Theming

Neutral by default (grayscale, host font, 10px radius). theme="auto" (or "system") follows the OS (unless a host .light / data-theme="light" / data-bs-theme="light" is set) and a host .dark / data-theme="dark" / data-bs-theme="dark"; pass "light" or "dark" to force one. Match your design system with CSS variables on :root:

:root {
  --sideagent-accent: var(--primary);      /* buttons */
  --sideagent-accent-fg: var(--primary-foreground);
  --sideagent-bg: var(--background);
  --sideagent-fg: var(--foreground);
  --sideagent-border: var(--border);
  --sideagent-surface: var(--muted);       /* user bubble, hovers */
  --sideagent-muted: var(--muted-foreground);
  --sideagent-radius: 10px;
  --sideagent-font: inherit;
}