/* ============================================
   LIKUN AI LAB - Main Stylesheet
   技术栈: 纯 HTML + CSS + JS
   风格: 红色白色 AI 科技公司
   ============================================ */

/* ---------- CSS 变量 ---------- */
:root {
  --primary: #E60012;
  --primary-dark: #C0000F;
  --primary-light: #FF4D5A;
  --secondary: #0A0A0A;
  --text: #1A1A1A;
  --text-light: #666666;
  --text-lighter: #999999;
  --bg: #FFFFFF;
  --bg-light: #F8F9FA;
  --bg-gray: #F0F0F0;
  --border: #E5E5E5;
  --shadow: 0 4px 20px rgba(0,0,0,0.08);
  --shadow-hover: 0 8px 30px rgba(230,0,18,0.15);
  --radius: 12px;
  --radius-sm: 8px;
  --transition: all 0.3s ease;
  --max-width: 1200px;
  --nav-height: 72px;
}

/* ---------- 全局重置 ---------- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: inherit;
  text-decoration: none;
  transition: var(--transition);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

ul, ol {
  list-style: none;
}

/* ---------- 布局工具 ---------- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 100px 0;
}

.section-header {
  text-align: center;
  margin-bottom: 60px;
}

.section-header h2 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--secondary);
}

.section-header p {
  font-size: 1.125rem;
  color: var(--text-light);
  max-width: 600px;
  margin: 0 auto;
}

/* ---------- 导航栏 ---------- */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  z-index: 1000;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid transparent;
  transition: var(--transition);
}

.navbar.scrolled {
  border-bottom-color: var(--border);
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

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

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--secondary);
}

.logo-img {
  height: 40px;
  width: auto;
  border-radius: 50%;
  display: block;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 36px;
}

.nav-menu a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text);
  position: relative;
  padding: 4px 0;
}

.nav-menu a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary);
  transition: var(--transition);
}

.nav-menu a:hover,
.nav-menu a.active {
  color: var(--primary);
}

.nav-menu a:hover::after,
.nav-menu a.active::after {
  width: 100%;
}

.nav-cta {
  background: var(--primary);
  color: white !important;
  padding: 10px 24px !important;
  border-radius: 100px;
  font-weight: 600;
}

.nav-cta::after {
  display: none !important;
}

.nav-cta:hover {
  background: var(--primary-dark);
  transform: translateY(-1px);
}

/* 汉堡菜单 */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--secondary);
  transition: var(--transition);
  border-radius: 2px;
}

.hamburger.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.hamburger.active span:nth-child(2) {
  opacity: 0;
}

.hamburger.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 32px;
  font-size: 1rem;
  font-weight: 600;
  border-radius: 100px;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  font-family: inherit;
}

.btn-primary {
  background: var(--primary);
  color: white;
  box-shadow: 0 4px 15px rgba(230,0,18,0.3);
}

.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(230,0,18,0.4);
}

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

.btn-outline:hover {
  background: var(--primary);
  color: white;
  transform: translateY(-2px);
}

.btn-white {
  background: white;
  color: var(--primary);
  box-shadow: var(--shadow);
}

.btn-white:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

.btn-lg {
  padding: 16px 40px;
  font-size: 1.125rem;
}

/* ---------- Hero / Banner ---------- */
.hero {
  min-height: 80vh;
  display: flex;
  align-items: center;
  background: linear-gradient(135deg, var(--secondary) 0%, #1a1a2e 50%, var(--secondary) 100%);
  position: relative;
  overflow: hidden;
  padding-top: var(--nav-height);
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 800px;
  height: 800px;
  background: radial-gradient(circle, rgba(230,0,18,0.15) 0%, transparent 70%);
  border-radius: 50%;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -30%;
  left: -10%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(230,0,18,0.1) 0%, transparent 70%);
  border-radius: 50%;
}

.hero .container {
  position: relative;
  z-index: 1;
}

.hero-content {
  max-width: 800px;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1.2;
  color: white;
  margin-bottom: 24px;
  white-space: nowrap;
}

.hero h1 span {
  color: var(--primary);
}

.hero p {
  font-size: 1.25rem;
  color: rgba(255,255,255,0.7);
  margin-bottom: 40px;
  line-height: 1.7;
  max-width: 640px;
}

