/* ==========================================
   K-one Night Design System
   Apple/Stripe-inspired Premium LP
   ========================================== */

/* ==========================================
   1. CSS Variables & Design Tokens
   ========================================== */
:root {
  /* Colors - 60:30:10 Rule */
  --color-primary: #0A1628;
  --color-primary-light: #1a2940;
  --color-primary-dark: #050b14;
  
  --color-secondary: #D4AF37;
  --color-secondary-light: #e6c966;
  --color-secondary-dark: #b8941f;
  
  --color-accent: #FFD700;
  --color-accent-hover: #FFC700;
  
  --color-text-primary: #1a1a1a;
  --color-text-secondary: #4a4a4a;
  --color-text-tertiary: #8a8a8a;
  --color-text-inverse: #ffffff;
  
  --color-background: #ffffff;
  --color-background-alt: #f8f9fa;
  --color-background-dark: #0A1628;
  
  /* Typography - Golden Ratio Scale (1.618) - Mobile First */
  --font-family-primary: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", "Hiragino Sans", sans-serif;
  --font-family-heading: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", sans-serif;
  
  --font-size-xs: 0.75rem;      /* 12px */
  --font-size-sm: 0.875rem;     /* 14px */
  --font-size-base: 0.9375rem;  /* 15px - モバイル最適化 */
  --font-size-lg: 1.0625rem;    /* 17px - モバイル最適化 */
  --font-size-xl: 1.125rem;     /* 18px */
  --font-size-2xl: 1.375rem;    /* 22px - モバイル最適化 */
  --font-size-3xl: 1.75rem;     /* 28px - モバイル最適化 */
  --font-size-4xl: 2.25rem;     /* 36px - モバイル最適化 */
  
  --font-weight-regular: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  --line-height-tight: 1.2;
  --line-height-normal: 1.618;
  --line-height-relaxed: 1.8;
  
  /* Spacing - 8px Grid System */
  --space-1: 0.5rem;   /* 8px */
  --space-2: 1rem;     /* 16px */
  --space-3: 1.5rem;   /* 24px */
  --space-4: 2rem;     /* 32px */
  --space-5: 2.5rem;   /* 40px */
  --space-6: 3rem;     /* 48px */
  --space-8: 4rem;     /* 64px */
  --space-10: 5rem;    /* 80px */
  --space-12: 6rem;    /* 96px */
  --space-16: 8rem;    /* 128px */
  
  /* Shadows - Multi-layer Soft Shadows */
  --shadow-sm: 
    0 1px 2px rgba(0, 0, 0, 0.04),
    0 1px 4px rgba(0, 0, 0, 0.04);
  
  --shadow-md: 
    0 2px 4px rgba(0, 0, 0, 0.06),
    0 4px 8px rgba(0, 0, 0, 0.06),
    0 8px 16px rgba(0, 0, 0, 0.06);
  
  --shadow-lg: 
    0 4px 6px rgba(0, 0, 0, 0.07),
    0 8px 16px rgba(0, 0, 0, 0.07),
    0 16px 32px rgba(0, 0, 0, 0.07);
  
  --shadow-xl: 
    0 8px 16px rgba(0, 0, 0, 0.08),
    0 16px 32px rgba(0, 0, 0, 0.08),
    0 32px 64px rgba(0, 0, 0, 0.08);
  
  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-2xl: 24px;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
  
  /* Layout */
  --container-max-width: 1200px;
  --content-max-width: 800px;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family-primary);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-background);
  overflow-x: hidden;
}

/* ==========================================
   3. Typography System
   ========================================== */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-family-heading);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  color: var(--color-text-primary);
  margin-bottom: var(--space-3);
}

h1 {
  font-size: var(--font-size-4xl);
  letter-spacing: -0.02em;
}

h2 {
  font-size: var(--font-size-3xl);
  letter-spacing: -0.01em;
}

h3 {
  font-size: var(--font-size-2xl);
}

h4 {
  font-size: var(--font-size-xl);
}

h5 {
  font-size: var(--font-size-lg);
}

h6 {
  font-size: var(--font-size-base);
}

p {
  margin-bottom: var(--space-3);
  color: var(--color-text-secondary);
}

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

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

/* ==========================================
   4. Layout Components
   ========================================== */
.container {
  width: 100%;
  max-width: var(--container-max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-4);
  padding-right: var(--space-4);
}

