/**
 * 基础无障碍样式
 * 提供键盘导航、焦点可见性等基础无障碍支持
 */

/* ==================== 焦点样式 ==================== */

/* 确保焦点可见（仅键盘导航时显示） */
:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* 移除鼠标点击时的焦点框 */
:focus:not(:focus-visible) {
  outline: none;
}

/* 按钮焦点样式 */
.btn:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

/* 表单控件焦点样式 */
.form-control:focus-visible,
.form-select:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 0;
  border-color: var(--primary);
  box-shadow: 0 0 0 0.25rem rgba(59, 130, 246, 0.15);
}

/* 链接焦点样式 */
a:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* ==================== 跳过导航链接 ==================== */

.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--primary);
  color: white;
  padding: var(--space-sm) var(--space-md);
  text-decoration: none;
  border-radius: var(--radius-md);
  z-index: var(--z-tooltip);
  transition: top var(--duration-fast);
}

.skip-link:focus {
  top: var(--space-sm);
}

/* ==================== 屏幕阅读器专用文本 ==================== */

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

.sr-only-focusable:focus {
  position: static;
  width: auto;
  height: auto;
  padding: inherit;
  margin: inherit;
  overflow: visible;
  clip: auto;
  white-space: normal;
}

/* ==================== 键盘导航增强 ==================== */

/* 表格行键盘可访问 */
.table-modern tr[tabindex]:focus-visible {
  background-color: var(--primary-light);
  outline: 2px solid var(--primary);
  outline-offset: -2px;
}

/* 卡片键盘可访问 */
.mobile-card[tabindex]:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  box-shadow: var(--shadow-lg);
}

/* ==================== 对比度增强 ==================== */

/* 确保文本对比度符合WCAG AA标准 */
.text-secondary {
  /* 原色: --gray-600 (#4b5563) 已满足 4.5:1 */
  color: var(--text-secondary);
}

.text-tertiary {
  /* 提升对比度 */
  color: var(--gray-500);
}

/* ==================== 动画偏好设置 ==================== */

/* 尊重用户的减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ==================== 暗色模式下的焦点样式 ==================== */

[data-theme="dark"] :focus-visible {
  outline-color: var(--primary-light);
}

[data-theme="dark"] .form-control:focus-visible,
[data-theme="dark"] .form-select:focus-visible {
  border-color: var(--primary-light);
  box-shadow: 0 0 0 0.25rem rgba(96, 165, 250, 0.25);
}