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

/* ── Base ── */
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: #2C2416;
  background: #F8F7F4;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ── Nav ── */
.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 960px;
  margin: 0 auto;
  padding: 20px 32px;
}

.nav-brand {
  font-size: 1.5rem;
  font-weight: 700;
  color: #1C1B18;
  letter-spacing: 0.06em;
}

.btn-lang {
  padding: 6px 14px;
  background: transparent;
  border: 1px solid rgba(0, 0, 0, 0.10);
  border-radius: 6px;
  font-size: 0.8rem;
  font-weight: 500;
  color: #8A877F;
  cursor: pointer;
  transition: border-color 0.2s, color 0.2s;
  letter-spacing: 0.03em;
}

.btn-lang:hover {
  border-color: rgba(0, 0, 0, 0.20);
  color: #4D4B45;
}

/* ── Hero ── */
.hero {
  padding: 64px 32px 80px;
  text-align: center;
}

.hero-inner {
  max-width: 680px;
  margin: 0 auto;
}

.hero-label {
  display: inline-block;
  font-size: 1.2rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: #4F6EF7;
  margin-bottom: 20px;
}

.hero h1 {
  font-size: 2.8rem;
  font-weight: 800;
  line-height: 1.25;
  color: #1C1B18;
  margin-bottom: 24px;
  letter-spacing: -0.02em;
}

.hero-desc {
  font-size: 0.95rem;
  line-height: 1.8;
  color: #5A5549;
  max-width: 540px;
  margin: 0 auto 40px;
}

.hero-actions {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.hero-hint {
  font-size: 0.82rem;
  color: #8A877F;
  letter-spacing: 0.02em;
}

/* ── Buttons ── */
.btn-primary {
  display: inline-block;
  padding: 14px 36px;
  background: #4F6EF7;
  color: #fff;
  text-decoration: none;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  transition: background 0.2s, transform 0.15s, box-shadow 0.2s;
  box-shadow: 0 2px 8px rgba(79, 110, 247, 0.20),
              0 0 0 1px rgba(79, 110, 247, 0.08);
}

.btn-primary:hover {
  background: #3D5BD9;
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(79, 110, 247, 0.28),
              0 0 0 1px rgba(79, 110, 247, 0.12);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-primary--lg {
  padding: 16px 48px;
  font-size: 1.05rem;
  border-radius: 12px;
}

/* ── Main ── */
main {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 32px;
}

/* ── Section common ── */
.section {
  margin-bottom: 80px;
}

.section-header {
  text-align: center;
  margin-bottom: 40px;
}

.section-header h2 {
  font-size: 1.6rem;
  font-weight: 700;
  color: #1C1B18;
  margin-bottom: 8px;
}

.section-subtitle {
  font-size: 0.95rem;
  color: #8A877F;
}

/* ── Cards (Three Pillars) ── */
.cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.card {
  background: #FFFFFF;
  border: 1px solid rgba(0, 0, 0, 0.06);
  border-radius: 14px;
  padding: 28px 24px;
  transition: box-shadow 0.25s, transform 0.2s;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.03),
              0 0 0 1px rgba(0, 0, 0, 0.04);
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.06),
              0 0 0 1px rgba(0, 0, 0, 0.04);
}

.card-icon {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 16px;
}

.card--question .card-icon {
  background: #EEF1FE;
  color: #4F6EF7;
}

.card--content .card-icon {
  background: #F0EDFD;
  color: #6C5CE7;
}

.card--knowledge .card-icon {
  background: #E6F7F0;
  color: #0F9D6C;
}

.card h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: #1C1B18;
  margin-bottom: 8px;
}

.card p {
  font-size: 0.9rem;
  line-height: 1.65;
  color: #5A5549;
}

/* ── Principles ── */
.section--principles {
  background: #FFFFFF;
  margin-left: -32px;
  margin-right: -32px;
  padding: 64px 32px;
  border-top: 1px solid rgba(0, 0, 0, 0.05);
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.principles-grid {
  max-width: 960px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 48px;
}

.principle h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: #1C1B18;
  margin-bottom: 10px;
  padding-bottom: 10px;
  border-bottom: 2px solid #4F6EF7;
  display: inline-block;
}

.principle p {
  font-size: 0.92rem;
  line-height: 1.7;
  color: #4D4B45;
}

/* ── Use Cases ── */
.section--usecases {
  max-width: 960px;
  margin: 0 auto;
  padding: 64px 32px 0;
}

