@media (max-width: 900px) {
  body {
    padding-top: 54px;
    padding-bottom: 66px;
  }

  /* Keep desktop untouched; mobile only */
  .layout {
    grid-template-columns: 1fr !important;
  }
  .left {
    position: fixed !important;
    top: 0;
    bottom: 0;
    left: 0;
    width: min(82vw, 320px) !important;
    z-index: 10030;
    transform: translateX(-105%);
    transition: transform .2s ease;
    box-shadow: 0 10px 32px rgba(0,0,0,.28);
    border-right: 1px solid #e5e7eb;
  }
  body.oc-menu-open .left {
    transform: translateX(0);
  }

  .mainColumn {
    grid-column: 1 !important;
  }

  /* remove debug subtitle on mobile */
  .centerTitleSub {
    display: none !important;
  }

  .oc-mobile-topbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 54px;
    z-index: 10040;
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 8px 10px;
    background: rgba(255,255,255,.97);
    border-bottom: 1px solid rgba(15,23,42,.12);
    backdrop-filter: blur(8px);
  }
  .oc-mobile-hamb {
    width: 38px;
    height: 38px;
    border: 0;
    border-radius: 10px;
    background: #0f172a;
    color: #fff;
    font-size: 20px;
    line-height: 1;
  }
  .oc-mobile-title {
    font-size: 14px;
    font-weight: 700;
    color: #0f172a;
  }

  .oc-mobile-overlay {
    position: fixed;
    inset: 0;
    background: rgba(2,6,23,.46);
    z-index: 10020;
    display: none;
  }
  body.oc-menu-open .oc-mobile-overlay {
    display: block;
  }

  .oc-mobile-bottom {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 10040;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
    padding: 10px 12px calc(10px + env(safe-area-inset-bottom));
    background: rgba(15,23,42,.92);
    border-top: 1px solid rgba(255,255,255,.12);
  }
  .oc-mobile-bottom button {
    min-height: 44px;
    border: 0;
    border-radius: 10px;
    color: #fff;
    font-size: 14px;
    font-weight: 700;
    background: rgba(255,255,255,.12);
  }
  .oc-mobile-bottom button.active {
    background: #2563eb;
  }
}