/* ========================================
   BandSheet Website - Main Styles
   ======================================== */

/* CSS Variables - Theme Colors */
:root {
  /* Light Mode (Default) */
  --primary: #5C6B7A;
  --primary-dark: #44525E;
  --primary-light: #7A8E9E;
  --accent: #E88C3A;
  --accent-hover: #D47A2A;
  --success: #5A9E70;
  --warning: #C4922A;
  
  --bg-main: #F6F7F8;
  --bg-card: #FFFFFF;
  --bg-section-alt: #F0F2F4;
  --bg-code: #F3F4F6;
  
  --text-primary: #1A1A1A;
  --text-secondary: #6B7280;
  --text-tertiary: #9CA3AF;
  --text-inverse: #FFFFFF;
  
  --border: #E5E7EB;
  --border-light: #F3F4F6;
  
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.12);
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  
  --transition: 0.2s ease;
  --transition-slow: 0.3s ease;
}

/* Dark Mode */
[data-theme="dark"] {
  --primary: #7A8E9E;
  --primary-dark: #5C6B7A;
  --primary-light: #9AABB8;
  
  --bg-main: #111418;
  --bg-card: #1A1D22;
  --bg-section-alt: #151820;
  --bg-code: #1E2229;
  
  --text-primary: #F5F5F5;
  --text-secondary: #9CA3AF;
  --text-tertiary: #6B7280;
  
  --border: #2D3139;
  --border-light: #232730;
  
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.4);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.5);
}

/* ========================================
   Reset & Base
   ======================================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  background-color: var(--bg-main);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color var(--transition), color var(--transition);
}

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

a:hover {
  color: var(--accent);
}

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

ul, ol {
  list-style: none;
}

/* ========================================
   Typography
   ======================================== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  color: var(--text-primary);
}

h1 {
  font-size: clamp(2.5rem, 5vw, 3.5rem);
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(1.75rem, 3.5vw, 2.5rem);
  letter-spacing: -0.01em;
}

h3 {
  font-size: clamp(1.25rem, 2.5vw, 1.5rem);
}

p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.text-center {
  text-align: center;
}

.text-accent {
  color: var(--accent);
}

.text-primary {
  color: var(--primary);
}

/* ========================================
   Layout
   ======================================== */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 80px 0;
}

.section-alt {
  background-color: var(--bg-section-alt);
}

/* ========================================
   Navigation
   ======================================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(246, 247, 248, 0.9);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  transition: all var(--transition);
}

[data-theme="dark"] .navbar {
  background: rgba(17, 20, 24, 0.9);
}

.navbar.scrolled {
  box-shadow: var(--shadow-md);
}

.navbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.navbar-brand svg {
  width: 32px;
  height: 32px;
}

.navbar-menu {
  display: flex;
  align-items: center;
  gap: 32px;
}

.navbar-link {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition);
}

.navbar-link:hover,
.navbar-link.active {
  color: var(--primary);
}

.navbar-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.btn-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border: none;
  border-radius: var(--radius-md);
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
}

.btn-icon:hover {
  background: var(--bg-card);
  color: var(--text-primary);
}

.btn-icon svg {
  width: 20px;
  height: 20px;
}

/* Mobile Menu Button */
.menu-toggle {
  display: none;
}

@media (max-width: 768px) {
  .menu-toggle {
    display: flex;
  }
  
  .navbar-menu {
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    bottom: 0;
    flex-direction: column;
    align-items: flex-start;
    padding: 24px;
    gap: 16px;
    background: var(--bg-main);
    transform: translateX(100%);
    transition: transform var(--transition-slow);
  }
  
  .navbar-menu.active {
    transform: translateX(0);
  }
  
  .navbar-link {
    font-size: 1.125rem;
    padding: 12px 0;
    width: 100%;
    border-bottom: 1px solid var(--border);
  }
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
  padding: 140px 0 80px;
  text-align: center;
}

.hero-content {
  max-width: 800px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 100px;
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.hero-badge-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--success);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

.hero-title {
  margin-bottom: 16px;
}

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.hero-description {
  font-size: 1rem;
  color: var(--text-tertiary);
  margin-bottom: 32px;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin-bottom: 48px;
}

.hero-platforms {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  color: var(--text-tertiary);
  font-size: 0.875rem;
}

.hero-platforms svg {
  width: 20px;
  height: 20px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition);
  width: auto;
  min-width: 0;
  white-space: nowrap;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: var(--text-inverse);
  box-shadow: 0 4px 12px rgba(92, 107, 122, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(92, 107, 122, 0.4);
  color: var(--text-inverse);
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--bg-section-alt);
  color: var(--text-primary);
}

