/* ===================================
    CSS Variables - 全站变量
   =================================== */
:root {
  /* 主色调 */
  --color-primary: #4F46E5;
  --color-primary-hover: #4338CA;
  --color-primary-light: #EEF2FF;
  --color-secondary: #3B82F6;
  --color-secondary-hover: #2563EB;

  /* 文字颜色 */
  --color-text-heading: #111827;
  --color-text-body: #374151;
  --color-text-secondary: #6B7280;
  --color-text-muted: #9CA3AF;

  /* 边框与分割 */
  --color-border: #E5E7EB;
  --color-border-light: #F3F4F6;
  --color-border-hover: #D1D5DB;

  /* 背景色 */
  --color-bg-primary: #FFFFFF;
  --color-bg-secondary: #F8F9FA;
  --color-bg-tertiary: #F3F4F6;
  --color-bg-card: #FFFFFF;

  /* 链接与交互 */
  --color-link: #4F46E5;
  --color-link-hover: #4338CA;

  /* 覆盖层 */
  --color-overlay-dark: rgba(17, 24, 39, 0.6);

  /* 标签/徽章背景 */
  --color-tag-bg: #EEF2FF;
  --color-tag-bg-hover: #E0E7FF;

  /* 社交媒体颜色 */
  --color-social-facebook: #1877F2;
  --color-social-twitter: #1DA1F2;
  --color-social-linkedin: #0A66C2;
  --color-social-whatsapp: #25D366;
  --color-social-pinterest: #E60023;
  --color-social-email: #6B7280;

  /* 圆角/阴影/过渡 */
  --radius-sm: 4px;
  --radius-md: 8px;
  --shadow-soft: 0 4px 6px -1px rgba(0,0,0,0.05), 0 2px 4px -1px rgba(0,0,0,0.03);
  --shadow-hover: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -2px rgba(0,0,0,0.04);
  --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===================================
    Base - 基础重置与排版
   =================================== */
* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  color: var(--color-text-heading);
  background-color: var(--color-bg-primary);
  line-height: 1.6;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--color-text-heading);
}
h1 { font-size: 3.5rem; }
h2 { font-size: 2.25rem; margin-bottom: 1rem; }
h3 { font-size: 1.25rem; }
p { color: var(--color-text-secondary); }
a { color: var(--color-link); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ===================================
    Layout - 布局
   =================================== */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section-py { padding: 5rem 0; }
.bg-alt { background-color: var(--color-bg-secondary); }

/* ===================================
    Buttons - 按钮
   =================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  font-weight: 500;
  font-size: 1rem;
  border-radius: var(--radius-sm);
  transition: var(--transition);
  cursor: pointer;
  border: none;
  text-decoration: none;
  gap: 0.5rem;
}

.btn-primary {
  background-color: var(--color-primary);
  color: #fff;
}
.btn-primary:hover {
  background-color: var(--color-primary-hover);
  text-decoration: none;
  transform: translateY(-1px);
}

.btn-outline {
  border: 1px solid var(--color-border);
  background: #fff;
  color: var(--color-text-heading);
}
.btn-outline:hover {
  border-color: var(--color-border-hover);
  background: var(--color-bg-secondary);
  text-decoration: none;
}

/* ===================================
    Card - 卡片
   =================================== */
.card {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  box-shadow: var(--shadow-soft);
  transition: var(--transition);
}
.card:hover {
  box-shadow: var(--shadow-hover);
  border-color: var(--color-border-hover);
}

/* ===================================
    Hero - 顶部
   =================================== */
.hero {
  padding: 6rem 0 4rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.hero-bg-parallax {
  position: absolute;
  top: -10%;
  left: 0;
  width: 100%;
  height: 120%;
  background: radial-gradient(circle at center, var(--color-primary-light) 0%, transparent 70%);
  z-index: -1;
  opacity: 0.5;
}
.hero h1 { margin-bottom: 1.25rem; }
.hero .subtitle {
  font-size: 1.25rem;
  max-width: 800px;
  margin: 0 auto 2rem;
}
.hero-cta {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-bottom: 3rem;
}

.trust-badges {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  flex-wrap: wrap;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  font-weight: 500;
}
.trust-badges span {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.trust-badges i { color: var(--color-primary); }

/* ===================================
    Live Tool - 工具区
   =================================== */
.tool-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  align-items: start;
}
.tool-panel { padding: 2rem; }

.form-group { margin-bottom: 1.5rem; }
.form-label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.5rem;
  font-size: 0.875rem;
}
.form-control {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-family: 'Inter', sans-serif;
  font-size: 0.875rem;
  transition: var(--transition);
  outline: none;
  background: #fff;
  color: var(--color-text-heading);
}
.form-control:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-light);
}

