/* =========================
  1. Reset / Base
========================= */
*,
*::before,
*::after {
  box-sizing: border-box;
}

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

body {
  margin: 0;
  font-family: Arial, "Hiragino Sans", "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
  line-height: 1.6;
  color: #1f2430;
  background: #ffffff;
}

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

a {
  color: inherit;
}

ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

button,
input,
textarea,
select {
  font: inherit;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

:root {
  --container: 1100px;
  --text: #1f2430;
  --muted: #5e6778;
  --line: #d9dee8;
  --soft: #f7f8fb;
  --soft-2: #f1f4f8;
  --card: #ffffff;
  --accent: #1f2430;
  --shadow: 0 14px 32px rgba(31, 36, 48, 0.08);
}

/* =========================
  2. Layout
========================= */
.container {
  width: min(var(--container), calc(100% - 32px));
  margin: 0 auto;
}

.section {
  padding: 80px 0;
}

.section-soft {
  background: var(--soft);
}

.section-head {
  max-width: 760px;
  margin-bottom: 40px;
}

.section-label {
  margin: 0 0 10px;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

.section-head h2,
.start-box h2 {
  margin: 0 0 14px;
  font-size: clamp(1.8rem, 3vw, 2.6rem);
  line-height: 1.2;
}

.section-lead,
.start-box p {
  margin: 0;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.8;
}

/* =========================
  3. Header
========================= */
.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(10px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 68px;
}

.logo {
  font-weight: 800;
  text-decoration: none;
  letter-spacing: 0.01em;
}

.site-nav ul {
  display: flex;
  gap: 24px;
}

.site-nav a {
  text-decoration: none;
  color: #293042;
}

.site-nav a:hover {
  opacity: 0.75;
}

.menu-toggle {
  display: none;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #fff;
  cursor: pointer;
}

/* =========================
  4. Hero
========================= */
.hero {
  position: relative;
  min-height: 82vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  background: #edf2f7;
}

.hero-media {
  position: absolute;
  inset: 0;
}

.hero-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center center;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(
      90deg,
      rgba(18, 22, 32, 0.56) 0%,
      rgba(18, 22, 32, 0.34) 40%,
      rgba(18, 22, 32, 0.08) 100%
    );
}

.hero-inner {
  position: relative;
  z-index: 2;
  width: 100%;
}

.hero-copy {
  max-width: 620px;
  padding: 110px 0;
  padding-left: clamp(16px, 4vw, 64px);
  color: #fff;
}

.hero-label {
  margin: 0 0 12px;
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.88);
}

.hero h1 {
  margin: 0 0 18px;
  font-size: clamp(2.4rem, 5vw, 4.4rem);
  line-height: 1.12;
  font-weight: 800;
}

.hero-text {
  margin: 0 0 28px;
  font-size: 1.05rem;
  line-height: 1.85;
  color: rgba(255, 255, 255, 0.92);
}

/* =========================
  5. Components
========================= */
.btn {
  display: inline-block;
  padding: 13px 22px;
  border-radius: 999px;
  text-decoration: none;
  background: var(--accent);
  color: #fff;
  font-weight: 700;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.btn:hover {
  transform: translateY(-1px);
  opacity: 0.95;
}

.hero-btn {
  background: #ffffff;
  color: #1f2430;
}

/* Sound Map */
.sound-grid {
  display: grid;
  gap: 18px;
  grid-template-columns: repeat(4, 1fr);
}

.sound-card {
  display: flex;
  flex-direction: column;
  gap: 10px;
  min-height: 150px;
  padding: 24px 20px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: #fff;
  text-decoration: none;
  box-shadow: var(--shadow);
  transition: transform 0.2s ease, border-color 0.2s ease;
}

.sound-card:hover {
  transform: translateY(-3px);
  border-color: #bfc7d6;
}

.sound-ipa {
  font-size: 2rem;
  font-weight: 800;
  line-height: 1;
}

.sound-name {
  color: var(--muted);
  line-height: 1.6;
}

/* Steps */
.step-grid {
  display: grid;
  gap: 20px;
  grid-template-columns: repeat(4, 1fr);
}

.step-card {
  padding: 26px 22px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: #fff;
}

.step-num {
  display: inline-block;
  margin-bottom: 14px;
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.step-card h3,
.feature-card h3 {
  margin: 0 0 10px;
  font-size: 1.1rem;
}

.step-card p,
.feature-card p {
  margin: 0;
  color: var(--muted);
}

/* Features */
.feature-grid {
  display: grid;
  gap: 20px;
  grid-template-columns: repeat(3, 1fr);
}

.feature-card {
  padding: 28px 24px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: #fff;
  box-shadow: var(--shadow);
}

/* Start */
.start-section {
  background: #ffffff;
}

.start-box {
  padding: 40px;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: var(--soft-2);
  text-align: center;
}

.start-box .btn {
  margin-top: 20px;
}

/* =========================
   Start Section
========================= */
.section-start {
  padding: 80px 20px;
  background: linear-gradient(180deg, #fffaf3 0%, #ffffff 100%);
  text-align: center;
}

.start-box {
  max-width: 640px;
  margin: 0 auto;
}

.start-title {
  font-size: 32px;
  line-height: 1.4;
  margin-bottom: 20px;
  color: #2d2d2d;
}

.start-lead {
  font-size: 15px;
  line-height: 1.8;
  color: #666;
  margin-bottom: 32px;
}

.btn-start {
  display: inline-block;
  padding: 16px 32px;
  background: #ff8a3d;
  color: #fff;
  font-weight: 600;
  border-radius: 999px;
  text-decoration: none;
  transition: all 0.2s ease;
}

.btn-start:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(255, 138, 61, 0.25);
}

.start-note {
  margin-top: 16px;
  font-size: 12px;
  color: #999;
}

/* =========================
  6. Footer
========================= */
.site-footer {
  padding: 26px 0;
  border-top: 1px solid var(--line);
  background: #fff;
}

.footer-inner {
  display: flex;
  justify-content: center;
}

.site-footer p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--muted);
}

/* =========================
  7. Responsive
========================= */
@media (max-width: 1024px) {
  .sound-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .step-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .feature-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 767px) {
  .section {
    padding: 64px 0;
  }

  .site-nav {
    display: none;
  }

  .site-nav.is-open {
    display: block;
    position: absolute;
    top: 68px;
    right: 16px;
    width: min(260px, calc(100% - 32px));
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 14px;
    padding: 14px 16px;
    box-shadow: 0 14px 30px rgba(31, 36, 48, 0.12);
  }

  .site-nav.is-open ul {
    display: grid;
    gap: 12px;
  }

  .menu-toggle {
    display: inline-block;
  }

  .hero {
    min-height: 72vh;
  }

  .hero-overlay {
    background:
      linear-gradient(
        180deg,
        rgba(18, 22, 32, 0.22) 0%,
        rgba(18, 22, 32, 0.54) 100%
      );
  }

  .hero-copy {
    max-width: 100%;
    padding: 72px 0 52px;
    padding-left: 16px;
  }

  .hero h1 {
    font-size: 2.1rem;
  }

  .hero-text {
    font-size: 0.97rem;
    line-height: 1.75;
  }

  .sound-grid,
  .step-grid,
  .feature-grid {
    grid-template-columns: 1fr;
  }

  .sound-card {
    min-height: auto;
  }

  .start-box {
    padding: 28px 20px;
  }
}