/* ========================================
   KUNDE ELECTRIC - Global Styles
   ======================================== */

:root {
  /* 品牌色彩 */
  --primary-blue: #0A2E5C;
  --accent-red: #C41E3A;
  --white: #FFFFFF;
  --light-gray: #F5F5F5;
  --text-dark: #333333;
  --text-black: #000000;
  --text-muted: #666666;
  
  /* 间距 */
  --section-padding: 80px 0;
  --container-padding: 0 24px;
  
  /* 过渡 */
  --transition-fast: 200ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 300ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Reset */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-dark);
  background-color: var(--white);
}

/* 容器 */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--container-padding);
}

/* 按钮 */
.btn {
  display: inline-block;
  padding: 14px 32px;
  font-size: 16px;
  font-weight: 600;
  text-decoration: none;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: var(--transition-normal);
}

.btn-primary {
  background-color: var(--accent-red);
  color: var(--white);
}

.btn-primary:hover {
  background-color: #a01830;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(196, 30, 58, 0.3);
}

.btn-secondary {
  background-color: transparent;
  color: var(--white);
  border: 2px solid var(--white);
}

.btn-secondary:hover {
  background-color: var(--white);
  color: var(--primary-blue);
}

/* 标题 */
h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--primary-blue);
}

h1 { font-size: 56px; }
h2 { font-size: 40px; }
h3 { font-size: 28px; }

@media (max-width: 768px) {
  h1 { font-size: 36px; }
  h2 { font-size: 32px; }
  h3 { font-size: 24px; }
}

/* 章节标题 */
.section-title {
  text-align: center;
  margin-bottom: 48px;
}

.section-title h2 {
  margin-bottom: 16px;
}

.section-title p {
  color: var(--text-muted);
  font-size: 18px;
  max-width: 600px;
  margin: 0 auto;
}

/* ========================================
   Header & Navigation
   ======================================== */

.top-bar {
  background-color: var(--primary-blue);
  color: var(--white);
  padding: 10px 0;
  font-size: 14px;
}

.top-bar .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.social-links {
  display: flex;
  gap: 16px;
}

.social-links a {
  color: var(--white);
  text-decoration: none;
  transition: var(--transition-fast);
}

.social-links a:hover {
  color: var(--accent-red);
}

.header-main {
  background-color: var(--white);
  padding: 20px 0;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.header-main .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  display: flex;
  align-items: center;
  text-decoration: none;
}

.logo img {
  height: 70px;
  width: auto;
}

.header-contact {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 4px;
}

.header-contact a {
  color: var(--text-dark);
  text-decoration: none;
  font-size: 14px;
}

.header-contact a:hover {
  color: var(--accent-red);
}

/* 导航栏 */
.nav-bar {
  background-color: var(--primary-blue);
}

.nav-bar .container {
  display: flex;
  justify-content: center;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 0;
}

.nav-menu li a {
  display: block;
  padding: 16px 24px;
  color: var(--white);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition-fast);
  position: relative;
}

.nav-menu li a:hover,
.nav-menu li a.active {
  background-color: rgba(255,255,255,0.1);
}

.nav-menu li a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 2px;
  background-color: var(--accent-red);
  transition: var(--transition-fast);
}

.nav-menu li a:hover::after,
.nav-menu li a.active::after {
  width: 60%;
}

/* 汉堡菜单（移动端） */
.mobile-menu-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--white);
  font-size: 24px;
  cursor: pointer;
  padding: 8px;
}

@media (max-width: 1024px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--primary-blue);
    flex-direction: column;
    gap: 0;
  }
  
  .nav-menu.active {
    display: flex;
  }
  
  .nav-menu li a {
    padding: 14px 24px;
    border-bottom: 1px solid rgba(255,255,255,0.1);
  }
  
  .mobile-menu-toggle {
    display: block;
  }
  
  .header-main .container {
    position: relative;
  }
}

/* ========================================
   Hero Section (轮播图)
   ======================================== */

.hero {
  position: relative;
  height: 600px;
  overflow: hidden;
}

.hero-slider {
  position: relative;
  width: 100%;
  height: 100%;
}

.hero-slide {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  transition: opacity 1s ease-in-out;
}

.hero-slide.active {
  opacity: 1;
}

.hero-slide img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(rgba(10, 46, 92, 0.7), rgba(10, 46, 92, 0.5));
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
}

.hero-content {
  color: var(--white);
  max-width: 800px;
  padding: 0 24px;
}

.hero-content h1 {
  color: var(--white);
  margin-bottom: 16px;
  font-size: 64px;
}

.hero-content p {
  font-size: 24px;
  margin-bottom: 32px;
  opacity: 0.95;
}

.hero-buttons {
  display: flex;
  gap: 16px;
  justify-content: center;
}

@media (max-width: 768px) {
  .hero {
    height: 400px;
  }
  
  .hero-content h1 {
    font-size: 36px;
  }
  
  .hero-content p {
    font-size: 18px;
  }
  
  .hero-buttons {
    flex-direction: column;
  }
}

/* 轮播图控制点 */
.hero-dots {
  position: absolute;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 12px;
  z-index: 10;
}

