/* CSS Variables for Design System */
:root {
  /* Color Palette */
  --primary-color: #4A90E2;        /*宁静的蓝色 - Calm Blue*/
  --secondary-color: #50E3C2;      /*清新的绿色 - Fresh Green*/
  --accent-color: #F8B71C;         /*温和的金色 - Warm Gold*/
  --background-color: #F4F4F4;     /*温暖的米白/浅灰 - Light Background*/
  --text-primary: #333333;         /*深文本颜色*/
  --text-secondary: #666666;       /*浅文本颜色*/
  --white: #FFFFFF;                /*纯白色*/
  --light-gray: #F0F0F0;           /*浅灰色*/
  --border-color: #E0E0E0;         /*边框颜色*/
  
  /* Typography */
  --font-title: "Lora", serif;     /*标题字体 - 优雅的衬线字体*/
  --font-body: "Nunito", sans-serif; /*正文字体 - 高可读性无衬线字体*/
  --font-size-small: 0.875rem;     /*小字体*/
  --font-size-base: 1rem;          /*基础字体*/
  --font-size-large: 1.25rem;      /*大字体*/
  --font-size-xl: 1.5rem;          /*超大字体*/
  --font-size-xxl: 2rem;           /*特大字体*/
  --font-size-xxxl: 2.5rem;        /*巨大字体*/
  --font-weight-light: 300;        /*细体*/
  --font-weight-regular: 400;      /*常规*/
  --font-weight-semibold: 600;     /*半粗体*/
  --font-weight-bold: 700;         /*粗体*/
  
  /* Spacing */
  --spacing-xs: 0.5rem;            /*超小间距*/
  --spacing-sm: 1rem;              /*小间距*/
  --spacing-md: 1.5rem;            /*中间距*/
  --spacing-lg: 2rem;              /*大间距*/
  --spacing-xl: 3rem;              /*超大间距*/
  
  /* Border Radius */
  --border-radius-sm: 4px;         /*小圆角*/
  --border-radius-md: 8px;         /*中圆角*/
  --border-radius-lg: 12px;        /*大圆角*/
  --border-radius-xl: 20px;        /*超大圆角*/
  
  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.1);
  
  /* Transitions */
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-weight: var(--font-weight-regular);
  color: var(--text-primary);
  background-color: var(--background-color);
  line-height: 1.6;
}

/* Container */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-title);
  font-weight: var(--font-weight-bold);
  line-height: 1.2;
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

h1 {
  font-size: var(--font-size-xxxl);
}

h2 {
  font-size: var(--font-size-xxl);
}

h3 {
  font-size: var(--font-size-xl);
}

p {
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-sm);
}

.section-title {
  text-align: center;
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

.section-subtitle {
  text-align: center;
  font-size: var(--font-size-large);
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto var(--spacing-xl);
}

/* Header Styles */
.header {
  background-color: var(--white);
  box-shadow: var(--shadow-sm);
  position: fixed;
  width: 100%;
  top: 0;
  z-index: 1000;
}

.navbar {
  padding: var(--spacing-sm) 0;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.logo h2 {
  color: var(--primary-color);
  font-family: var(--font-title);
  font-weight: var(--font-weight-bold);
}

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

.nav-list li {
  margin-left: var(--spacing-lg);
}

.nav-list a {
  text-decoration: none;
  color: var(--text-primary);
  font-weight: var(--font-weight-semibold);
  transition: var(--transition-fast);
}

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

.hamburger {
  display: none;
  flex-direction: column;
  cursor: pointer;
}

.bar {
  width: 25px;
  height: 3px;
  background-color: var(--text-primary);
  margin: 3px 0;
  transition: var(--transition-fast);
}

/* Hero Section */
.hero {
  padding: 120px var(--spacing-md) var(--spacing-xl) var(--spacing-md);
  background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100" viewBox="0 0 100 100"><rect width="100" height="100" fill="none" stroke="%234A90E2" stroke-width="0.5" opacity="0.1"/></svg>');
  opacity: 0.1;
}

.hero-content {
  max-width: 700px;
  margin: 0 auto;
  text-align: center;
  position: relative;
  z-index: 1;
}

.hero-title {
  font-size: var(--font-size-xxxl);
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
  animation: fadeInUp 1s ease;
}

.hero-subtitle {
  font-size: var(--font-size-large);
  margin-bottom: var(--spacing-xl);
  color: var(--text-secondary);
  animation: fadeInUp 1s ease 0.2s both;
}

/* Download Buttons */
.download-section {
  margin: var(--spacing-xl) 0;
}

.download-buttons {
  display: flex;
  justify-content: center;
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

.download-btn {
  display: block;
  text-decoration: none;
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  transition: var(--transition-normal);
  box-shadow: var(--shadow-md);
  min-width: 220px;
  animation: fadeInUp 1s ease 0.4s both;
}

.download-btn:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.download-btn.app-store {
  background-color: #000000;
}

.download-btn.google-play {
  background-color: var(--white);
  border: 1px solid var(--border-color);
}

.btn-content {
  display: flex;
  align-items: center;
  padding: var(--spacing-sm);
}

.btn-icon {
  margin-right: var(--spacing-sm);
}

.btn-text p {
  font-size: var(--font-size-small);
  font-weight: var(--font-weight-semibold);
  color: var(--text-secondary);
  margin: 0;
}

.btn-text h3 {
  font-size: var(--font-size-large);
  font-weight: var(--font-weight-bold);
  color: var(--white);
  margin: 0;
}

.google-play .btn-text h3 {
  color: var(--text-primary);
}

/* Features Section */
.features {
  padding: var(--spacing-xl) var(--spacing-md);
  background-color: var(--white);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-lg);
  margin-top: var(--spacing-xl);
}