.section {
  padding-top: var(--space-12);
  padding-bottom: var(--space-12);
}

.section--dark {
  background-color: var(--color-background-dark);
  color: var(--color-text-inverse);
}

.section--dark h1,
.section--dark h2,
.section--dark h3,
.section--dark h4,
.section--dark h5,
.section--dark h6 {
  color: var(--color-text-inverse);
}

.section--dark p {
  color: rgba(255, 255, 255, 0.8);
}

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

/* ==========================================
   5. Header & Navigation
   ========================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background-color: rgba(10, 22, 40, 0.95);
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-sm);
  transition: background-color var(--transition-base), box-shadow var(--transition-base);
}

.header.scrolled {
  background-color: rgba(10, 22, 40, 0.98);
  box-shadow: var(--shadow-md);
}

.header__container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.header__logo {
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-accent);
  letter-spacing: 0.05em;
}

.header__nav {
  display: flex;
  gap: var(--space-6);
}

.header__nav-link {
  color: var(--color-text-inverse);
  font-weight: var(--font-weight-medium);
  font-size: var(--font-size-base);
  opacity: 0.9;
  transition: opacity var(--transition-fast), color var(--transition-fast);
}

.header__nav-link:hover {
  opacity: 1;
  color: var(--color-accent);
}

.header__social-link {
  color: var(--color-text-inverse);
  font-size: 1.75rem;
  opacity: 1;
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.15);
  margin-left: var(--space-2);
}

.header__social-link:hover {
  transform: translateY(-3px) scale(1.1);
  background: rgba(255, 255, 255, 0.25);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.header__social-link .fa-instagram {
  color: #E4405F;
}

.header__social-link .fa-line {
  color: #06C755;
}

.header__social-link:hover .fa-instagram {
  color: #E4405F;
  filter: brightness(1.2) drop-shadow(0 2px 8px rgba(228, 64, 95, 0.5));
}

.header__social-link:hover .fa-line {
  color: #06C755;
  filter: brightness(1.2) drop-shadow(0 2px 8px rgba(6, 199, 85, 0.5));
}

/* ==========================================
   6. Hero Section
   ========================================== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding-top: 72px;
  overflow: hidden;
  background-image: url('/static/hero-bg.png');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  background-attachment: fixed;
}

.hero__overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(
    135deg,
    rgba(10, 22, 40, 0.70) 0%,
    rgba(26, 41, 64, 0.60) 50%,
    rgba(10, 22, 40, 0.70) 100%
  );
  z-index: 0;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-image: 
    radial-gradient(circle at 20% 50%, rgba(212, 175, 55, 0.15) 0%, transparent 50%),
    radial-gradient(circle at 80% 80%, rgba(255, 215, 0, 0.1) 0%, transparent 50%);
  pointer-events: none;
  z-index: 1;
}

.hero__content {
  position: relative;
  z-index: 2;
  text-align: center;
  max-width: 900px;
  padding: var(--space-5) var(--space-4);
  background: rgba(10, 22, 40, 0.45);
  border-radius: 16px;
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 215, 0, 0.2);
}

.hero__title {
  font-size: clamp(1.75rem, 8vw, 5rem);
  color: #FFFFFF;
  margin-bottom: var(--space-3);
  animation: fadeInUp 1s cubic-bezier(0.4, 0, 0.2, 1);
  text-shadow: 
    0 2px 4px rgba(0, 0, 0, 1),
    0 4px 8px rgba(0, 0, 0, 0.9),
    0 8px 16px rgba(0, 0, 0, 0.8),
    0 16px 32px rgba(0, 0, 0, 0.6);
  font-weight: 700;
  letter-spacing: 0.02em;
  line-height: 1.3;
}

