/* ============================================================
   layout.css — 顶部导航、页面布局、移动优先 + 768px 断点
   ============================================================ */

/* ---------------- 顶部导航（移动优先） ---------------- */

.site-navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: #fff;
  border-bottom: 1px solid var(--color-border-light);
  box-shadow: var(--shadow-sm);
}

.navbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  min-height: var(--navbar-height);
  position: relative;
  flex-wrap: wrap;
  padding-top: 4px;
  padding-bottom: 4px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  font-size: 16px;
  color: var(--color-text);
  white-space: nowrap;
}

.brand:hover {
  text-decoration: none;
  color: var(--color-primary);
}

.brand-logo {
  width: 28px;
  height: 28px;
  flex: none;
}

.brand-name {
  overflow: hidden;
  text-overflow: ellipsis;
}

/* 汉堡按钮：移动端可见 */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 36px;
  font-size: 20px;
  line-height: 1;
  color: var(--color-text);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  background: #fff;
}

.nav-toggle:active {
  background: var(--color-bg-hover);
}

/* 移动端：菜单折叠为下拉面板 */
.nav-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: #fff;
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-md);
  padding: 8px 16px 12px;
  z-index: 99;
}

.nav-menu.nav-open {
  display: block;
}

.nav-link {
  display: block;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  font-weight: 500;
}

.nav-link:hover {
  text-decoration: none;
  background: var(--color-bg-hover);
  color: var(--color-text);
}

.nav-link.active {
  color: var(--color-primary);
  background: var(--color-primary-light);
}

.nav-auth {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  padding: 10px 12px 4px;
  border-top: 1px solid var(--color-border-light);
  margin-top: 6px;
}

.nav-user {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  color: var(--color-text);
  min-width: 0;
}

.nav-username {
  max-width: 140px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-weight: 500;
}

/* ---------------- 主内容与页脚 ---------------- */

.app-main {
  flex: 1;
  min-width: 0;
  padding: 16px 16px 48px;
}

.site-footer {
  border-top: 1px solid var(--color-border-light);
  background: #fff;
  padding: 14px 16px;
  text-align: center;
  font-size: 12px;
  color: var(--color-text-muted);
}

/* ---------------- 页面通用结构 ---------------- */

.page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.page-title {
  font-size: 1.25rem;
}

.page-subtitle {
  font-size: 13px;
  color: var(--color-text-secondary);
  margin-top: 2px;
}

/* 表单页（登录/注册/账号创建）居中卡片 */
.form-card {
  max-width: 420px;
  margin: 24px auto 0;
  padding: 24px 20px;
}

.form-card.wide {
  max-width: 720px;
}

.form-card h1 {
  margin-bottom: 4px;
}

.form-card .form-lead {
  font-size: 13px;
  color: var(--color-text-secondary);
  margin-bottom: 18px;
}

.form-alt-link {
  margin-top: 16px;
  font-size: 13px;
  color: var(--color-text-secondary);
  text-align: center;
}

/* ---------------- ≥768px 桌面布局 ---------------- */

@media (min-width: 768px) {
  .nav-toggle {
    display: none;
  }

  .nav-menu {
    display: flex;
    align-items: center;
    gap: 2px;
    position: static;
    padding: 0;
    border: none;
    box-shadow: none;
    background: transparent;
    margin-left: auto;
  }

  .nav-link {
    padding: 7px 12px;
    font-size: 14px;
  }

  .nav-auth {
    border-top: none;
    margin-top: 0;
    margin-left: 10px;
    padding: 0 0 0 10px;
    border-left: 1px solid var(--color-border-light);
  }

  .app-main {
    padding: 24px 24px 64px;
  }

  .form-card {
    padding: 32px 32px 28px;
  }
}