.hero-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background-color: rgba(255,255,255,0.5);
  cursor: pointer;
  transition: var(--transition-fast);
}

.hero-dot.active {
  background-color: var(--white);
  transform: scale(1.2);
}

/* ========================================
   Product Section
   ======================================== */

.products-section {
  padding: var(--section-padding);
  background-color: var(--white);
}

.products-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

@media (max-width: 1024px) {
  .products-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .products-grid {
    grid-template-columns: 1fr;
  }
}

.product-card {
  background-color: var(--white);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  transition: var(--transition-normal);
}

.product-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 4px 16px rgba(0,0,0,0.15);
}

.product-card img {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.product-card-content {
  padding: 24px;
}

.product-card h3 {
  margin-bottom: 12px;
  font-size: 20px;
}

.product-card p {
  color: var(--text-muted);
  margin-bottom: 16px;
  font-size: 14px;
}

.product-card a {
  color: var(--accent-red);
  text-decoration: none;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: var(--transition-fast);
}

.product-card a:hover {
  gap: 12px;
}

/* ========================================
   Stats Section
   ======================================== */

.stats-section {
  padding: 60px 0;
  background-color: var(--primary-blue);
  color: var(--white);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 32px;
  text-align: center;
}

@media (max-width: 1024px) {
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .stats-grid {
    grid-template-columns: 1fr;
  }
}

.stat-item h3 {
  color: var(--white);
  font-size: 48px;
  margin-bottom: 8px;
}

.stat-item p {
  font-size: 16px;
  opacity: 0.9;
}

/* ========================================
   Production Line Section
   ======================================== */

.production-section {
  padding: var(--section-padding);
  background-color: var(--light-gray);
}

.production-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

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

@media (max-width: 480px) {
  .production-grid {
    grid-template-columns: 1fr;
  }
}

.production-card {
  position: relative;
  border-radius: 8px;
  overflow: hidden;
  aspect-ratio: 4/3;
}

.production-card img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: var(--transition-normal);
}

.production-card:hover img {
  transform: scale(1.05);
}

.production-card-overlay {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  background: linear-gradient(transparent, rgba(10, 46, 92, 0.9));
  padding: 24px;
  color: var(--white);
}

.production-card-overlay h4 {
  color: var(--white);
  font-size: 18px;
}

/* ========================================
   CTA Section
   ======================================== */

.cta-section {
  padding: 80px 0;
  background-color: var(--accent-red);
  text-align: center;
  color: var(--white);
}

.cta-section h2 {
  color: var(--white);
  margin-bottom: 16px;
}

.cta-section p {
  font-size: 18px;
  margin-bottom: 32px;
  opacity: 0.95;
}

.cta-section .btn {
  background-color: var(--white);
  color: var(--accent-red);
}

.cta-section .btn:hover {
  background-color: var(--light-gray);
}

/* ========================================
   Footer
   ======================================== */

.footer {
  background-color: var(--primary-blue);
  color: var(--white);
  padding: 60px 0 24px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 2fr;
  gap: 48px;
  margin-bottom: 48px;
}

@media (max-width: 1024px) {
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .footer-grid {
    grid-template-columns: 1fr;
  }
}

.footer-section h4 {
  color: var(--white);
  margin-bottom: 20px;
  font-size: 18px;
}

.footer-section p {
  color: #F8F9FA;
  line-height: 1.8;
}

.footer-section ul {
  list-style: none;
}

.footer-section ul li {
  margin-bottom: 12px;
}

.footer-section ul li a {
  color: #F8F9FA;
  text-decoration: none;
  transition: var(--transition-fast);
}

.footer-section ul li a:hover {
  opacity: 1;
  color: var(--accent-red);
}

.footer-contact-info {
  line-height: 2;
}

.footer-contact-info p {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 8px;
  color: #F8F9FA;
}

.footer-contact-info a {
  color: #F8F9FA;
}

.footer-social {
  display: flex;
  gap: 16px;
  margin-top: 16px;
}

.footer-social a {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background-color: rgba(255,255,255,0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--white);
  text-decoration: none;
  transition: var(--transition-fast);
}

.footer-social a:hover {
  background-color: var(--accent-red);
}

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.15);
  padding-top: 24px;
  text-align: center;
  color: #F8F9FA;
  font-size: 14px;
}

/* ========================================
   Page Header (内页顶部)
   ======================================== */

.page-header {
  background-color: var(--primary-blue);
  color: var(--white);
  padding: 80px 0;
  text-align: center;
}

.page-header h1 {
  color: var(--white);
  margin-bottom: 16px;
}

.page-header p {
  font-size: 18px;
  opacity: 0.9;
  max-width: 600px;
  margin: 0 auto;
}

/* ========================================
   About Page
   ======================================== */

.about-section {
  padding: var(--section-padding);
}

.about-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
  margin-bottom: 60px;
}

@media (max-width: 1024px) {
  .about-content {
    grid-template-columns: 1fr;
  }
}

.about-content img {
  width: 100%;
  max-width: 600px;
  height: auto;
  border-radius: 8px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.1);
  display: block;
  margin: 0 auto;
}