.hero__subtitle {
  font-size: clamp(0.9375rem, 4vw, 1.25rem);
  color: #FFFFFF;
  margin-bottom: var(--space-6);
  animation: fadeInUp 1s cubic-bezier(0.4, 0, 0.2, 1) 0.2s backwards;
  text-shadow: 
    0 2px 4px rgba(0, 0, 0, 1),
    0 4px 8px rgba(0, 0, 0, 0.9),
    0 8px 16px rgba(0, 0, 0, 0.7);
  font-weight: 500;
  line-height: 1.7;
  letter-spacing: 0.01em;
}

.hero__cta {
  display: inline-flex;
  gap: var(--space-3);
  animation: fadeInUp 1s cubic-bezier(0.4, 0, 0.2, 1) 0.4s backwards;
}

.hero__cta-wrapper {
  display: flex;
  gap: var(--space-4);
  align-items: center;
  justify-content: center;
  width: 100%;
  max-width: 700px;
  margin: 0 auto;
  animation: fadeInUp 1s cubic-bezier(0.4, 0, 0.2, 1) 0.4s backwards;
}

/* LINE Official Button Design */
.hero__line-official-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
  width: 100%;
  max-width: 100%;
  padding: var(--space-4) var(--space-6);
  background: linear-gradient(135deg, #06C755 0%, #00B900 100%);
  border: none;
  border-radius: 100px;
  color: white;
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-bold);
  text-decoration: none;
  box-shadow: 
    0 8px 24px rgba(6, 199, 85, 0.4),
    0 4px 12px rgba(0, 0, 0, 0.15);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.hero__line-official-btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background-color: rgba(0, 0, 0, 0.1);
  transform: translate(-50%, -50%);
  transition: width var(--transition-slow), height var(--transition-slow);
}

.hero__line-official-btn:hover {
  transform: translateY(-4px);
  box-shadow: 
    0 12px 32px rgba(6, 199, 85, 0.5),
    0 8px 16px rgba(0, 0, 0, 0.2);
  background: linear-gradient(135deg, #05B84D 0%, #009900 100%);
}

.hero__line-official-btn:hover::before {
  width: 500px;
  height: 500px;
}

.hero__line-official-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background: white;
  border-radius: 50%;
  flex-shrink: 0;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  position: relative;
  z-index: 1;
  font-size: 1.125rem;
  color: #06C755;
}

.hero__line-official-text {
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-bold);
  letter-spacing: 0.02em;
  line-height: 1.2;
  position: relative;
  z-index: 1;
}

/* ==========================================
   7. Button Components
   ========================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-3) var(--space-6);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-semibold);
  border-radius: var(--radius-lg);
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background-color: rgba(255, 255, 255, 0.3);
  transform: translate(-50%, -50%);
  transition: width var(--transition-slow), height var(--transition-slow);
}

.btn:hover::before {
  width: 300px;
  height: 300px;
}

.btn--primary {
  background: linear-gradient(135deg, var(--color-secondary) 0%, var(--color-accent) 100%);
  color: var(--color-primary);
  box-shadow: var(--shadow-md);
}

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

.btn--secondary {
  background-color: transparent;
  color: var(--color-text-inverse);
  border: 2px solid var(--color-secondary);
}

.btn--secondary:hover {
  background-color: var(--color-secondary);
  color: var(--color-primary);
}

.btn--large {
  padding: var(--space-4) var(--space-8);
  font-size: var(--font-size-lg);
}

/* ==========================================
   8. Card Components
   ========================================== */
.card {
  background-color: var(--color-background);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  box-shadow: var(--shadow-md);
  transition: all var(--transition-base);
  border: 1px solid rgba(0, 0, 0, 0.05);
}

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

.card__title {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--space-3);
  color: var(--color-text-primary);
}

.card__description {
  font-size: var(--font-size-base);
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
  margin-bottom: var(--space-4);
}

.card__price {
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-secondary);
  margin-bottom: var(--space-2);
}

.card__price-note {
  font-size: var(--font-size-sm);
  color: var(--color-text-tertiary);
}

.card--dark {
  background-color: var(--color-primary-light);
  border-color: rgba(255, 255, 255, 0.1);
}

.card--dark .card__title {
  color: var(--color-text-inverse);
}

.card--dark .card__description {
  color: rgba(255, 255, 255, 0.8);
}

/* ==========================================
   9. Grid System
   ========================================== */
.grid {
  display: grid;
  gap: var(--space-6);
}