.usecases-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.usecase-card {
  background: #FFFFFF;
  border: 1px solid rgba(0, 0, 0, 0.06);
  border-radius: 12px;
  padding: 24px 20px;
  transition: box-shadow 0.25s, transform 0.2s;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.03),
              0 0 0 1px rgba(0, 0, 0, 0.04);
}

.usecase-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.06),
              0 0 0 1px rgba(0, 0, 0, 0.04);
}

.usecase-card h3 {
  font-size: 1rem;
  font-weight: 700;
  color: #1C1B18;
  margin-bottom: 6px;
}

.usecase-card p {
  font-size: 0.85rem;
  line-height: 1.6;
  color: #5A5549;
}

.usecase-card--explore {
  border-style: dashed;
  border-color: rgba(0, 0, 0, 0.12);
  background: #FAFAF8;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.usecase-card--explore h3 {
  color: #8A877F;
}

.usecase-card--explore p {
  color: #B5B2AA;
}

/* ── Presets ── */
.section--presets {
  max-width: 960px;
  margin: 0 auto;
  padding: 64px 32px 80px;
}

.presets-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.preset-card {
  background: #FFFFFF;
  border: 1px solid rgba(0, 0, 0, 0.06);
  border-radius: 12px;
  padding: 22px 20px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  transition: box-shadow 0.25s, transform 0.2s;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.03),
              0 0 0 1px rgba(0, 0, 0, 0.04);
}

.preset-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.06),
              0 0 0 1px rgba(0, 0, 0, 0.04);
}

.preset-card h3 {
  font-size: 1rem;
  font-weight: 700;
  color: #1C1B18;
}

.preset-card p {
  font-size: 0.85rem;
  line-height: 1.5;
  color: #5A5549;
}

.preset-tag {
  font-size: 0.75rem;
  color: #4F6EF7;
  font-weight: 500;
  margin-top: auto;
}

.preset-card--coming {
  border-style: dashed;
  border-color: rgba(0, 0, 0, 0.12);
  background: #FAFAF8;
  align-items: center;
  justify-content: center;
  text-align: center;
}

.preset-card--coming h3 {
  color: #8A877F;
}

.preset-card--coming p {
  color: #B5B2AA;
}

/* ── Privacy ── */
.section--privacy {
  text-align: center;
  padding-top: 16px;
}

.privacy-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 20px;
  background: #E6F7F0;
  border-radius: 100px;
  font-size: 0.88rem;
  font-weight: 600;
  color: #0F9D6C;
  margin-bottom: 32px;
}

.badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: #0F9D6C;
}

.privacy-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  max-width: 720px;
  margin: 0 auto;
}

.privacy-item {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.privacy-item strong {
  font-size: 1rem;
  font-weight: 700;
  color: #1C1B18;
}

.privacy-item span {
  font-size: 0.85rem;
  color: #8A877F;
  line-height: 1.5;
}

/* ── Footer ── */
footer {
  text-align: center;
  padding: 72px 32px 80px;
  background: #F8F7F4;
  margin-top: 80px;
  border-top: none;
}

.footer-inner {
  max-width: 480px;
  margin: 0 auto;
}

footer h2 {
  font-size: 1.8rem;
  font-weight: 700;
  color: #1C1B18;
  margin-bottom: 28px;
  line-height: 1.35;
}

footer .btn-primary {
  margin-bottom: 20px;
  display: block;
  width: fit-content;
  margin-left: auto;
  margin-right: auto;
}

.footer-note {
  font-size: 0.82rem;
  color: #8A877F;
  letter-spacing: 0.04em;
}

/* ── Responsive ── */
@media (max-width: 768px) {
  .nav {
    padding: 16px 20px;
  }

  .hero {
    padding: 40px 20px 56px;
  }

  .hero h1 {
    font-size: 1.9rem;
  }

  .hero-desc {
    font-size: 1rem;
  }

  main {
    padding: 0 20px;
  }

  .section {
    margin-bottom: 56px;
  }

  .cards {
    grid-template-columns: 1fr;
    gap: 14px;
  }

  .section--principles {
    margin-left: -20px;
    margin-right: -20px;
    padding: 40px 20px;
  }

  .principles-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .privacy-grid {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .section--usecases {
    padding: 40px 20px 0;
  }

  .usecases-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .presets-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }

  footer {
    padding: 48px 20px 56px;
    margin-top: 56px;
  }

  footer h2 {
    font-size: 1.4rem;
  }
}