/* 基础变量与暗黑精美主题 */
:root {
  --bg-dark: #0a0d14;
  --bg-card: rgba(18, 24, 38, 0.75);
  --bg-card-hover: rgba(26, 35, 56, 0.85);
  --primary: #10b981;
  --primary-glow: rgba(16, 185, 129, 0.35);
  --primary-hover: #059669;
  --accent: #3b82f6;
  --text-main: #f3f4f6;
  --text-muted: #9ca3af;
  --border-color: rgba(255, 255, 255, 0.1);
  --border-glow: rgba(16, 185, 129, 0.4);
  --font-kai: "KaiTi", "STKaiti", "DFKai-SB", "楷体", serif;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-kai);
  background-color: var(--bg-dark);
  color: var(--text-main);
  line-height: 1.8;
  overflow-x: hidden;
  position: relative;
}

/* 全屏大图背景 + 遮罩 */
.bg-container {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: -2;
  background: url('bg.png') center/cover no-repeat fixed;
  filter: brightness(0.6) contrast(1.1);
}

.bg-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: -1;
  background: radial-gradient(circle at 50% 30%, rgba(10, 13, 20, 0.4) 0%, rgba(10, 13, 20, 0.85) 100%);
  pointer-events: none;
}

/* 动态光斑 */
.particle-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: -1;
  pointer-events: none;
}

/* 导航栏 */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 100;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background: rgba(10, 13, 20, 0.75);
  border-bottom: 1px solid var(--border-color);
  transition: all 0.3s ease;
}

.nav-container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.8rem;
  font-weight: 700;
  color: #fff;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  letter-spacing: 1px;
}

.logo span {
  color: var(--primary);
  text-shadow: 0 0 12px var(--primary-glow);
}

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
  align-items: center;
}

.nav-links a {
  color: var(--text-main);
  text-decoration: none;
  font-size: 1.15rem;
  transition: color 0.3s ease;
  position: relative;
}

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

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0%;
  height: 2px;
  background: var(--primary);
  transition: width 0.3s ease;
  box-shadow: 0 0 8px var(--primary);
}

.nav-links a:hover::after {
  width: 100%;
}

.btn-login {
  background: linear-gradient(135deg, var(--primary), var(--primary-hover));
  color: #fff !important;
  padding: 0.5rem 1.4rem;
  border-radius: 30px;
  font-weight: bold;
  box-shadow: 0 0 15px var(--primary-glow);
  transition: transform 0.3s ease, box-shadow 0.3s ease !important;
}

.btn-login:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 25px var(--primary-glow);
}

.btn-login::after {
  display: none !important;
}

/* 布局及章节 */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 2rem;
}

.hero {
  min-height: 90vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding-top: 6rem;
}

.hero-tag {
  display: inline-block;
  background: rgba(16, 185, 129, 0.15);
  border: 1px solid var(--primary);
  color: var(--primary);
  padding: 0.4rem 1.2rem;
  border-radius: 50px;
  font-size: 1rem;
  margin-bottom: 1.5rem;
  box-shadow: 0 0 15px var(--primary-glow);
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1.5rem;
  background: linear-gradient(180deg, #ffffff 0%, #d1d5db 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  font-size: 1.35rem;
  color: var(--text-muted);
  max-width: 800px;
  margin-bottom: 2.5rem;
}

.hero-btns {
  display: flex;
  gap: 1.5rem;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, #047857 100%);
  color: #fff;
  padding: 0.9rem 2.5rem;
  border-radius: 40px;
  text-decoration: none;
  font-size: 1.25rem;
  font-weight: bold;
  box-shadow: 0 4px 20px var(--primary-glow);
  transition: all 0.3s ease;
  display: inline-block;
}

.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 30px var(--primary-glow);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.9rem 2.5rem;
  border-radius: 40px;
  text-decoration: none;
  font-size: 1.25rem;
  transition: all 0.3s ease;
  backdrop-filter: blur(10px);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.3);
}