.hero-buttons {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

/* ---------- 卡片 ---------- */
.card {
  background: var(--bg);
  border-radius: var(--radius);
  padding: 40px;
  border: 1px solid var(--border);
  transition: var(--transition);
}

.card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-hover);
  transform: translateY(-4px);
}

.card-icon {
  width: 56px;
  height: 56px;
  background: rgba(230,0,18,0.1);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 24px;
  color: var(--primary);
  font-size: 1.5rem;
}

.card h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--secondary);
}

.card p {
  color: var(--text-light);
  font-size: 0.9375rem;
  line-height: 1.7;
}

/* ---------- 网格布局 ---------- */
.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

/* ---------- 数据展示 ---------- */
.stats-section {
  background: var(--bg-light);
}

.stat-card {
  text-align: center;
  padding: 48px 32px;
  background: var(--bg);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  transition: var(--transition);
}

.stat-card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-hover);
}

.stat-card .icon {
  width: 64px;
  height: 64px;
  background: rgba(230,0,18,0.1);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px;
  color: var(--primary);
  font-size: 1.75rem;
}

.stat-card .number {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 8px;
}

.stat-card .label {
  font-size: 1rem;
  color: var(--text-light);
}

/* ---------- 文章卡片 ---------- */
.article-card {
  background: var(--bg);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  overflow: hidden;
  transition: var(--transition);
}

.article-card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-hover);
  transform: translateY(-4px);
}

.article-card .article-body {
  padding: 28px;
}

.article-card .tag {
  display: inline-block;
  background: rgba(230,0,18,0.1);
  color: var(--primary);
  padding: 4px 12px;
  border-radius: 100px;
  font-size: 0.75rem;
  font-weight: 600;
  margin-bottom: 12px;
}

.article-card h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--secondary);
  line-height: 1.4;
}

.article-title-link {
  color: var(--secondary);
}

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

.article-card:hover .article-title-link {
  color: var(--primary);
}

.article-card p {
  color: var(--text-light);
  font-size: 0.9375rem;
  line-height: 1.7;
  margin-bottom: 16px;
}

.article-card .meta {
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 0.875rem;
  color: var(--text-lighter);
}

/* ---------- 岗位卡片 ---------- */
.job-card {
  background: var(--bg);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 32px;
  transition: var(--transition);
}

.job-card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-hover);
}

.job-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 16px;
}

.job-header h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--secondary);
}

.job-tags {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
}

.job-tag {
  background: var(--bg-light);
  color: var(--text-light);
  padding: 4px 12px;
  border-radius: 100px;
  font-size: 0.8125rem;
}

.job-desc {
  color: var(--text-light);
  font-size: 0.9375rem;
  line-height: 1.7;
  margin-bottom: 20px;
}

.job-details {
  display: none;
  padding-top: 20px;
  margin-top: 20px;
  border-top: 1px solid var(--border);
}

.job-details.open {
  display: block;
}

.job-details h4 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--secondary);
}

.job-details ul {
  margin-bottom: 16px;
  padding-left: 20px;
}

.job-details ul li {
  list-style: disc;
  color: var(--text-light);
  font-size: 0.9375rem;
  line-height: 1.8;
}

.toggle-btn {
  background: none;
  border: none;
  color: var(--primary);
  font-weight: 600;
  cursor: pointer;
  font-size: 0.9375rem;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: inherit;
}

.toggle-btn:hover {
  color: var(--primary-dark);
}

/* ---------- 时间线 ---------- */
.timeline {
  position: relative;
  padding-left: 40px;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--border);
}

.timeline-item {
  position: relative;
  padding-bottom: 40px;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -36px;
  top: 4px;
  width: 16px;
  height: 16px;
  background: var(--primary);
  border-radius: 50%;
  border: 3px solid var(--bg);
  box-shadow: 0 0 0 2px var(--primary);
}

.timeline-item .year {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--primary);
  margin-bottom: 8px;
}

.timeline-item h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--secondary);
}

.timeline-item p {
  color: var(--text-light);
  font-size: 0.9375rem;
  line-height: 1.7;
}

/* ---------- 联系表单 ---------- */
.form-group {
  margin-bottom: 24px;
}

.form-group label {
  display: block;
  font-size: 0.9375rem;
  font-weight: 500;
  margin-bottom: 8px;
  color: var(--secondary);
}