.grid--2 {
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.grid--3 {
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
}

.grid--4 {
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

/* ==========================================
   10. Service Cards
   ========================================== */
.service-card {
  position: relative;
  background: linear-gradient(135deg, rgba(255, 255, 255, 0.05) 0%, rgba(255, 255, 255, 0.02) 100%);
  border: 1px solid rgba(212, 175, 55, 0.2);
  border-radius: var(--radius-xl);
  padding: var(--space-5);
  transition: all var(--transition-base);
  overflow: hidden;
}

.service-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--color-secondary) 0%, var(--color-accent) 100%);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--transition-base);
}

.service-card:hover::before {
  transform: scaleX(1);
}

.service-card:hover {
  transform: translateY(-8px);
  border-color: var(--color-secondary);
  box-shadow: var(--shadow-xl);
}

.service-card__icon {
  width: 64px;
  height: 64px;
  background: linear-gradient(135deg, var(--color-secondary) 0%, var(--color-accent) 100%);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--font-size-2xl);
  margin-bottom: var(--space-4);
}

/* ==========================================
   11. Table of Contents
   ========================================== */
.toc {
  background-color: var(--color-background-alt);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  margin-bottom: var(--space-8);
  border-left: 4px solid var(--color-secondary);
}

.toc__title {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-4);
  color: var(--color-text-primary);
}

.toc__list {
  list-style: none;
}

.toc__item {
  margin-bottom: var(--space-2);
}

.toc__link {
  color: var(--color-text-secondary);
  font-size: var(--font-size-base);
  transition: all var(--transition-fast);
  display: block;
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius-sm);
}

.toc__link:hover {
  color: var(--color-secondary);
  background-color: rgba(212, 175, 55, 0.1);
  padding-left: var(--space-3);
}

/* ==========================================
   12. Footer
   ========================================== */
.footer {
  background-color: var(--color-primary-dark);
  color: var(--color-text-inverse);
  padding: var(--space-12) 0 var(--space-6);
}

.footer__content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}

.footer__section-title {
  font-size: var(--font-size-lg);
  margin-bottom: var(--space-4);
  color: var(--color-accent);
}

.footer__link {
  display: block;
  color: rgba(255, 255, 255, 0.7);
  margin-bottom: var(--space-2);
  transition: color var(--transition-fast);
}

.footer__link:hover {
  color: var(--color-accent);
}

.footer__bottom {
  text-align: center;
  padding-top: var(--space-6);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  color: rgba(255, 255, 255, 0.5);
  font-size: var(--font-size-sm);
}

/* ==========================================
   13. Animations
   ========================================== */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

.fade-in {
  animation: fadeIn 1s cubic-bezier(0.4, 0, 0.2, 1);
}

.fade-in-up {
  animation: fadeInUp 1s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Scroll-triggered animations */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1),
              transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

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

/* ==========================================
   14. Responsive Design (Mobile First)
   ========================================== */
@media (max-width: 768px) {
  :root {
    --font-size-4xl: 2.5rem;
    --font-size-3xl: 2rem;
    --font-size-2xl: 1.5rem;
  }
  
  .container {
    padding-left: var(--space-3);
    padding-right: var(--space-3);
  }
  
  .section {
    padding-top: var(--space-8);
    padding-bottom: var(--space-8);
  }
  
  .header__nav {
    display: none;
  }
  
  .hero__cta-wrapper {
    max-width: 100%;
    gap: var(--space-3);
  }
  
  .hero__cta-wrapper {
    max-width: 100%;
    gap: var(--space-3);
  }
  
  .hero__line-official-btn {
    padding: var(--space-5) var(--space-6);
    font-size: var(--font-size-2xl);
    gap: var(--space-3);
  }
  
  .hero__line-official-icon {
    width: 28px;
    height: 28px;
    font-size: 1rem;
  }
  
  .hero__line-official-text {
    font-size: var(--font-size-2xl);
  }
  
  .hero__service-btn {
    padding: var(--space-3) var(--space-5);
    font-size: var(--font-size-base);
  }
  
