/* ===== 主布局结构 ===== */
.app {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.app-header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(8px);
  background-color: rgba(255, 255, 255, 0.8);
  border-bottom: 1px solid var(--border-light);
  transition: background-color var(--transition), border-color var(--transition);
}

[data-theme="dark"] .app-header {
  background-color: rgba(15, 23, 42, 0.8);
}

.app-main {
  flex: 1 1 0%;
}

.app-footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-light);
  padding: var(--space-8) 0;
  transition: background-color var(--transition), border-color var(--transition);
}

/* ===== 导航栏 ===== */
.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4rem;
}

.navbar-mobile {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.navbar-desktop {
  display: none;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

@media (min-width: 768px) {
  .navbar-mobile { display: none; }
  .navbar-desktop { display: flex; }
}

.navbar-menu-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius);
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-tertiary);
  cursor: pointer;
  transition: all var(--transition);
}

.navbar-menu-btn:hover {
  background-color: var(--gray-100);
  border-color: var(--border-dark);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-primary);
  text-decoration: none;
}

.logo i {
  color: var(--primary);
}

.logo-text {
  display: none;
}

@media (min-width: 640px) {
  .logo-text { display: inline; }
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius);
  transition: all var(--transition);
}

.nav-link:hover {
  color: var(--primary);
  background-color: var(--gray-100);
}

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

.theme-toggle {
  margin-left: var(--space-4);
}

.theme-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius);
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-tertiary);
  cursor: pointer;
  transition: all var(--transition);
}

.theme-btn:hover {
  background-color: var(--gray-100);
  border-color: var(--border-dark);
}

/* ===== 英雄区域 ===== */
.hero {
  padding: var(--space-12) 0;
  text-align: center;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  color: white;
  margin-bottom: var(--space-8);
}

.hero-content {
  max-width: 48rem;
  margin: 0 auto;
}

.hero-title {
  font-size: 3rem;
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: var(--space-4);
  color: white;
}

.hero-description {
  font-size: 1.25rem;
  opacity: 0.9;
  margin-bottom: var(--space-6);
  color: rgba(255, 255, 255, 0.9);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  justify-content: center;
  margin-bottom: var(--space-8);
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-6);
  max-width: 32rem;
  margin: 0 auto;
}

@media (min-width: 640px) {
  .hero-stats {
    grid-template-columns: repeat(4, 1fr);
  }
}

.stat {
  text-align: center;
}

.stat-number {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: var(--space-1);
}

.stat-label {
  font-size: 0.875rem;
  opacity: 0.8;
}

@media (min-width: 768px) {
  .hero-title { font-size: 3.5rem; }
  .hero-description { font-size: 1.5rem; }
}

@media (min-width: 1024px) {
  .hero-title { font-size: 4rem; }
}

/* ===== 网格系统 ===== */
.features-grid {
  display: grid;
  gap: var(--space-6);
  grid-template-columns: 1fr;
}

@media (min-width: 768px) {
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .features-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.categories-grid {
  display: grid;
  gap: var(--space-6);
  grid-template-columns: 1fr;
}

@media (min-width: 640px) {
  .categories-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .categories-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.tools-grid {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: 1fr;
}

@media (min-width: 640px) {
  .tools-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .tools-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (min-width: 1280px) {
  .tools-grid {
    grid-template-columns: repeat(5, 1fr);
  }
}

.guide-steps {
  display: grid;
  gap: var(--space-6);
  grid-template-columns: 1fr;
}

@media (min-width: 768px) {
  .guide-steps {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .guide-steps {
    grid-template-columns: repeat(4, 1fr);
  }
}

.footer-grid {
  display: grid;
  gap: var(--space-8);
  grid-template-columns: 1fr;
}

@media (min-width: 768px) {
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .footer-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* ===== 计算器布局 ===== */
.calculator-layout {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