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

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 14px 18px;
  font-size: 1rem;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg);
  color: var(--text);
  font-family: inherit;
  transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(230,0,18,0.1);
}

.form-group input.error,
.form-group textarea.error {
  border-color: var(--primary);
}

.error-msg {
  color: var(--primary);
  font-size: 0.875rem;
  margin-top: 6px;
  display: none;
}

.error-msg.show {
  display: block;
}

.form-group textarea {
  min-height: 140px;
  resize: vertical;
}

.form-success {
  display: none;
  background: rgba(230,0,18,0.05);
  border: 1px solid rgba(230,0,18,0.2);
  color: var(--primary);
  padding: 16px 20px;
  border-radius: var(--radius-sm);
  margin-bottom: 24px;
  font-weight: 500;
}

.form-success.show {
  display: block;
}

/* ---------- 联系信息卡片 ---------- */
.contact-info-card {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 24px;
  background: var(--bg-light);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  transition: var(--transition);
}

.contact-info-card:hover {
  border-color: var(--primary);
}

.contact-info-card .icon {
  width: 48px;
  height: 48px;
  background: rgba(230,0,18,0.1);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  font-size: 1.25rem;
  flex-shrink: 0;
}

.contact-info-card h4 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--secondary);
}

.contact-info-card p,
.contact-info-card a {
  font-size: 0.9375rem;
  color: var(--text-light);
}

.contact-info-card a:hover {
  color: var(--primary);
}

/* ---------- CTA 区域 ---------- */
.cta-section {
  background: linear-gradient(135deg, var(--secondary) 0%, #1a1a2e 100%);
  text-align: center;
  color: white;
}

.cta-section h2 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 16px;
}

.cta-section p {
  font-size: 1.125rem;
  color: rgba(255,255,255,0.7);
  margin-bottom: 32px;
  max-width: 500px;
  margin-left: auto;
  margin-right: auto;
}

/* ---------- Footer ---------- */
.footer {
  background: var(--secondary);
  color: rgba(255,255,255,0.6);
  padding: 60px 0 24px;
}

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

.footer-brand .logo {
  color: white;
  margin-bottom: 16px;
}

.footer-brand p {
  font-size: 0.9375rem;
  line-height: 1.7;
  max-width: 300px;
}

.footer-col h4 {
  color: white;
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 20px;
}

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

.footer-col ul li a {
  font-size: 0.9375rem;
  color: rgba(255,255,255,0.6);
}

.footer-col ul li a:hover {
  color: var(--primary-light);
}

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.875rem;
}

.footer-bottom a {
  color: rgba(255,255,255,0.6);
}

.footer-bottom a:hover {
  color: var(--primary-light);
}

/* ---------- 页面标题区域 ---------- */
.page-header {
  background: linear-gradient(135deg, var(--secondary) 0%, #1a1a2e 100%);
  padding: 160px 0 80px;
  text-align: center;
  color: white;
}

.page-header h1 {
  font-size: 3rem;
  font-weight: 700;
  margin-bottom: 16px;
}

.page-header p {
  font-size: 1.125rem;
  color: rgba(255,255,255,0.7);
  max-width: 600px;
  margin: 0 auto;
}

/* ---------- 锚点导航 ---------- */
.anchor-nav {
  position: sticky;
  top: var(--nav-height);
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  z-index: 100;
  padding: 16px 0;
}

.anchor-nav .container {
  display: flex;
  gap: 32px;
  justify-content: center;
}

.anchor-nav a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-light);
  padding: 8px 0;
  border-bottom: 2px solid transparent;
  transition: var(--transition);
}

.anchor-nav a:hover,
.anchor-nav a.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

/* ---------- 服务详情区块 ---------- */
.service-section {
  padding: 80px 0;
}

.service-section:nth-child(even) {
  background: var(--bg-light);
}

.service-section .container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
}

.service-section.reverse .container {
  direction: rtl;
}

.service-section.reverse .container > * {
  direction: ltr;
}

.service-content .tag {
  display: inline-block;
  background: rgba(230,0,18,0.1);
  color: var(--primary);
  padding: 6px 16px;
  border-radius: 100px;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 20px;
}