/* 通用Section */
.section {
  padding: 6rem 0;
}

.section-title {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 1rem;
  color: #fff;
}

.section-subtitle {
  text-align: center;
  font-size: 1.2rem;
  color: var(--text-muted);
  margin-bottom: 3.5rem;
}

/* 特性网格 */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2rem;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 2.2rem;
  backdrop-filter: blur(12px);
  transition: all 0.35 ease;
  position: relative;
  overflow: hidden;
}

.feature-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-glow);
  transform: translateY(-6px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5), 0 0 20px var(--primary-glow);
}

.feature-icon {
  font-size: 2.5rem;
  margin-bottom: 1.2rem;
  display: inline-block;
}

.feature-card h3 {
  font-size: 1.5rem;
  color: #fff;
  margin-bottom: 0.8rem;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 1.05rem;
  line-height: 1.7;
}

/* 订阅套餐 (VIP卡片) */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.price-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  padding: 2.5rem 2rem;
  text-align: center;
  backdrop-filter: blur(12px);
  position: relative;
  transition: all 0.35s ease;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.price-card.featured {
  border-color: var(--primary);
  box-shadow: 0 0 30px rgba(16, 185, 129, 0.25);
  transform: scale(1.03);
}

.price-card:hover {
  transform: translateY(-8px);
  border-color: var(--primary);
  box-shadow: 0 12px 35px rgba(0,0,0,0.6), 0 0 25px var(--primary-glow);
}

.badge-popular {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--primary);
  color: #000;
  font-size: 0.85rem;
  font-weight: bold;
  padding: 0.3rem 1.2rem;
  border-radius: 20px;
}

.price-card h3 {
  font-size: 1.8rem;
  color: #fff;
  margin-bottom: 0.5rem;
}

.price-sub {
  color: var(--text-muted);
  font-size: 1rem;
  margin-bottom: 1.5rem;
}

.price-num {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--primary);
  margin-bottom: 2rem;
}

.price-num span {
  font-size: 1.1rem;
  color: var(--text-muted);
  font-weight: normal;
}

.price-features {
  list-style: none;
  text-align: left;
  margin-bottom: 2rem;
}

.price-features li {
  padding: 0.6rem 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  color: #e5e7eb;
  font-size: 1.05rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.price-features li::before {
  content: "•";
  color: var(--primary);
  font-size: 1.5rem;
}

.btn-buy {
  display: block;
  width: 100%;
  padding: 0.85rem 0;
  border-radius: 30px;
  text-decoration: none;
  font-size: 1.15rem;
  font-weight: bold;
  transition: all 0.3s ease;
  border: 1px solid var(--primary);
  color: var(--primary);
  background: transparent;
}

.price-card.featured .btn-buy,
.btn-buy:hover {
  background: var(--primary);
  color: #000;
  box-shadow: 0 0 20px var(--primary-glow);
}

/* 文章知识库 */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 2rem;
  backdrop-filter: blur(12px);
  transition: all 0.35s ease;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.article-card:hover {
  border-color: var(--border-glow);
  transform: translateY(-5px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5), 0 0 15px var(--primary-glow);
}

.article-card h3 {
  font-size: 1.35rem;
  color: #fff;
  margin-bottom: 1rem;
  line-height: 1.5;
}

.article-card h3 a {
  color: inherit;
  text-decoration: none;
  transition: color 0.3s;
}

.article-card h3 a:hover {
  color: var(--primary);
}

.article-meta {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.article-excerpt {
  color: var(--text-muted);
  font-size: 1rem;
  margin-bottom: 1.5rem;
  line-height: 1.7;
}

.btn-readmore {
  color: var(--primary);
  text-decoration: none;
  font-weight: bold;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  transition: gap 0.3s ease;
}

.btn-readmore:hover {
  gap: 0.8rem;
}

/* 文章详情页专用样式 */
.article-detail {
  padding-top: 8rem;
  padding-bottom: 6rem;
}

.article-header {
  text-align: center;
  max-width: 900px;
  margin: 0 auto 3rem auto;
}

