/* Steam風カラーパレット */
:root {
  --steam-brown-50: #F6F0EA;
  --steam-brown-100: #EADFCC;
  --steam-brown-200: #D6BE9D;
  --steam-brown-300: #C09A6B;
  --steam-brown-400: #A87945;
  --steam-brown-500: #8C5C2E;
  --steam-brown-600: #6F4622;
  --steam-brown-700: #58371B;
  --steam-brown-800: #3D2411;
  --steam-brown-900: #2A190C;
  
  --steam-gold-50: #FFF9E6;
  --steam-gold-100: #FFF1BF;
  --steam-gold-200: #FFE480;
  --steam-gold-300: #FFD74A;
  --steam-gold-400: #FFC626;
  --steam-gold-500: #E0A800;
  --steam-gold-600: #B88700;
  --steam-gold-700: #8F6900;
  --steam-gold-800: #6B4E00;
  --steam-gold-900: #4D3700;
  
  --steam-iron-50: #F2F3F5;
  --steam-iron-100: #E2E6EA;
  --steam-iron-200: #C8CED6;
  --steam-iron-300: #A6AFBD;
  --steam-iron-400: #8591A2;
  --steam-iron-500: #697483;
  --steam-iron-600: #515A66;
  --steam-iron-700: #3E4550;
  --steam-iron-800: #2C3139;
  --steam-iron-900: #1F232A;
  
  --bg: #0f0f10;
  --fg: #eae6df;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
  overflow-x: hidden;
}

/* スプラッシュスクリーン */
.splash-screen {
  position: fixed;
  inset: 0;
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--steam-gold-400);
  transition: opacity 0.5s ease-out;
}

.splash-screen.fade {
  opacity: 0;
  pointer-events: none;
}

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

.splash-loading {
  margin: 0 auto;
  height: 6rem;
  width: auto;
}

.splash-text {
  margin-top: 0.5rem;
  font-size: 0.75rem;
  color: var(--steam-brown-900);
  font-weight: 600;
}

/* 背景画像 */
.hero-background {
  position: fixed;
  inset: 0;
  z-index: 0;
  height: 100%;
  width: 100%;
  background-image: url('../images/background.png');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  background-color: var(--steam-iron-900);
}

/* メインコンテンツ */
.main-content {
  position: relative;
  z-index: 10;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

@media (min-width: 768px) {
  .container {
    padding: 0 2rem;
  }
}

/* ヒーローセクション */
.hero-section {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem 0;
}

.hero-container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.hero-content {
  text-align: center;
  position: relative;
  z-index: 20;
}

.hero-title {
  margin: 0 auto;
  height: 7rem;
  width: auto;
  max-width: 100%;
}

@media (min-width: 768px) {
  .hero-title {
    height: 9rem;
  }
}

@media (min-width: 1024px) {
  .hero-title {
    height: 10rem;
  }
}

.hero-description {
  margin-top: 1.5rem;
  margin-left: auto;
  margin-right: auto;
  max-width: 42rem;
  color: #ffffff;
  font-size: 1rem;
  line-height: 1.8;
  font-weight: 500;
  text-shadow: 
    2px 2px 4px rgba(0, 0, 0, 0.8),
    0 0 8px rgba(0, 0, 0, 0.6),
    0 0 16px rgba(0, 0, 0, 0.4);
  background: rgba(0, 0, 0, 0.3);
  padding: 1rem 1.5rem;
  border-radius: 8px;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

@media (min-width: 768px) {
  .hero-description {
    font-size: 1.125rem;
    padding: 1.25rem 2rem;
  }
}

.hero-buttons {
  margin-top: 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  justify-content: center;
}

@media (min-width: 768px) {
  .hero-buttons {
    flex-direction: row;
  }
}

.hero-mio-container {
  margin-top: 2rem;
}

.hero-mio {
  pointer-events: none;
  margin: 0 auto;
  display: block;
  height: auto;
  max-height: 60vh;
  max-width: 100%;
  width: auto;
  user-select: none;
  animation: mioFloatFade 1800ms ease-out both;
}

@keyframes mioFloatFade {
  0% {
    transform: translateY(6px) scale(0.98);
    opacity: 0;
  }
  40% {
    opacity: 1;
  }
  100% {
    transform: translateY(0) scale(1);
  }
}

/* ボタン */
.btn {
  border-radius: 4px;
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  text-decoration: none;
  display: inline-block;
  transition: all 0.2s;
  font-weight: 600;
  border: none;
  cursor: pointer;
}

.btn-primary {
  background: var(--steam-gold-500);
  color: #000;
}

.btn-primary:hover {
  background: var(--steam-gold-400);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(255, 198, 38, 0.3);
}

.btn-secondary {
  border: 1px solid var(--steam-gold-500);
  padding: 0.75rem 1.5rem;
  color: var(--steam-gold-200);
  background: transparent;
}

.btn-secondary:hover {
  background: var(--steam-iron-800);
  color: var(--steam-gold-300);
  transform: translateY(-2px);
}