.btn-accent {
  background: linear-gradient(135deg, var(--accent), var(--accent-hover));
  color: var(--text-inverse);
  box-shadow: 0 4px 12px rgba(232, 140, 58, 0.3);
}

.btn-accent:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(232, 140, 58, 0.4);
  color: var(--text-inverse);
}

/* Hero Screenshot Placeholder */
.hero-screenshot {
  max-width: 900px;
  margin: 0 auto 48px;
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-xl);
}

.screenshot-placeholder {
  width: 100%;
  aspect-ratio: 16/10;
  background: linear-gradient(135deg, var(--bg-card), var(--bg-section-alt));
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-tertiary);
  font-size: 0.875rem;
}

/* ========================================
   Features Section
   ======================================== */
.features-header {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 64px;
}

.features-header h2 {
  margin-bottom: 16px;
}

.features-header p {
  font-size: 1.125rem;
}

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

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

@media (max-width: 640px) {
  .features-grid {
    grid-template-columns: 1fr;
  }
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px;
  transition: all var(--transition);
}

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

.feature-icon {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
  color: var(--text-inverse);
}

.feature-icon svg {
  width: 28px;
  height: 28px;
}

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

.feature-card p {
  font-size: 0.9375rem;
  margin-bottom: 16px;
}

.feature-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.feature-list li {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.feature-list li::before {
  content: "✓";
  color: var(--success);
  font-weight: 600;
  flex-shrink: 0;
}

/* Feature Screenshot Placeholder */
.feature-screenshot {
  margin-top: 20px;
  border-radius: var(--radius-md);
  overflow: hidden;
}

.feature-screenshot .screenshot-placeholder {
  aspect-ratio: 16/9;
  border-radius: var(--radius-md);
}

/* ========================================
   Chord Feature (Highlighted)
   ======================================== */
.chord-section {
  background: linear-gradient(135deg, var(--bg-card), var(--bg-section-alt));
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.chord-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
}

@media (max-width: 768px) {
  .chord-content {
    grid-template-columns: 1fr;
    gap: 40px;
  }
}

.chord-text h2 {
  margin-bottom: 16px;
}

.chord-text > p {
  font-size: 1.125rem;
  margin-bottom: 32px;
}

.chord-highlight {
  background: var(--bg-card);
  border: 1px solid var(--accent);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-bottom: 24px;
}

.chord-highlight-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 12px;
}

.chord-highlight svg {
  width: 20px;
  height: 20px;
}

.chord-example {
  background: var(--bg-code);
  border-radius: var(--radius-md);
  padding: 16px;
  font-family: 'SF Mono', 'Fira Code', monospace;
  font-size: 0.875rem;
  line-height: 1.8;
}

.chord-example .original {
  color: var(--text-secondary);
}

.chord-example .transposed {
  color: var(--success);
  font-weight: 600;
}

.chord-example .capo {
  color: var(--accent);
}

.chord-features {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.chord-features li {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  background: var(--bg-card);
  border-radius: var(--radius-md);
  font-size: 0.9375rem;
}

.chord-features li svg {
  width: 20px;
  height: 20px;
  color: var(--primary);
  flex-shrink: 0;
}

.chord-visual {
  position: relative;
}

.chord-visual .screenshot-placeholder {
  aspect-ratio: 4/3;
  border-radius: var(--radius-xl);
}

/* ========================================
   Scenarios Section
   ======================================== */
.scenarios-header {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 64px;
}

.scenarios-header h2 {
  margin-bottom: 16px;
}

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

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

@media (max-width: 640px) {
  .scenarios-grid {
    grid-template-columns: 1fr;
  }
}

.scenario-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition);
}

.scenario-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.scenario-image {
  aspect-ratio: 16/9;
  background: linear-gradient(135deg, var(--bg-section-alt), var(--bg-card));
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-tertiary);
  font-size: 0.8125rem;
}

.scenario-content {
  padding: 24px;
}

.scenario-tag {
  display: inline-block;
  padding: 4px 12px;
  background: rgba(90, 158, 112, 0.1);
  color: var(--success);
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 100px;
  margin-bottom: 12px;
}

.scenario-content h3 {
  font-size: 1.125rem;
  margin-bottom: 8px;
}

.scenario-content p {
  font-size: 0.875rem;
}

/* ========================================
   Pricing Section
   ======================================== */
.pricing-header {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 64px;
}

.pricing-header h2 {
  margin-bottom: 16px;
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
  align-items: start;
  max-width: 800px;
  margin: 0 auto;
}

@media (max-width: 640px) {
  .pricing-grid {
    grid-template-columns: 1fr;
    max-width: 400px;
  }
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  text-align: center;
  transition: all var(--transition);
}

.pricing-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.pricing-card.featured {
  border-color: var(--accent);
  position: relative;
}