.format-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.75rem;
}
.format-btn {
  border: 1px solid var(--color-border);
  background: #fff;
  border-radius: var(--radius-sm);
  padding: 0.75rem 0.5rem;
  text-align: center;
  cursor: pointer;
  font-size: 0.875rem;
  transition: var(--transition);
  color: var(--color-text-heading);
  font-weight: 500;
}
.format-btn:hover {
  border-color: var(--color-primary);
  background: var(--color-primary-light);
  color: var(--color-primary);
}
.format-btn.active {
  border-color: var(--color-primary);
  background: var(--color-primary);
  color: #fff;
}

.options-flex {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  margin-top: 1rem;
}
.checkbox-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  cursor: pointer;
}

.preview-panel {
  background: var(--color-bg-secondary);
  border-radius: var(--radius-md);
  padding: 2rem;
  border: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  align-items: center;
}
.pdf-preview-box {
  background: #fff;
  width: 100%;
  aspect-ratio: 8.5 / 11;
  box-shadow: var(--shadow-hover);
  border: 1px solid #ddd;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.5rem;
}
.pdf-preview-box img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.8;
}

/* ===================================
    Format Showcase - 题型展示
   =================================== */
.showcase-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 3rem;
}
.showcase-card { padding: 0; overflow: hidden; }
.showcase-card img {
  width: 100%;
  height: 200px;
  object-fit: cover;
  border-bottom: 1px solid var(--color-border);
  border-radius: var(--radius-md) var(--radius-md) 0 0;
}
.showcase-card-body { padding: 1.5rem; }
.showcase-card h3 { font-size: 1.125rem; margin-bottom: 0.5rem; }
.showcase-card .tag {
  display: inline-block;
  padding: 0.25rem 0.5rem;
  background: var(--color-primary-light);
  color: var(--color-primary);
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 4px;
  margin-bottom: 1rem;
}

/* ===================================
    Word Libraries - 词库卡片
   =================================== */
.lib-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}
.lib-card { text-align: center; }
.lib-card h3 { font-size: 1rem; margin-bottom: 0.5rem; }
.lib-card p { font-size: 0.875rem; margin-bottom: 1rem; }

/* ===================================
    How It Works - 步骤
   =================================== */
.steps-flex {
  display: flex;
  justify-content: space-between;
  gap: 2rem;
  margin-top: 3rem;
  position: relative;
}
.step-item {
  flex: 1;
  text-align: center;
  position: relative;
  z-index: 1;
}
.step-number {
  width: 48px;
  height: 48px;
  background: var(--color-primary);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  font-weight: 700;
  margin: 0 auto 1rem;
}
.step-line {
  position: absolute;
  top: 24px;
  left: 15%;
  right: 15%;
  height: 2px;
  background: var(--color-border);
  z-index: 0;
}

/* ===================================
    Use Cases / Why Us - 列表网格
   =================================== */
.list-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}
.list-item {
  display: flex;
  gap: 1rem;
  align-items: flex-start;
}
.list-item i {
  color: var(--color-primary);
  font-size: 1.25rem;
  margin-top: 0.25rem;
}

/* ===================================
    FAQ - 折叠
   =================================== */
.faq-list { max-width: 800px; margin: 3rem auto 0; }
.faq-item {
  border-bottom: 1px solid var(--color-border);
  padding: 1.5rem 0;
  cursor: pointer;
}
.faq-question {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
  font-size: 1.125rem;
}
.faq-question i {
  transition: transform 0.3s;
  color: var(--color-text-secondary);
}
.faq-answer {
  margin-top: 1rem;
  display: none;
  color: var(--color-text-secondary);
}
.faq-item.active .faq-answer { display: block; }
.faq-item.active .faq-question i { transform: rotate(180deg); }

/* ===================================
    Footer / SEO Content
   =================================== */
.tool-footer {
  background: var(--color-bg-secondary);
  padding: 4rem 0 2rem;
  border-top: 1px solid var(--color-border);
}
.seo-content {
  max-width: 800px;
  margin: 0 auto 3rem;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}
.footer-links {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-top: 2rem;
  border-top: 1px solid var(--color-border);
  padding-top: 2rem;
  font-size: 0.875rem;
}

/* ===================================
    Scroll Progress
   =================================== */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 4px;
  background: var(--color-primary);
  width: 0%;
  z-index: 9999;
  transform-origin: left;
}

/* ===================================
    Responsive
   =================================== */
@media (max-width: 768px) {
  h1 { font-size: 2.5rem; }
  .tool-grid { grid-template-columns: 1fr; }
  .format-grid { grid-template-columns: 1fr 1fr; }
  .steps-flex { flex-direction: column; }
  .step-line { display: none; }
}