:root {
  --bg-primary: #fcf9f2;
  /* Washi-like off-white */
  --bg-secondary: #f2efe6;
  /* Slightly darker sidebar */
  --bg-card: #ffffff;
  /* Clean white for cards */
  --text-primary: #333333;
  /* Dark gray for readability */
  --text-secondary: #5a5a5a;
  --accent: #a33e36;
  /* Traditional Japanese Red (Benikaba-like) */
  --accent-hover: #c4554d;
  --border: #e6e2d8;
  --sidebar-width: 280px;
}

/* ===== Reset ===== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Noto Sans JP', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.8;
  min-height: 100vh;
}

/* ===== Layout ===== */
.container {
  display: flex;
  min-height: 100vh;
}

/* ===== Sidebar ===== */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border);
  position: fixed;
  height: 100vh;
  overflow-y: auto;
  padding: 24px 0;
}

.sidebar-header {
  padding: 0 20px 24px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 16px;
}

.sidebar-header h1 {
  font-size: 18px;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 4px;
}

.sidebar-header p {
  font-size: 12px;
  color: var(--text-secondary);
}

.nav-section {
  padding: 0 12px;
  margin-bottom: 24px;
}

.nav-section-title {
  font-size: 11px;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 8px 8px;
  margin-bottom: 4px;
}

.nav-item {
  display: block;
  padding: 10px 16px;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 14px;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.15s ease;
  margin-bottom: 2px;
}

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

.nav-item.active {
  background: var(--accent);
  color: white;
}

.nav-item .day-label {
  font-weight: 600;
  margin-right: 8px;
}

/* ===== Main Content ===== */
.main-content {
  margin-left: var(--sidebar-width);
  flex: 1;
  padding: 40px 60px;
  max-width: 900px;
}

.content-section {
  display: none;
}

.content-section.active {
  display: block;
}

/* ===== Content Styles ===== */
.content-header {
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border);
}

.content-header h2 {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 8px;
}

.content-header .subtitle {
  color: var(--text-secondary);
  font-size: 14px;
}

.mail-title {
  background: linear-gradient(135deg, var(--accent), var(--accent-hover));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 32px;
}

.mail-body {
  font-size: 15px;
  line-height: 2;
  color: var(--text-primary);
}

.mail-body p {
  margin-bottom: 16px;
}

.mail-body strong {
  color: var(--accent-hover);
}

.mail-body hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 32px 0;
}

.mail-body ul,
.mail-body ol {
  margin: 16px 0;
  padding-left: 24px;
}

.mail-body li {
  margin-bottom: 8px;
}

.postscript {
  margin-top: 40px;
  padding: 24px;
  background: var(--bg-card);
  border-radius: 12px;
  border-left: 4px solid var(--accent);
}

.postscript h3 {
  font-size: 14px;
  color: var(--accent);
  margin-bottom: 16px;
}

/* ===== Concept Page ===== */
.concept-section {
  margin-bottom: 40px;
}

.concept-section h3 {
  font-size: 18px;
  font-weight: 600;
  color: var(--accent-hover);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.concept-section h3::before {
  content: '';
  width: 4px;
  height: 18px;
  background: var(--accent);
  border-radius: 2px;
}

.concept-card {
  background: var(--bg-card);
  border-radius: 12px;
  padding: 24px;
  margin-bottom: 16px;
}

.concept-card p {
  margin-bottom: 12px;
}

.concept-card ul {
  list-style: none;
  padding: 0;
}

.concept-card li {
  padding: 8px 0;
  padding-left: 24px;
  position: relative;
}

.concept-card li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--accent);
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
}

th,
td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

th {
  background: var(--bg-card);
  font-weight: 600;
  color: var(--accent-hover);
}

/* ===== Testimonial ===== */
.testimonial {
  background: var(--bg-card);
  border-radius: 12px;
  padding: 24px;
  margin: 24px 0;
  border-left: 4px solid var(--accent);
}

.testimonial-header {
  font-weight: 600;
  color: var(--accent-hover);
  margin-bottom: 12px;
}

/* ===== Mobile Responsive ===== */
@media (max-width: 768px) {
  .sidebar {
    width: 100%;
    position: relative;
    height: auto;
  }

  .main-content {
    margin-left: 0;
    padding: 24px;
  }

  .container {
    flex-direction: column;
  }
}

/* Sales Letter Styles */
.sales-letter-head {
  background: linear-gradient(rgba(252, 249, 242, 0.85), rgba(252, 249, 242, 0.95)), url('https://images.unsplash.com/photo-1518531933037-9a847e0f3886?fit=crop&w=1600&h=900') no-repeat center center;
  background-size: cover;
  padding: 60px 20px;
  margin: -40px -40px 40px -40px;
  text-align: center;
  border-radius: 0 0 20px 20px;
  border-bottom: 3px solid var(--accent);
}

.sales-letter-head h1 {
  color: var(--text-primary);
  font-size: 2.2rem;
  margin-bottom: 20px;
  line-height: 1.4;
  text-shadow: 0 1px 2px rgba(255, 255, 255, 0.8);
}

.sales-letter-head p {
  color: var(--text-secondary);
  font-size: 1.1rem;
  max-width: 800px;
  margin: 0 auto;
  font-weight: 500;
}

.highlight-box {
  background-color: #fffbf0;
  /* Warm paper tint */
  border: 2px solid var(--accent);
  border-radius: 12px;
  padding: 24px;
  margin: 30px 0;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

.testimonial-box {
  background-color: var(--bg-card);
  border-left: 4px solid var(--accent);
  padding: 20px;
  margin: 20px 0;
  border-radius: 0 8px 8px 0;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

.price-display {
  text-align: center;
  margin: 40px 0;
  padding: 30px;
  background-color: #fff;
  border-radius: 16px;
  border: 3px double var(--accent);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.old-price {
  text-decoration: line-through;
  color: var(--text-secondary);
  font-size: 1.2rem;
}

.new-price {
  color: #d3381c;
  /* Traditional Vermilion */
  /* Red-ish accent for price */
  font-size: 2.5rem;
  font-weight: 700;
  margin: 10px 0;
}

.cta-button {
  display: block;
  width: 100%;
  max-width: 500px;
  margin: 30px auto;
  padding: 20px;
  background: linear-gradient(135deg, #a33e36, #cf5a50);
  color: white;
  text-align: center;
  font-weight: bold;
  font-size: 1.3rem;
  border-radius: 50px;
  text-decoration: none;
  box-shadow: 0 10px 20px rgba(163, 62, 54, 0.3);
  transition: transform 0.2s, box-shadow 0.2s;
}

.cta-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 15px 30px rgba(163, 62, 54, 0.4);
}

.guarantee-badge {
  text-align: center;
  margin-top: 10px;
  font-size: 0.9rem;
  color: var(--text-secondary);
}