  .btn {
    width: 100%;
  }
  
  .grid--2,
  .grid--3,
  .grid--4 {
    grid-template-columns: 1fr;
  }
  
  .service-card {
    padding: var(--space-4);
  }
}

@media (min-width: 769px) and (max-width: 1024px) {
  .grid--4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* ==========================================
   15. Utility Classes
   ========================================== */
.text-center {
  text-align: center;
}

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

.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }

.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }

.text-primary { color: var(--color-text-primary); }
.text-secondary { color: var(--color-text-secondary); }
.text-tertiary { color: var(--color-text-tertiary); }
.text-inverse { color: var(--color-text-inverse); }
.text-gold { color: var(--color-secondary); }

.fw-regular { font-weight: var(--font-weight-regular); }
.fw-medium { font-weight: var(--font-weight-medium); }
.fw-semibold { font-weight: var(--font-weight-semibold); }
.fw-bold { font-weight: var(--font-weight-bold); }

/* ==========================================
   16. LINE Button Component
   ========================================== */
.btn-line {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-3) var(--space-6);
  background: linear-gradient(135deg, #06C755 0%, #00B900 100%);
  color: white;
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-semibold);
  border-radius: var(--radius-lg);
  border: none;
  cursor: pointer;
  text-decoration: none;
  transition: all var(--transition-base);
  box-shadow: var(--shadow-md);
  position: relative;
  overflow: hidden;
}

.btn-line::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background-color: rgba(255, 255, 255, 0.3);
  transform: translate(-50%, -50%);
  transition: width var(--transition-slow), height var(--transition-slow);
}

.btn-line:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  background: linear-gradient(135deg, #05B84D 0%, #009900 100%);
}

.btn-line:hover::before {
  width: 300px;
  height: 300px;
}

.btn-line--large {
  padding: var(--space-4) var(--space-8);
  font-size: var(--font-size-lg);
}

.btn-line--icon {
  font-size: 1.25em;
  margin-right: var(--space-2);
}

.line-cta-box {
  background: linear-gradient(135deg, rgba(6, 199, 85, 0.1) 0%, rgba(0, 185, 0, 0.05) 100%);
  border: 2px solid rgba(6, 199, 85, 0.3);
  border-radius: var(--radius-2xl);
  padding: var(--space-8);
  text-align: center;
  margin-top: var(--space-8);
  margin-bottom: var(--space-8);
}

.line-cta-box__icon {
  font-size: 4rem;
  color: #06C755;
  margin-bottom: var(--space-4);
}

.line-cta-box__title {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--space-3);
  color: var(--color-text-primary);
}

.line-cta-box__description {
  font-size: var(--font-size-base);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-6);
  line-height: var(--line-height-relaxed);
}

.line-cta-box--dark {
  background: linear-gradient(135deg, rgba(6, 199, 85, 0.15) 0%, rgba(0, 185, 0, 0.1) 100%);
  border-color: rgba(6, 199, 85, 0.4);
}

.line-cta-box--dark .line-cta-box__title {
  color: var(--color-text-inverse);
}

.line-cta-box--dark .line-cta-box__description {
  color: rgba(255, 255, 255, 0.8);
}

/* Floating LINE Button (Fixed Position) */
.line-floating-btn {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  z-index: 999;
  width: 64px;
  height: 64px;
  background: linear-gradient(135deg, #06C755 0%, #00B900 100%);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 2rem;
  box-shadow: var(--shadow-xl);
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
  animation: pulse 2s infinite;
}

.line-floating-btn:hover {
  transform: scale(1.1);
  box-shadow: 0 8px 32px rgba(6, 199, 85, 0.4);
}

@keyframes pulse {
  0% {
    box-shadow: 0 8px 16px rgba(6, 199, 85, 0.3);
  }
  50% {
    box-shadow: 0 8px 32px rgba(6, 199, 85, 0.5);
  }
  100% {
    box-shadow: 0 8px 16px rgba(6, 199, 85, 0.3);
  }
}

@media (max-width: 768px) {
  .line-floating-btn {
    bottom: var(--space-4);
    right: var(--space-4);
    width: 56px;
    height: 56px;
    font-size: 1.75rem;
  }
}

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

:focus-visible {
  outline: 2px solid var(--color-secondary);
  outline-offset: 4px;
}