:root {
  --color-bg: #fdfcf8;
  --color-text: #3d3b37;
  --color-text-light: #7a7670;
  --color-accent: #9e8e82; /* Warm grey-brown */
  --color-primary: #8f6e5d; /* Muted reddish brown */
  --color-white: #ffffff;
  --font-serif: "Noto Serif JP", serif;
  --font-sans: "Noto Sans JP", sans-serif;
  --spacing-section: 120px;
  --spacing-container: 24px;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  font-weight: 500;
  line-height: 1.4;
  letter-spacing: 0.05em;
}

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

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

.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 var(--spacing-container);
}

/* Utilities */
.fade-in-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 1s cubic-bezier(0.2, 1, 0.3, 1), transform 1s cubic-bezier(0.2, 1, 0.3, 1);
}

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

/* Typography */
.section-title {
  font-size: 2rem;
  text-align: center;
  margin-bottom: 3rem;
  color: var(--color-text);
  position: relative;
  display: inline-block;
  width: 100%;
}

.section-title::after {
  content: "";
  display: block;
  width: 40px;
  height: 1px;
  background-color: var(--color-accent);
  margin: 1rem auto 0;
}

/* Hero Section */
.hero {
  position: relative;
  height: 100vh;
  min-height: 600px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  overflow: hidden;
  color: var(--color-white);
}

.hero-bg {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: url('./assets/hero-bg.png');
  background-size: cover;
  background-position: center;
  z-index: -1;
}

/* Overlay using a gradient for readability but maintaining atmosphere */
.hero-bg::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.3); 
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  padding: 0 20px;
}

.hero-title {
  font-size: 2.5rem; /* Mobile first adjustment, larger on desktop */
  margin-bottom: 1.5rem;
  font-weight: 500;
  text-shadow: 0 2px 10px rgba(0,0,0,0.3);
}

.hero-subtitle {
  font-size: 1.1rem;
  margin-bottom: 2rem;
  opacity: 0.9;
}

/* Problem Section */
.problem {
  padding: var(--spacing-section) 0;
  background-color: var(--color-white);
}

.problem-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
  align-items: center;
}

.problem-image img {
  border-radius: 4px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.05);
}

.problem-text h3 {
  font-size: 1.5rem;
  margin-bottom: 1.5rem;
  color: var(--color-primary);
}

.problem-text p {
  margin-bottom: 1.5rem;
}

/* Solution Section */
.solution {
  padding: var(--spacing-section) 0;
  text-align: center;
}

.solution-card {
  background: var(--color-white);
  padding: 40px;
  border-radius: 8px;
  box-shadow: 0 5px 20px rgba(0,0,0,0.03);
  margin-top: 40px;
  display: inline-block;
  max-width: 800px;
}

.solution-card img {
  border-radius: 4px;
  margin-bottom: 30px;
}

.solution-key-phrase {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  color: var(--color-primary);
  margin-bottom: 20px;
  display: block;
}

/* How It Works */
.how-it-works {
  padding: var(--spacing-section) 0;
  background-color: #f2f0eb; /* Slightly darker warm grey */
}

.steps {
  display: flex;
  flex-direction: column;
  gap: 30px;
  margin-top: 50px;
}

.step-card {
  background: var(--color-white);
  padding: 30px;
  border-radius: 8px;
  text-align: center;
  position: relative;
  flex: 1;
}

.step-number {
  display: inline-block;
  font-family: var(--font-serif);
  font-size: 3rem;
  color: rgba(143, 110, 93, 0.2);
  position: absolute;
  top: 10px;
  left: 20px;
  line-height: 1;
}

.step-title {
  margin-top: 10px;
  font-size: 1.25rem;
  margin-bottom: 15px;
}

/* Differentiation */
.differentiation {
  padding: var(--spacing-section) 0;
}

.diff-list {
  list-style: none;
  max-width: 700px;
  margin: 0 auto;
}

.diff-item {
  display: flex;
  align-items: flex-start;
  margin-bottom: 30px;
}

.diff-icon {
  font-size: 1.5rem;
  margin-right: 20px;
  line-height: 1;
}

.diff-content h4 {
  font-size: 1.2rem;
  margin-bottom: 5px;
}

.diff-content p {
  font-size: 0.95rem;
  color: var(--color-text-light);
}

/* CTA & Footer */
.cta-section {
  padding: 100px 0;
  background-color: var(--color-primary);
  color: var(--color-white);
  text-align: center;
}

.cta-button {
  display: inline-block;
  background-color: var(--color-white);
  color: var(--color-primary);
  padding: 18px 50px;
  font-size: 1.1rem;
  border-radius: 50px;
  margin-top: 30px;
  font-weight: 500;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  cursor: pointer;
  border: none;
}

.cta-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 20px rgba(0,0,0,0.15);
}

footer {
  padding: 40px 0;
  text-align: center;
  font-size: 0.8rem;
  color: var(--color-text-light);
}

/* Responsive */
@media (min-width: 768px) {
  .hero-title {
    font-size: 3.5rem;
  }
  
  .problem-grid {
    grid-template-columns: 1fr 1fr;
    gap: 60px;
  }

  .steps {
    flex-direction: row;
  }
}