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

:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-text: #1e293b;
  --color-text-light: #64748b;
  --color-bg: #ffffff;
  --color-bg-alt: #f8fafc;
  --color-border: #e2e8f0;
  --font-main: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN", "Hiragino Sans", Meiryo, sans-serif;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

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

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

/* ===== Navigation ===== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s;
}

.nav.scrolled {
  border-bottom-color: var(--color-border);
}

.nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  color: var(--color-primary);
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 32px;
}

.nav-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-light);
  transition: color 0.2s;
}

.nav-links a:hover {
  color: var(--color-primary);
}

/* Mobile toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}

/* ===== Hero ===== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 120px 24px 80px;
  background: linear-gradient(135deg, #eff6ff 0%, #f8fafc 50%, #ede9fe 100%);
}

.hero-label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-primary);
  letter-spacing: 0.1em;
  margin-bottom: 16px;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 16px;
}

.hero-subtitle {
  font-size: clamp(1rem, 2.5vw, 1.25rem);
  color: var(--color-text-light);
  margin-bottom: 40px;
}

/* ===== Buttons ===== */
.btn {
  display: inline-block;
  padding: 14px 36px;
  font-size: 0.9375rem;
  font-weight: 600;
  border-radius: 8px;
  background: var(--color-primary);
  color: #fff;
  transition: background 0.2s, transform 0.2s;
}

.btn:hover {
  background: var(--color-primary-dark);
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
}

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

/* ===== Sections ===== */
.section {
  padding: 96px 24px;
}

.section-alt {
  background: var(--color-bg-alt);
}

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

.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 16px;
}

.section-lead {
  text-align: center;
  color: var(--color-text-light);
  font-size: 1.0625rem;
  margin-bottom: 48px;
}

.section-text {
  color: var(--color-text-light);
  max-width: 700px;
  margin: 0 auto;
  text-align: center;
}

/* ===== Cards (Features) ===== */
.cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.card {
  background: var(--color-bg);
  padding: 40px 28px;
  border-radius: 12px;
  border: 1px solid var(--color-border);
  text-align: center;
  transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.06);
}

.card-icon {
  font-size: 2rem;
  margin-bottom: 16px;
}

.card h3 {
  font-size: 1.125rem;
  margin-bottom: 12px;
}

.card p {
  font-size: 0.9375rem;
  color: var(--color-text-light);
  line-height: 1.7;
}

/* ===== Achievements ===== */
.achievements-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
  margin-top: 16px;
}

.achievement {
  text-align: center;
  padding: 40px 24px;
  border-radius: 12px;
  border: 1px solid var(--color-border);
  background: linear-gradient(135deg, #eff6ff, #faf5ff);
}

.achievement-icon {
  font-size: 2.5rem;
  margin-bottom: 16px;
}

.achievement h3 {
  font-size: 1.125rem;
  margin-bottom: 12px;
}

.achievement p {
  font-size: 0.9375rem;
  color: var(--color-text-light);
}

/* ===== Schedule & Activities ===== */
.schedule {
  text-align: center;
  margin-bottom: 48px;
  padding: 28px;
  border-radius: 12px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
}

.schedule-text {
  font-size: 1.25rem;
  margin-bottom: 4px;
}

.schedule-sub {
  font-size: 0.875rem;
  color: var(--color-text-light);
}

.activities-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.activity {
  background: var(--color-bg);
  padding: 32px 24px;
  border-radius: 12px;
  border: 1px solid var(--color-border);
}

.activity h3 {
  font-size: 1.0625rem;
  margin-bottom: 10px;
  color: var(--color-primary);
}

.activity p {
  font-size: 0.9375rem;
  color: var(--color-text-light);
}

/* ===== Join ===== */
.join-steps {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-bottom: 48px;
}

.step {
  text-align: center;
  max-width: 200px;
}

.step-num {
  width: 48px;
  height: 48px;
  margin: 0 auto 16px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #fff;
  font-size: 1.25rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}

.step p {
  font-size: 0.9375rem;
  color: var(--color-text-light);
}

.join-links {
  text-align: center;
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ===== Footer ===== */
.footer {
  text-align: center;
  padding: 32px 24px;
  border-top: 1px solid var(--color-border);
  font-size: 0.8125rem;
  color: var(--color-text-light);
}

/* ===== Fade-in Animation ===== */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-toggle {
    display: flex;
  }

  .nav-links {
    position: absolute;
    top: 64px;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(12px);
    flex-direction: column;
    gap: 0;
    padding: 8px 0;
    border-bottom: 1px solid var(--color-border);
    display: none;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links li a {
    display: block;
    padding: 14px 24px;
  }

  .cards,
  .achievements-grid,
  .activities-grid {
    grid-template-columns: 1fr;
  }

  .join-steps {
    flex-direction: column;
    align-items: center;
  }

  .hero {
    min-height: 80vh;
  }

  .section {
    padding: 64px 20px;
  }

  .sp-hide {
    display: none;
  }
}