:root {
  --primary-color: #1D4ED8;
  /* Defined Blue */
  --primary-hover: #1e40af;
  --bg-color: #ffffff;
  --bg-gradient-start: #ffffff;
  --bg-gradient-end: #eff6ff;
  /* Pale blue */
  --text-main: #1f2937;
  --text-sub: #4b5563;
  --text-inverse: #ffffff;
  --border-color: #e5e7eb;
  --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --section-padding: 4rem 1rem;
  --max-width: 1200px;
  /* System fonts are often the most legible and "thickest" rendering on native devices */
  --font-family: "Hiragino Kaku Gothic ProN", "Hiragino Sans", Meiryo, sans-serif;
}

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

body {
  font-family: var(--font-family);
  color: #000000;
  /* Pure black for maximum strength */
  background: var(--bg-color);
  background: linear-gradient(180deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
  line-height: 1.75;
  font-weight: 500;
  /* Increased from normal (400) to Medium (500) */
  -webkit-font-smoothing: auto;
  /* Disable antialiasing smoothing which thins text */
}

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

/* Lightbox styles */
.zoom-trigger {
  cursor: pointer;
  transition: transform 0.2s ease;
}

.zoom-trigger:hover {
  transform: scale(1.02);
}

.lightbox-modal {
  display: none;
  /* Hidden by default */
  position: fixed;
  z-index: 1000;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.9);
  align-items: center;
  justify-content: center;
  cursor: pointer;
  /* Click anywhere to close */
}

.lightbox-img {
  max-width: 95%;
  max-height: 95%;
  object-fit: contain;
  box-shadow: 0 0 20px rgba(255, 255, 255, 0.1);
}

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

/* Layout */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1rem;
}

header {
  padding: 1.5rem 0;
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(10px);
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid var(--border-color);
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Typography */
h1,
h2,
h3,
h4,
h5,
h6 {
  line-height: 1.3;
  margin-bottom: 1rem;
}

h2 {
  font-size: 2.25rem;
  text-align: center;
  margin-bottom: 3rem;
  color: var(--text-main);
  position: relative;
  display: inline-block;
  width: 100%;
}

h2::after {
  content: '';
  display: block;
  width: 60px;
  height: 4px;
  background: var(--primary-color);
  margin: 1rem auto 0;
  border-radius: 2px;
}

p {
  margin-bottom: 1rem;
}

.text-accent {
  color: var(--primary-color);
  font-weight: 700;
}

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

.br-sp {
  display: none;
}

.text-sm {
  font-size: 0.875rem;
}

/* Components */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  background-color: var(--primary-color);
  color: var(--text-inverse);
  font-weight: 700;
  border-radius: 9999px;
  transition: background-color 0.3s ease;
  cursor: pointer;
  border: none;
}

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

.card {
  background: #ffffff;
  border-radius: 1rem;
  padding: 2rem;
  box-shadow: var(--card-shadow);
  border: 1px solid var(--border-color);
  height: 100%;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

/* Hero Section */
.hero {
  padding: 6rem 1rem;
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 1.5rem;
  background: -webkit-linear-gradient(45deg, var(--text-main), var(--primary-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-sub);
}

/* Sections */
section {
  padding: var(--section-padding);
}

.bg-white {
  background-color: #ffffff;
}

/* Plans Grid */
.plans-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

.plan-card h3 {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}

.price {
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary-color);
  margin-bottom: 1.5rem;
}

.plan-features li {
  margin-bottom: 0.75rem;
  padding-left: 1.5rem;
  position: relative;
}

.plan-features li::before {
  content: '✓';
  color: var(--primary-color);
  position: absolute;
  left: 0;
  font-weight: bold;
}

/* Terminology */
.term-list dl {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  max-width: 800px;
  margin: 0 auto;
}

@media (min-width: 640px) {
  .term-list dl {
    grid-template-columns: auto 1fr;
    gap: 1rem 2rem;
  }
}

.term-list dt {
  font-weight: 700;
  color: var(--primary-color);
  min-width: 180px;
}

.term-list dd {
  color: var(--text-sub);
  margin-left: 0;
}

/* Options */
.options-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

/* Selection Guide */
.flow-step {
  background: white;
  padding: 1.5rem;
  border-left: 4px solid var(--primary-color);
  margin-bottom: 1rem;
  border-radius: 0.5rem;
  box-shadow: var(--card-shadow);
}

.flow-step strong {
  font-size: 1.1em;
}

/* Note Alert */
.alert-box {
  background-color: #eff6ff;
  border: 1px solid #bfdbfe;
  color: #1e40af;
  padding: 1rem;
  border-radius: 0.5rem;
  max-width: 800px;
  margin: 2rem auto;
  text-align: center;
  font-size: 0.9rem;
}

/* Mobile Adjustments */
@media (max-width: 768px) {
  :root {
    --section-padding: 3rem 1rem;
    /* Reduced from 4rem */
  }

  /* Typography */
  h1 {
    font-size: 2rem;
    line-height: 1.25;
  }

  h2 {
    font-size: 1.75rem;
    margin-bottom: 2rem;
  }

  h3 {
    font-size: 1.25rem;
  }

  p {
    font-size: 1rem;
    line-height: 1.7;
  }

  .hero h1 {
    font-size: 2.25rem;
    /* Better balance than 2rem but smaller than 3rem */
  }

  .hero p {
    font-size: 1rem;
    text-align: left;
    width: 100%;
    display: block;
  }

  /* Layout Spacing */
  .hero {
    padding: 3rem 1rem;
    /* Keeping main container center, but text left */
  }

  /* Utilities Mobile */
  .text-left-sp {
    text-align: left !important;
    width: 100%;
    display: block;
  }

  .alert-box {
    text-align: left;
  }

  .container {
    padding: 0 1.25rem;
    /* Slightly more breathing room on edges */
  }

  .card {
    padding: 1.5rem;
    /* Save space inside cards */
  }

  /* Grids & Flex */
  .plans-grid,
  .options-grid {
    gap: 1.5rem;
    /* Tighten gaps */
  }

  /* Terminology List Mobile Override */
  .term-list dl {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }

  .term-list dt {
    margin-bottom: 0.25rem;
  }

  .term-list dd {
    margin-bottom: 1rem;
    padding-left: 0.5rem;
    border-left: 2px solid #e5e7eb;
  }

  /* Button touch targets */
  /* Utilities */
  .br-pc {
    display: none;
  }

  .br-sp {
    display: block;
    margin-bottom: 0.5rem;
    /* Optional: add a bit of space if needed, but block break is enough */
  }

  .btn {
    width: 100%;
    /* Full width buttons often feel better on mobile */
    text-align: center;
    padding: 1rem;
  }
}

/* Small mobile devices */
@media (max-width: 375px) {
  h1 {
    font-size: 1.75rem;
  }

  h2 {
    font-size: 1.5rem;
  }

  .hero h1 {
    font-size: 2rem;
  }
}