*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  height: 100%;
  overflow: hidden;
  font-family: var(--font-family);
  font-size: var(--font-size-md);
  line-height: var(--line-height);
  color: var(--text-primary);
  background: var(--bg-app);
}

.sf-app {
  display: flex;
  flex-direction: column;
  height: 100vh;
  overflow: hidden;
}

.sf-main {
  display: flex;
  flex: 1;
  overflow: hidden;
  position: relative;
}

.sf-canvas {
  flex: 1;
  position: relative;
  overflow: hidden;
  background: var(--bg-canvas);
}

#paper {
  width: 100%;
  height: 100%;
}

/* WCAG 2.4.7 — Visible focus indicators for keyboard navigation */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 1px;
}

/* Remove default outline when using mouse (focus without focus-visible) */
:focus:not(:focus-visible) {
  outline: none;
}

/* ── Mobile layout ─────────────────────────────────────────────── */
@media (max-width: 768px) {
  .sf-main {
    flex-direction: column;
  }

  .sf-canvas {
    flex: 1;
    min-height: 0;
  }
}