.btn-large {
  padding: 1rem 2rem;
  font-size: 1.125rem;
}

/* セクションタイトル */
.section-title {
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  color: var(--steam-gold-300);
  margin-bottom: 3rem;
}

@media (min-width: 768px) {
  .section-title {
    font-size: 2.5rem;
  }
}

/* 機能紹介セクション */
.features-section {
  position: relative;
  z-index: 10;
  padding: 4rem 0;
  background: rgba(31, 35, 42, 0.95);
  backdrop-filter: blur(10px);
}

.features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}

@media (min-width: 768px) {
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .features-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.feature-card {
  border-radius: 8px;
  border: 1px solid var(--steam-iron-800);
  background: rgba(31, 35, 42, 0.9);
  padding: 2rem;
  transition: all 0.3s;
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--steam-gold-500);
  box-shadow: 0 8px 24px rgba(255, 198, 38, 0.2);
}

.feature-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.feature-title {
  margin-bottom: 0.75rem;
  color: var(--steam-gold-300);
  font-weight: 600;
  font-size: 1.25rem;
}

.feature-text {
  color: var(--steam-iron-200);
  font-size: 0.95rem;
  line-height: 1.7;
}

/* 使い方セクション */
.how-it-works-section {
  position: relative;
  z-index: 10;
  padding: 4rem 0;
  background: rgba(15, 15, 16, 0.95);
}

.steps {
  display: flex;
  flex-direction: column;
  gap: 2rem;
  max-width: 800px;
  margin: 0 auto;
}

.step {
  display: flex;
  gap: 1.5rem;
  align-items: flex-start;
}

.step-number {
  flex-shrink: 0;
  width: 3rem;
  height: 3rem;
  border-radius: 50%;
  background: var(--steam-gold-500);
  color: #000;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  font-weight: 700;
}

.step-content {
  flex: 1;
}

.step-title {
  color: var(--steam-gold-300);
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.step-text {
  color: var(--steam-iron-200);
  line-height: 1.7;
}

/* カードゲームセクション */
.card-game-section {
  position: relative;
  z-index: 10;
  padding: 4rem 0;
  background: rgba(31, 35, 42, 0.95);
}

.card-game-content {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
  align-items: center;
}

@media (min-width: 768px) {
  .card-game-content {
    grid-template-columns: 1fr 1fr;
  }
}

.card-game-video {
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.5);
}

.card-game-video video {
  width: 100%;
  height: auto;
  display: block;
}

.card-game-text {
  padding: 1rem;
}

.card-game-title {
  color: var(--steam-gold-300);
  font-size: 1.75rem;
  font-weight: 600;
  margin-bottom: 1rem;
}

.card-game-description {
  color: var(--steam-iron-200);
  line-height: 1.8;
  font-size: 1rem;
}

/* CTAセクション */
.cta-section {
  position: relative;
  z-index: 10;
  padding: 6rem 0;
  background: linear-gradient(135deg, rgba(255, 198, 38, 0.1) 0%, rgba(224, 168, 0, 0.1) 100%);
}

.cta-content {
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.cta-title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--steam-gold-300);
  margin-bottom: 1rem;
}

@media (min-width: 768px) {
  .cta-title {
    font-size: 2.5rem;
  }
}

.cta-description {
  font-size: 1.125rem;
  color: var(--steam-iron-200);
  margin-bottom: 2rem;
  line-height: 1.8;
}

.cta-buttons {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  justify-content: center;
}

@media (min-width: 768px) {
  .cta-buttons {
    flex-direction: row;
  }
}

/* 対象セクション */
.target-section {
  position: relative;
  z-index: 10;
  padding: 4rem 0;
  background: rgba(15, 15, 16, 0.95);
}

.target-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}

@media (min-width: 768px) {
  .target-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

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

.target-card {
  border-radius: 8px;
  border: 1px solid var(--steam-iron-800);
  background: rgba(31, 35, 42, 0.9);
  padding: 2rem;
  text-align: center;
  transition: all 0.3s;
}

.target-card:hover {
  transform: translateY(-4px);
  border-color: var(--steam-gold-500);
  box-shadow: 0 8px 24px rgba(255, 198, 38, 0.2);
}

.target-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.target-title {
  color: var(--steam-gold-300);
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
}

.target-text {
  color: var(--steam-iron-200);
  font-size: 0.95rem;
  line-height: 1.7;
}

/* StudySphereセクション */
.studysphere-section {
  position: relative;
  z-index: 10;
  padding: 4rem 0;
  background: rgba(31, 35, 42, 0.95);
}

.studysphere-content {
  max-width: 900px;
  margin: 0 auto;
}

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

.studysphere-title {
  color: var(--steam-gold-300);
  font-size: 1.75rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
}

.studysphere-description {
  color: var(--steam-iron-200);
  line-height: 1.8;
  font-size: 1rem;
  margin-bottom: 2rem;
}

.studysphere-link {
  color: var(--steam-gold-300);
  text-decoration: underline;
  transition: color 0.2s;
}

.studysphere-link:hover {
  color: var(--steam-gold-400);
}

.studysphere-benefits {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 2rem;
  align-items: center;
}