.article-header h1 {
  font-size: 2.6rem;
  color: #fff;
  margin-bottom: 1.5rem;
  line-height: 1.3;
}

.article-stats-bar {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  color: var(--text-muted);
  font-size: 1rem;
  padding: 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 50px;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.article-body {
  max-width: 900px;
  margin: 0 auto;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  padding: 3rem;
  backdrop-filter: blur(16px);
  font-size: 1.15rem;
  line-height: 2.1;
  color: #e5e7eb;
}

.article-body h2 {
  font-size: 1.8rem;
  color: var(--primary);
  margin: 2.5rem 0 1.2rem 0;
  border-bottom: 1px solid rgba(16, 185, 129, 0.3);
  padding-bottom: 0.5rem;
}

.article-body h3 {
  font-size: 1.4rem;
  color: #fff;
  margin: 1.8rem 0 1rem 0;
}

.article-body p {
  margin-bottom: 1.5rem;
  text-align: justify;
}

.article-body ul, .article-body ol {
  margin-bottom: 1.5rem;
  padding-left: 2rem;
}

.article-body li {
  margin-bottom: 0.5rem;
}

.article-cta-box {
  margin: 3rem 0;
  padding: 2rem;
  background: linear-gradient(135deg, rgba(16, 185, 129, 0.15), rgba(59, 130, 246, 0.15));
  border: 1px solid var(--primary);
  border-radius: 16px;
  text-align: center;
}

.article-cta-box h4 {
  font-size: 1.5rem;
  color: #fff;
  margin-bottom: 0.8rem;
}

.article-cta-box p {
  color: var(--text-muted);
  margin-bottom: 1.2rem;
}

/* FAQ 常见问题Accordion */
.faq-list {
  max-width: 900px;
  margin: 0 auto;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  margin-bottom: 1.2rem;
  overflow: hidden;
  backdrop-filter: blur(10px);
}

.faq-question {
  padding: 1.4rem 1.8rem;
  font-size: 1.25rem;
  font-weight: bold;
  color: #fff;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
}

.faq-question:hover {
  color: var(--primary);
}

.faq-answer {
  padding: 0 1.8rem 1.4rem 1.8rem;
  color: var(--text-muted);
  font-size: 1.05rem;
  line-height: 1.8;
  display: none;
}

.faq-item.active .faq-answer {
  display: block;
}

.faq-item.active .faq-toggle {
  transform: rotate(180deg);
}

.faq-toggle {
  transition: transform 0.3s ease;
  color: var(--primary);
}

/* 内部文章链接引导条 */
.internal-links-box {
  margin-top: 3rem;
  padding: 2rem;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border-color);
  border-radius: 16px;
}

.internal-links-box h4 {
  color: var(--primary);
  font-size: 1.3rem;
  margin-bottom: 1rem;
}

.internal-links-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
  list-style: none;
}

.internal-links-list li a {
  color: var(--text-main);
  text-decoration: none;
  transition: color 0.3s;
}

.internal-links-list li a:hover {
  color: var(--primary);
}

/* Footer 页脚 */
.footer {
  background: rgba(5, 7, 12, 0.95);
  border-top: 1px solid var(--border-color);
  padding: 4rem 0 2rem 0;
  margin-top: 6rem;
  color: var(--text-muted);
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2.5rem;
  margin-bottom: 3rem;
}

.footer-col h4 {
  color: #fff;
  font-size: 1.2rem;
  margin-bottom: 1.2rem;
}

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

.footer-col ul li {
  margin-bottom: 0.6rem;
}

.footer-col ul li a {
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.3s;
}

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

.footer-bottom {
  text-align: center;
  padding-top: 2rem;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  font-size: 0.95rem;
}

/* 响应式调整 */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2.2rem;
  }
  .nav-links {
    display: none; /* 可扩展移动端菜单 */
  }
  .article-body {
    padding: 1.5rem;
  }
}