:root {
  /* Colors - Based on en-ren theme */
  --primary-color: #1E293B;
  /* Lighter Blue */
  --primary-gradient: linear-gradient(135deg, #0F172A, #1E293B);
  --secondary-color: #10B981;
  /* Secondary Green */
  --secondary-gradient: linear-gradient(135deg, #10B981, #059669);
  --gold: #F59E0B;
  /* Gold */
  --bg-color: #f8fafc;
  --surface-color: #ffffff;
  --text-color: #1e293b;
  --text-light: #64748b;
  --white: #ffffff;
  --shadow-sm: 0 4px 6px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 10px 20px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 20px 40px rgba(0, 0, 0, 0.12);
  --radius-sm: 8px;
  --radius-md: 20px;
  --radius-lg: 40px;
  --font-family: 'Inter', 'Noto Sans JP', -apple-system, BlinkMacSystemFont, sans-serif;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

a {
  text-decoration: none;
  color: inherit;
  transition: color 0.3s;
}

ul {
  list-style: none;
}

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

/* Header */
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 5%;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: var(--shadow-sm);
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
}

nav ul {
  display: flex;
  gap: 20px;
}

nav a {
  font-weight: 500;
  color: var(--text-color);
}

nav a:hover {
  color: var(--secondary-color);
}

/* Hero Section */
.hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 100px 5% 60px;
  background: white;
  overflow: hidden;
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 16px;
  font-weight: 800;
  line-height: 1.3;
  letter-spacing: -0.01em;
}

.hero .highlight {
  color: var(--secondary-color);
  display: inline-block;
}

.hero .tagline {
  font-size: 1.25rem;
  color: var(--text-light);
  margin-bottom: 32px;
  max-width: 600px;
  line-height: 1.6;
}

/* Concept Section (Story) */
.concept {
  padding: 80px 5%;
  background: var(--surface-color);
  display: flex;
  justify-content: center;
}

.concept-content {
  max-width: 800px;
  text-align: center;
}

.concept h2 {
  font-size: 2rem;
  margin-bottom: 30px;
  position: relative;
  display: inline-block;
}

.concept h2::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 50%;
  transform: translateX(-50%);
  width: 50px;
  height: 3px;
  background: var(--gold);
  border-radius: 2px;
}

.concept p {
  font-size: 1.15rem;
  color: var(--text-light);
  margin-bottom: 24px;
  line-height: 2;
  text-align: center;
}

.keep-phrase {
  display: inline-block;
  vertical-align: top;
  text-align: left;
}

.concept b {
  color: var(--text-color);
  background: linear-gradient(transparent 70%, rgba(245, 158, 11, 0.2) 70%);
}

.download-badges {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin: 30px 0;
}

.hero-mockup img {
  width: 100%;
  max-width: 400px;
  /* タイトル画面は縦長なので幅を制限 */
  height: auto;
  border-radius: 30px;
  box-shadow: var(--shadow-lg);
  display: block;
  margin: 0 auto;
  transition: var(--transition);
}

.hero-mockup:hover img {
  transform: translateY(-10px) scale(1.02);
}

/* Gallery / Screenshots */
.gallery {
  padding: 80px 5%;
  background: var(--white);
}

.screenshot-container {
  display: flex;
  gap: 20px;
  overflow-x: auto;
  padding: 20px 0;
  scrollbar-width: none;
  /* Firefox */
}

.screenshot-container::-webkit-scrollbar {
  display: none;
  /* Chrome */
}

.screenshot-img {
  flex: 0 0 auto;
  height: 500px;
  border-radius: 30px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s;
}

.screenshot-img:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.15);
}

/* Features */
.features {
  padding: 100px 5%;
  background: var(--bg-color);
}

.section-title {
  text-align: center;
  font-size: 2.2rem;
  margin-bottom: 60px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
  max-width: 1200px;
  margin: 0 auto;
}

.feature-card {
  background: var(--white);
  padding: 40px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  transition: transform 0.3s;
}

.feature-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
}

.feature-icon {
  font-size: 2.5rem;
  margin-bottom: 20px;
  display: block;
  color: var(--gold);
}

.feature-card h3 {
  margin-bottom: 15px;
  font-size: 1.4rem;
}

.feature-card p {
  color: var(--text-light);
}

/* CTA Section */
.cta {
  padding: 120px 5%;
  background: var(--primary-gradient);
  color: white;
  text-align: center;
}

.cta h2 {
  font-size: 2.5rem;
  margin-bottom: 20px;
}

.cta p {
  font-size: 1.4rem;
  margin-bottom: 40px;
  opacity: 0.9;
}

/* Footer */
footer {
  background: #0F172A;
  color: #eee;
  padding: 60px 5% 30px;
  text-align: center;
}

.footer-nav {
  display: flex;
  justify-content: center;
  gap: 30px;
  margin-bottom: 30px;
  flex-wrap: wrap;
}

.footer-nav a:hover {
  color: var(--gold);
  text-decoration: underline;
}

.copyright {
  color: #64748b;
  font-size: 0.9rem;
}

@media (max-width: 768px) {
  .hero h1 {
    font-size: 2.2rem;
  }
}