opencode/packages/ui/src/components/dock-surface.css

[data-dock-surface="shell"] {
  background-color: var(--surface-raised-stronger-non-alpha);
  box-shadow: var(--shadow-xs-border);
  position: relative;
  z-index: 10;
  border-radius: 12px;
  overflow: clip;
}

[data-dock-border-underlay] {
  /* Later shadows paint underneath, so this solid ring masks overlapping surfaces without changing border geometry. */
  box-shadow:
    var(--dock-shell-visual-shadow, var(--shadow-xs-border)),
    0 0 0 var(--dock-shell-border-underlay-width, 1px)
      var(--dock-shell-border-underlay-background, var(--surface-raised-stronger-non-alpha));
}

[data-dock-border-underlay="v2"] {
  --dock-shell-visual-shadow: var(--v2-elevation-raised);
  --dock-shell-border-underlay-width: 0.5px;
  --dock-shell-border-underlay-background: var(--v2-background-bg-base);
}

[data-dock-surface="tray"] {
  background-color: var(--background-base);
  border: 1px solid var(--border-weak-base);
  position: relative;
  z-index: 0;
  border-radius: 12px;
  overflow: clip;
}

[data-dock-surface="tray"][data-dock-attach="top"] {
  margin-top: -0.875rem;
  border-top-left-radius: 0;
  border-top-right-radius: 0;
}