@media (min-width: 1024px) {
  .calculator-layout {
    flex-direction: row;
  }
  
  .calculator-sidebar {
    flex: 0 0 20rem;
  }
  
  .calculator-main {
    flex: 1 1 0%;
  }
}

.calculator-container {
  max-width: 32rem;
  margin: 0 auto;
}

.calculator-card {
  background-color: var(--bg-primary);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-light);
  padding: var(--space-6);
  box-shadow: var(--shadow-md);
}

/* ===== 页脚 ===== */
.footer-logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-primary);
  text-decoration: none;
  margin-bottom: var(--space-4);
}

.footer-logo i {
  color: var(--primary);
}

.footer-description {
  font-size: 0.875rem;
  color: var(--text-tertiary);
  margin-bottom: var(--space-4);
}

.social-links {
  display: flex;
  gap: var(--space-3);
}

.social-links a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius);
  background-color: var(--gray-100);
  color: var(--text-secondary);
  transition: all var(--transition);
}

.social-links a:hover {
  background-color: var(--primary);
  color: white;
  transform: translateY(-2px);
}

.footer-heading {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
}

.footer-link {
  display: block;
  font-size: 0.875rem;
  color: var(--text-tertiary);
  text-decoration: none;
  margin-bottom: var(--space-2);
  transition: color var(--transition);
}

.footer-link:hover {
  color: var(--primary);
}

.footer-bottom {
  margin-top: var(--space-8);
  padding-top: var(--space-6);
  border-top: 1px solid var(--border-light);
  text-align: center;
}

.footer-bottom p {
  font-size: 0.875rem;
  color: var(--text-tertiary);
  margin-bottom: var(--space-1);
}

.footer-note {
  font-size: 0.75rem;
  opacity: 0.7;
}

/* ===== 移动端底部导航 ===== */
.mobile-bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background-color: var(--bg-primary);
  border-top: 1px solid var(--border-light);
  padding: var(--space-2) 0;
  z-index: 40;
  display: flex;
  justify-content: space-around;
  transition: background-color var(--transition), border-color var(--transition);
}

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

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-decoration: none;
  color: var(--text-tertiary);
  padding: var(--space-2);
  border-radius: var(--radius);
  transition: all var(--transition);
  flex: 1;
  max-width: 5rem;
}

.nav-item:hover {
  color: var(--primary);
}

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

.nav-icon {
  font-size: 1.25rem;
  margin-bottom: var(--space-1);
}

.nav-label {
  font-size: 0.75rem;
  font-weight: 500;
}

/* ===== 移动端菜单 ===== */
.mobile-menu {
  position: fixed;
  top: 0;
  right: -100%;
  bottom: 0;
  width: 100%;
  max-width: 20rem;
  background-color: var(--bg-primary);
  border-left: 1px solid var(--border-light);
  z-index: 60;
  transition: right var(--transition);
  display: flex;
  flex-direction: column;
}

.mobile-menu.active {
  right: 0;
}

.mobile-menu-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4);
  border-bottom: 1px solid var(--border-light);
}

.mobile-menu-header h3 {
  margin-bottom: 0;
  font-size: 1.25rem;
}

.mobile-menu-close {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius);
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-tertiary);
  cursor: pointer;
  transition: all var(--transition);
}

.mobile-menu-close:hover {
  background-color: var(--gray-100);
  border-color: var(--border-dark);
}

.mobile-menu-content {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-4);
}

.mobile-menu-link {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius);
  color: var(--text-primary);
  text-decoration: none;
  margin-bottom: var(--space-2);
  transition: all var(--transition);
}

.mobile-menu-link:hover {
  background-color: var(--gray-100);
  color: var(--primary);
}

.mobile-menu-divider {
  margin: var(--space-4) 0;
  border: none;
  border-top: 1px solid var(--border-light);
}

/* ===== 面包屑导航 ===== */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-6);
  flex-wrap: wrap;
}

.breadcrumb-item {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.breadcrumb-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  transition: var(--transition);
}

.breadcrumb-link:hover {
  color: var(--primary);
}

.breadcrumb-current {
  color: var(--text-primary);
  font-size: 0.875rem;
  font-weight: 500;
}

.breadcrumb-divider {
  color: var(--text-tertiary);
  font-size: 0.75rem;
}