.about-text h2 {
  margin-bottom: 24px;
}

.about-text p {
  margin-bottom: 16px;
  color: var(--text-muted);
}

.advantages-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  margin-top: 60px;
}

@media (max-width: 768px) {
  .advantages-grid {
    grid-template-columns: 1fr;
  }
}

.advantage-card {
  text-align: center;
  padding: 32px 24px;
  background-color: var(--light-gray);
  border-radius: 8px;
  transition: var(--transition-normal);
}

.advantage-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 4px 16px rgba(0,0,0,0.1);
}

.advantage-card .icon {
  font-size: 48px;
  margin-bottom: 16px;
}

.advantage-card h3 {
  margin-bottom: 12px;
  font-size: 20px;
}

.advantage-card p {
  color: var(--text-muted);
  font-size: 14px;
}

/* ========================================
   Products Page
   ======================================== */

.products-page {
  padding: var(--section-padding);
}

.product-categories {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

@media (max-width: 1024px) {
  .product-categories {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .product-categories {
    grid-template-columns: 1fr;
  }
}

.category-card {
  background-color: var(--white);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  transition: var(--transition-normal);
}

.category-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 4px 16px rgba(0,0,0,0.15);
}

.category-card img {
  width: 100%;
  height: 180px;
  object-fit: cover;
}

.category-card-content {
  padding: 24px;
}

.category-card h3 {
  margin-bottom: 12px;
}

.category-card p {
  color: var(--text-muted);
  margin-bottom: 16px;
  font-size: 14px;
}

.category-card .btn {
  width: 100%;
  text-align: center;
}

/* ========================================
   Contact Page
   ======================================== */

.contact-page {
  padding: var(--section-padding);
}

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1.5fr;
  gap: 48px;
}

@media (max-width: 1024px) {
  .contact-grid {
    grid-template-columns: 1fr;
  }
}

.contact-info-cards {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.contact-card {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 24px;
  background-color: var(--light-gray);
  border-radius: 8px;
}

.contact-card .icon {
  font-size: 24px;
  color: var(--accent-red);
}

.contact-card h4 {
  margin-bottom: 8px;
  font-size: 16px;
}

.contact-card p {
  color: var(--text-muted);
  font-size: 14px;
}

.contact-card a {
  color: var(--primary-blue);
  text-decoration: none;
  font-weight: 600;
}

.contact-card a:hover {
  color: var(--accent-red);
}

/* 联系表单 */
.contact-form {
  background-color: var(--white);
  padding: 40px;
  border-radius: 8px;
  box-shadow: 0 2px 16px rgba(0,0,0,0.1);
}

.contact-form h3 {
  margin-bottom: 24px;
}

.form-group {
  margin-bottom: 24px;
}

.form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: 600;
  color: var(--text-dark);
}

.form-group label .required {
  color: var(--accent-red);
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 14px 16px;
  border: 1px solid #ddd;
  border-radius: 4px;
  font-size: 16px;
  font-family: inherit;
  transition: var(--transition-fast);
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--primary-blue);
  box-shadow: 0 0 0 3px rgba(10, 46, 92, 0.1);
}

.form-group textarea {
  resize: vertical;
  min-height: 150px;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

@media (max-width: 768px) {
  .form-row {
    grid-template-columns: 1fr;
  }
}

.form-message {
  padding: 16px;
  border-radius: 4px;
  margin-top: 16px;
  display: none;
}

.form-message.success {
  display: block;
  background-color: #d4edda;
  color: #155724;
  border: 1px solid #c3e6cb;
}

.form-message.error {
  display: block;
  background-color: #f8d7da;
  color: #721c24;
  border: 1px solid #f5c6cb;
}

/* ========================================
   底部固定联系栏（移动端）
   ======================================== */

.mobile-contact-bar {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background-color: var(--primary-blue);
  padding: 12px 16px;
  z-index: 999;
}

.mobile-contact-bar .container {
  display: flex;
  justify-content: space-around;
  gap: 12px;
}

.mobile-contact-bar a {
  flex: 1;
  text-align: center;
  padding: 12px;
  background-color: var(--accent-red);
  color: var(--white);
  text-decoration: none;
  border-radius: 4px;
  font-weight: 600;
  font-size: 14px;
  transition: var(--transition-fast);
}

.mobile-contact-bar a:hover {
  background-color: #a01830;
}

@media (max-width: 768px) {
  .mobile-contact-bar {
    display: block;
  }
  
  body {
    padding-bottom: 60px;
  }
}

/* ========================================
   图片懒加载动画
   ======================================== */

img[data-src] {
  opacity: 0;
  transition: opacity 0.3s ease-in;
}

img.loaded {
  opacity: 1;
}

/* ========================================
   表单 Loading 状态
   ======================================== */

.btn.loading {
  position: relative;
  color: transparent;
  pointer-events: none;
}

.btn.loading::after {
  content: '';
  position: absolute;
  width: 20px;
  height: 20px;
  top: 50%;
  left: 50%;
  margin-left: -10px;
  margin-top: -10px;
  border: 2px solid rgba(255,255,255,0.3);
  border-top-color: var(--white);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}