.pricing-card.featured::before {
  content: "推荐";
  position: absolute;
  top: -12px;
  left: 50%;
  transform: translateX(-50%);
  padding: 4px 16px;
  background: linear-gradient(135deg, var(--accent), var(--accent-hover));
  color: var(--text-inverse);
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 100px;
}

.pricing-name {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.pricing-price {
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 4px;
}

.pricing-price span {
  font-size: 0.875rem;
  font-weight: 400;
  color: var(--text-tertiary);
}

.pricing-desc {
  font-size: 0.875rem;
  color: var(--text-tertiary);
  margin-bottom: 24px;
}

.pricing-features {
  text-align: left;
  margin-bottom: 24px;
}

.pricing-features li {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  padding: 8px 0;
  font-size: 0.875rem;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border-light);
}

.pricing-features li:last-child {
  border-bottom: none;
}

.pricing-features li svg {
  width: 16px;
  height: 16px;
  color: var(--success);
  flex-shrink: 0;
  margin-top: 2px;
}

.pricing-card .btn {
  width: 100%;
}

/* ========================================
   Download Section
   ======================================== */
.download-section {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: var(--text-inverse);
}

.download-content {
  text-align: center;
  max-width: 600px;
  margin: 0 auto;
}

.download-content h2 {
  color: var(--text-inverse);
  margin-bottom: 16px;
}

.download-content p {
  color: rgba(255, 255, 255, 0.8);
  font-size: 1.125rem;
  margin-bottom: 32px;
}

.download-badges {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin-bottom: 24px;
}

.store-badge {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 12px 24px;
  background: #000000;
  border-radius: var(--radius-md);
  color: var(--text-inverse);
  transition: all var(--transition);
}

.store-badge:hover {
  background: #1a1a1a;
  color: var(--text-inverse);
  transform: translateY(-2px);
}

.store-badge svg {
  width: 28px;
  height: 28px;
}

.store-badge-text {
  text-align: left;
}

.store-badge-text small {
  display: block;
  font-size: 0.6875rem;
  opacity: 0.8;
}

.store-badge-text strong {
  display: block;
  font-size: 1rem;
  font-weight: 600;
}

.download-info {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  font-size: 0.875rem;
  opacity: 0.8;
}

.download-info span {
  display: flex;
  align-items: center;
  gap: 6px;
}

/* ========================================
   Footer
   ======================================== */
.footer {
  background: var(--bg-card);
  border-top: 1px solid var(--border);
  padding: 64px 0 32px;
}

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

@media (max-width: 768px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 32px;
  }
}

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

.footer-brand {
  max-width: 300px;
}

.footer-brand-name {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.footer-brand-name svg {
  width: 32px;
  height: 32px;
}

.footer-brand p {
  font-size: 0.875rem;
  color: var(--text-tertiary);
  margin-bottom: 20px;
}

.footer-social {
  display: flex;
  gap: 12px;
}

.footer-social a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: var(--bg-section-alt);
  color: var(--text-secondary);
  transition: all var(--transition);
}

.footer-social a:hover {
  background: var(--primary);
  color: var(--text-inverse);
}

.footer-social a svg {
  width: 20px;
  height: 20px;
}

.footer-column h4 {
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-tertiary);
  margin-bottom: 16px;
}

.footer-column ul {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.footer-column a {
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

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

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 32px;
  border-top: 1px solid var(--border);
  font-size: 0.8125rem;
  color: var(--text-tertiary);
}

@media (max-width: 480px) {
  .footer-bottom {
    flex-direction: column;
    gap: 16px;
    text-align: center;
  }
}

/* ========================================
   Language Switcher
   ======================================== */
.lang-switcher {
  position: relative;
}

.lang-btn {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 12px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
}

.lang-btn:hover {
  border-color: var(--primary);
  color: var(--text-primary);
}

.lang-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 140px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  transition: all var(--transition);
  z-index: 100;
}

.lang-dropdown.active {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.lang-option {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  padding: 10px 16px;
  background: transparent;
  border: none;
  font-size: 0.875rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
  text-align: left;
}

.lang-option:hover {
  background: var(--bg-section-alt);
  color: var(--text-primary);
}

.lang-option.active {
  color: var(--primary);
  font-weight: 500;
}

/* ========================================
   Animations
   ======================================== */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

.fade-in-left {
  opacity: 0;
  transform: translateX(-20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

.fade-in-right {
  opacity: 0;
  transform: translateX(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* Stagger animation for grid items */
.stagger-item {
  opacity: 0;
  transform: translateY(20px);
}

.stagger-item.visible {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.4s ease, transform 0.4s ease;
}

/* ========================================
   Utilities
   ======================================== */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}