/* ============================================================
   全局页面导航组件（移动端汉堡菜单）
   自包含：不依赖 styles.css 的变量，回测页等独立页面也能直接用。
   ============================================================ */

/* 汉堡按钮 */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 42px;
  height: 42px;
  padding: 0;
  border: 1px solid rgba(255, 255, 255, .35);
  border-radius: 9px;
  background: transparent;
  cursor: pointer;
  flex: 0 0 auto;
}
.nav-toggle span {
  display: block;
  height: 2px;
  width: 20px;
  margin: 0 auto;
  background: #fff;
  border-radius: 2px;
  transition: transform .2s, opacity .2s;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* 页面链接组 */
.page-nav {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-wrap: wrap;
}
.page-nav a {
  color: #e2e8f0;
  text-decoration: none;
  padding: 7px 12px;
  border-radius: 8px;
  font-size: 13.5px;
  line-height: 1.2;
  white-space: nowrap;
  transition: background .15s;
}
.page-nav a:hover { background: rgba(255, 255, 255, .14); }
.page-nav a.active { background: #6366f1; color: #fff; font-weight: 600; }

/* 桌面：顶栏内直接显示文字链接 */
@media (min-width: 821px) {
  .page-nav { display: flex; }
}

/* 移动：汉堡按钮 + 下拉面板 */
@media (max-width: 820px) {
  .nav-toggle { display: flex; }
  .page-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    background: #0f172a;
    border-top: 1px solid rgba(255, 255, 255, .12);
    box-shadow: 0 12px 28px rgba(0, 0, 0, .45);
    padding: 8px;
    display: none;
    z-index: 30;
  }
  .page-nav.open { display: flex; }
  .page-nav a { padding: 14px 16px; font-size: 16px; border-radius: 10px; }
}

/* 回测等独立页面用的顶栏外壳（自带深色背景，不依赖 styles.css） */
.bt-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
  padding: 12px 16px;
  background: #0f172a;
  color: #fff;
  position: sticky;
  top: 0;
  z-index: 30;
  box-shadow: 0 2px 12px rgba(0, 0, 0, .2);
}
.bt-topbar .brand { font-weight: 800; font-size: 16px; }