /* Ambient HUD text layer */
  body::after {
    content:
      "SESSION: LOCAL\A"
      "MODE: SECURE\A"
      "INTEGRITY: OK\A\A"
      "NullFrag OS\A"
      "Build 19045.4046";
    position: fixed;
    top: 18px;
    left: 22px;
    white-space: pre;
    font-family: Consolas, \"Lucida Console\", monospace;
    font-size: 12px;
    line-height: 1.45;
    color: rgba(51, 255, 51, 0.28);
    pointer-events: none;
    z-index: 1;
  
    /* Slightly alive */
    animation: hudBreath 8s ease-in-out infinite;
  }
  
  /* Separate bottom-right OS label */
  @media (min-width: 768px) {
    body::after {
      background:
        linear-gradient(
          to bottom,
          transparent 0%,
          transparent 60%,
          rgba(0,0,0,0.25) 100%
        );
    }
  }
  
  /* Keep terminal above background */
  #cmd-window {
    position: relative;
    z-index: 2;
  }
  
  /* Very subtle breathing animation */
  @keyframes hudBreath {
    0%   { opacity: 0.22; }
    50%  { opacity: 0.32; }
    100% { opacity: 0.22; }
  }