.service-content h2 {
  font-size: 2.25rem;
  font-weight: 700;
  margin-bottom: 20px;
  color: var(--secondary);
}

.service-content > p {
  font-size: 1.0625rem;
  color: var(--text-light);
  line-height: 1.8;
  margin-bottom: 28px;
}

.service-features {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.service-feature {
  display: flex;
  align-items: flex-start;
  gap: 12px;
}

.service-feature .check {
  width: 24px;
  height: 24px;
  background: rgba(230,0,18,0.1);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  font-size: 0.75rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.service-feature p {
  font-size: 0.9375rem;
  color: var(--text);
  line-height: 1.6;
}

.service-visual {
  background: linear-gradient(135deg, rgba(230,0,18,0.05) 0%, rgba(230,0,18,0.1) 100%);
  border-radius: var(--radius);
  padding: 60px 40px;
  text-align: center;
  border: 1px solid rgba(230,0,18,0.15);
}

.service-visual .icon-large {
  width: 100px;
  height: 100px;
  background: rgba(230,0,18,0.1);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 24px;
  color: var(--primary);
  font-size: 2.5rem;
}

.service-visual h3 {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--secondary);
  margin-bottom: 12px;
}

.service-visual p {
  color: var(--text-light);
  font-size: 1rem;
}

/* ---------- 分类筛选 ---------- */
.filter-tabs {
  display: flex;
  gap: 12px;
  justify-content: center;
  margin-bottom: 48px;
  flex-wrap: wrap;
}

.filter-tab {
  padding: 10px 24px;
  border-radius: 100px;
  border: 1.5px solid var(--border);
  background: var(--bg);
  color: var(--text-light);
  font-size: 0.9375rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  font-family: inherit;
}

.filter-tab:hover,
.filter-tab.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

/* ---------- 复制提示 ---------- */
.copy-toast {
  position: fixed;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--secondary);
  color: white;
  padding: 12px 24px;
  border-radius: 100px;
  font-size: 0.9375rem;
  font-weight: 500;
  z-index: 9999;
  opacity: 0;
  transition: all 0.3s ease;
  pointer-events: none;
}

.copy-toast.show {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
}

/* ---------- 动画 ---------- */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ---------- 响应式 ---------- */
@media (max-width: 1023px) {
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }

  .service-section .container {
    gap: 40px;
  }
}

@media (max-width: 767px) {
  :root {
    --nav-height: 64px;
  }

  .section {
    padding: 60px 0;
  }

  .section-header h2 {
    font-size: 1.75rem;
  }

  .section-header p {
    font-size: 1rem;
  }

  .grid-3,
  .grid-2,
  .grid-4 {
    grid-template-columns: 1fr;
  }

  .hero h1 {
    font-size: 2.25rem;
    white-space: normal;
  }

  .hero p {
    font-size: 1rem;
  }

  .page-header {
    padding: 120px 0 60px;
  }

  .page-header h1 {
    font-size: 2rem;
  }

  .nav-menu {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--bg);
    flex-direction: column;
    padding: 24px;
    gap: 0;
    border-bottom: 1px solid var(--border);
    transform: translateY(-150%);
    opacity: 0;
    transition: all 0.3s ease;
    pointer-events: none;
  }

  .nav-menu.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: all;
  }

  .nav-menu a {
    padding: 14px 0;
    border-bottom: 1px solid var(--border);
    width: 100%;
    text-align: center;
  }

  .nav-menu a:last-child {
    border-bottom: none;
  }

  .hamburger {
    display: flex;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .footer-bottom {
    flex-direction: column;
    gap: 12px;
    text-align: center;
  }

  .service-section .container {
    grid-template-columns: 1fr;
  }

  .service-section.reverse .container {
    direction: ltr;
  }

  .anchor-nav .container {
    gap: 16px;
    flex-wrap: wrap;
  }

  .cta-section h2 {
    font-size: 1.75rem;
  }

  .card {
    padding: 28px;
  }

  .stat-card .number {
    font-size: 2rem;
  }
}

/* ---------- 打印优化 ---------- */
@media print {
  .navbar,
  .hamburger,
  .anchor-nav,
  .copy-toast {
    display: none !important;
  }

  .hero {
    min-height: auto;
    padding: 40px 0;
  }
}