.feature-card {
  background: var(--white);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-lg);
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: var(--transition-normal);
  opacity: 0;
  transform: translateY(20px);
  animation: fadeInUp 0.6s ease forwards;
}

.feature-card:nth-child(1) {
  animation-delay: 0.2s;
}

.feature-card:nth-child(2) {
  animation-delay: 0.4s;
}

.feature-card:nth-child(3) {
  animation-delay: 0.6s;
}

.feature-card:nth-child(4) {
  animation-delay: 0.8s;
}

.feature-card:hover {
  transform: translateY(-10px);
  box-shadow: var(--shadow-md);
}

.feature-icon {
  margin: 0 auto var(--spacing-md);
  width: 80px;
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: rgba(74, 144, 226, 0.1);
  border-radius: 50%;
}

.feature-card h3 {
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

.feature-card p {
  color: var(--text-secondary);
}

/* Preview Section */
.preview {
  padding: var(--spacing-xl) var(--spacing-md);
  background-color: var(--background-color);
}

.preview-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-lg);
  margin-top: var(--spacing-xl);
}

.mockup-container {
  display: flex;
  justify-content: center;
  margin-bottom: var(--spacing-sm);
}

.phone-mockup {
  position: relative;
  width: 200px;
  height: 400px;
  background: var(--white);
  border-radius: 30px;
  box-shadow: var(--shadow-md);
  border: 12px solid #1e1f22;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.phone-mockup::before {
  content: "";
  position: absolute;
  top: -30px;
  left: 50%;
  transform: translateX(-50%);
  width: 40px;
  height: 5px;
  background: #1e1f22;
  border-radius: 5px;
}

.phone-mockup::after {
  content: "";
  position: absolute;
  bottom: 15px;
  left: 50%;
  transform: translateX(-50%);
  width: 50px;
  height: 50px;
  border: 3px solid #1e1f22;
  border-radius: 50%;
}

.screen-content {
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: var(--font-weight-semibold);
  text-align: center;
  padding: var(--spacing-md);
  position: relative;
  overflow: hidden;
}

.screen-content::before {
  content: "";
  position: absolute;
  top: 20px;
  left: 20px;
  right: 20px;
  height: 20px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 4px;
}

.screen-content::after {
  content: "";
  position: absolute;
  top: 50px;
  left: 20px;
  right: 20px;
  height: 100px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 4px;
}

.preview-item p {
  text-align: center;
  color: var(--text-secondary);
  font-weight: var(--font-weight-semibold);
}

/* CTA Section */
.cta {
  padding: var(--spacing-xl) var(--spacing-md);
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  color: var(--white);
  text-align: center;
}

.cta .section-title {
  color: var(--white);
}

.cta .section-subtitle {
  color: rgba(255, 255, 255, 0.9);
}

.cta-download .download-btn:hover {
  transform: translateY(-5px);
}

.cta-download .download-btn.app-store {
  background-color: #000000;
}

.cta-download .download-btn.google-play {
  background-color: var(--white);
  border: 1px solid var(--border-color);
}

.cta-download .google-play .btn-text h3 {
  color: var(--text-primary);
}

/* Footer */
.footer {
  background-color: var(--white);
  padding: var(--spacing-lg) var(--spacing-md);
  text-align: center;
  border-top: 1px solid var(--border-color);
}

.footer p {
  margin-bottom: var(--spacing-sm);
  color: var(--text-secondary);
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--spacing-lg);
}

.footer-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: var(--font-size-small);
  transition: var(--transition-fast);
}

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

/* Animations */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Responsive Design */
@media (max-width: 768px) {
  h1 {
    font-size: var(--font-size-xxl);
  }
  
  h2 {
    font-size: var(--font-size-xl);
  }
  
  .nav-list {
    position: fixed;
    top: 70px;
    left: -100%;
    width: 100%;
    height: calc(100vh - 70px);
    background-color: var(--white);
    flex-direction: column;
    align-items: center;
    padding-top: var(--spacing-xl);
    transition: var(--transition-normal);
  }
  
  .nav-list.active {
    left: 0;
  }
  
  .nav-list li {
    margin: var(--spacing-md) 0;
  }
  
  .hamburger {
    display: flex;
  }
  
  .hero {
    padding: 100px var(--spacing-md) var(--spacing-lg) var(--spacing-md);
  }
  
  .download-buttons {
    flex-direction: column;
    align-items: center;
  }
  
  .download-btn {
    width: 100%;
    max-width: 300px;
  }
  
  .features-grid {
    grid-template-columns: 1fr;
  }
  
  .preview-grid {
    grid-template-columns: 1fr;
  }
  
  .phone-mockup {
    width: 150px;
    height: 300px;
  }
  
  .footer-links {
    flex-direction: column;
    gap: var(--spacing-sm);
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--spacing-sm);
  }
  
  h1 {
    font-size: var(--font-size-xl);
  }
  
  .hero-title {
    font-size: var(--font-size-xxl);
  }
  
  .hero-subtitle {
    font-size: var(--font-size-base);
  }
  
  .section-subtitle {
    font-size: var(--font-size-base);
  }
  
  .btn-content {
    flex-direction: column;
    text-align: center;
  }
  
  .btn-text p {
    font-size: var(--font-size-small);
  }
  
  .btn-text h3 {
    font-size: var(--font-size-large);
  }
  
  .btn-icon {
    margin-right: 0;
    margin-bottom: var(--spacing-xs);
  }
}

/* Tablet Styles */
@media (min-width: 769px) and (max-width: 1024px) {
  .hero-title {
    font-size: 2rem;
  }
  
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Scroll animations */
.scroll-animate {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.scroll-animate.visible {
  opacity: 1;
  transform: translateY(0);
}