@media (min-width: 768px) {
  .studysphere-benefits {
    flex-direction: row;
    justify-content: center;
  }
}

.benefit-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--steam-iron-200);
}

.benefit-icon {
  font-size: 1.5rem;
}

.benefit-text {
  font-size: 0.95rem;
}

/* 料金セクション */
.pricing-section {
  position: relative;
  z-index: 10;
  padding: 4rem 0;
  background: rgba(15, 15, 16, 0.95);
}

.pricing-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
  max-width: 1000px;
  margin: 0 auto 2rem;
}

@media (min-width: 768px) {
  .pricing-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

.pricing-card {
  border-radius: 8px;
  border: 1px solid var(--steam-iron-800);
  background: rgba(31, 35, 42, 0.9);
  padding: 2rem;
  position: relative;
  transition: all 0.3s;
}

.pricing-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(255, 198, 38, 0.2);
}

.pricing-card.featured {
  border-color: var(--steam-gold-500);
  border-width: 2px;
}

.pricing-badge {
  position: absolute;
  top: -12px;
  right: 2rem;
  background: var(--steam-gold-500);
  color: #000;
  padding: 0.25rem 1rem;
  border-radius: 4px;
  font-size: 0.875rem;
  font-weight: 600;
}

.pricing-title {
  color: var(--steam-gold-300);
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
}

.pricing-description {
  text-align: center;
  margin-bottom: 1.5rem;
  color: var(--steam-iron-200);
  line-height: 1.8;
}

.pricing-description p {
  margin-bottom: 0.5rem;
}

.pricing-description p:last-child {
  margin-bottom: 0;
}

.pricing-features {
  list-style: none;
  margin-bottom: 2rem;
}

.pricing-features li {
  color: var(--steam-iron-200);
  margin-bottom: 0.75rem;
  padding-left: 1.5rem;
  position: relative;
}

.pricing-features li:before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.5rem;
  width: 6px;
  height: 6px;
  background: var(--steam-gold-500);
  border-radius: 50%;
}

.pricing-note {
  text-align: center;
  color: var(--steam-iron-400);
  font-size: 0.875rem;
  line-height: 1.8;
}

/* お問い合わせセクション */
.contact-section {
  position: relative;
  z-index: 10;
  padding: 4rem 0;
  background: rgba(31, 35, 42, 0.95);
}

.contact-content {
  max-width: 800px;
  margin: 0 auto;
}

.contact-description {
  text-align: center;
  color: var(--steam-iron-200);
  font-size: 1.125rem;
  margin-bottom: 3rem;
  line-height: 1.8;
}

.contact-cta {
  display: flex;
  justify-content: center;
  align-items: center;
  margin: 3rem 0;
}

.contact-cta .btn {
  display: inline-block;
}

.contact-form {
  background: rgba(15, 15, 16, 0.5);
  border-radius: 8px;
  padding: 2rem;
  margin-bottom: 2rem;
}

@media (min-width: 768px) {
  .contact-form {
    padding: 3rem;
  }
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-label {
  display: block;
  color: var(--steam-iron-200);
  font-size: 0.95rem;
  margin-bottom: 0.5rem;
  font-weight: 500;
}

.required {
  color: var(--steam-gold-400);
}

.form-input,
.form-textarea {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--steam-iron-800);
  border-radius: 4px;
  background: rgba(31, 35, 42, 0.8);
  color: var(--steam-iron-100);
  font-size: 1rem;
  font-family: inherit;
  transition: all 0.2s;
}

.form-input:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--steam-gold-500);
  box-shadow: 0 0 0 3px rgba(255, 198, 38, 0.1);
}

.form-textarea {
  resize: vertical;
  min-height: 120px;
}

.contact-info {
  text-align: center;
  padding: 2rem;
  background: rgba(15, 15, 16, 0.5);
  border-radius: 8px;
}

.contact-info-title {
  color: var(--steam-gold-300);
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 1rem;
}

.contact-info-text {
  color: var(--steam-iron-300);
  font-size: 0.95rem;
  line-height: 1.8;
}

/* フッター */
.footer {
  position: relative;
  z-index: 10;
  padding: 3rem 0;
  background: rgba(15, 15, 16, 0.95);
  border-top: 1px solid var(--steam-iron-800);
}

.footer-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2rem;
  margin-bottom: 2rem;
}

@media (min-width: 768px) {
  .footer-content {
    flex-direction: row;
    justify-content: space-between;
  }
}

.footer-logo-img {
  height: 3rem;
  width: auto;
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  align-items: center;
}

@media (min-width: 768px) {
  .footer-links {
    flex-direction: row;
  }
}

.footer-link {
  color: var(--steam-iron-300);
  text-decoration: none;
  transition: color 0.2s;
}

.footer-link:hover {
  color: var(--steam-gold-300);
}

.footer-copyright {
  text-align: center;
  padding-top: 2rem;
  border-top: 1px solid var(--steam-iron-800);
  color: var(--steam-iron-400);
  font-size: 0.875rem;
}