/* ============================================================
   YouTube VOICEVOX LP – style.css
   Design: "Sound Wave Editorial" – bold green/yellow, clean JP
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+JP:wght@400;500;700;900&family=Syne:wght@700;800&display=swap');

/* ── Variables ───────────────────────────────────────────── */
:root {
  --green:       #51C020;
  --green-dark:  #3a8c16;
  --green-deep:  #1e4d0a;
  --green-light: #d4f5be;
  --green-pale:  #f0fcea;
  --yellow:      #F5C400;
  --yellow-light:#fffacc;
  --ink:         #111;
  --ink-mid:     #333;
  --ink-muted:   #666;
  --surface:     #fff;
  --surface-alt: #f8fdf5;
  --border:      #d8eecf;
  --radius:      12px;
  --radius-lg:   20px;
  --shadow:      0 4px 24px rgba(81,192,32,.13);
  --shadow-lg:   0 12px 48px rgba(81,192,32,.18);
  --nav-h:       64px;
  --transition:  .22s cubic-bezier(.4,0,.2,1);
  --max-w:       1160px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ink:        #f0f0f0;
    --ink-mid:    #ccc;
    --ink-muted:  #999;
    --surface:    #141a10;
    --surface-alt:#1a2413;
    --border:     #2a3d1e;
    --green-pale: #1a2e12;
    --green-light:#2a4a1a;
    --yellow-light:#2a2200;
  }
}

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

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

body {
  font-family: 'Noto Sans JP', sans-serif;
  color: var(--ink);
  background: var(--surface);
  line-height: 1.7;
  overflow-x: hidden;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--green-dark); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ── Utility ─────────────────────────────────────────────── */
.container { max-width: var(--max-w); margin: 0 auto; padding: 0 24px; }

.section-label {
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--green);
  margin-bottom: 12px;
}

.section-title {
  font-size: clamp(1.6rem, 4vw, 2.6rem);
  font-weight: 900;
  line-height: 1.25;
  color: var(--ink);
  margin-bottom: 16px;
}

.section-body {
  font-size: 1rem;
  color: var(--ink-muted);
  max-width: 600px;
}

/* ── Buttons ─────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 28px;
  border-radius: 100px;
  font-family: 'Noto Sans JP', sans-serif;
  font-weight: 700;
  font-size: .95rem;
  cursor: pointer;
  border: 2px solid transparent;
  transition: var(--transition);
  white-space: nowrap;
  text-decoration: none;
}

.btn-primary {
  background: var(--green);
  color: #fff;
  border-color: var(--green);
  box-shadow: 0 4px 20px rgba(81,192,32,.35);
}
.btn-primary:hover {
  background: var(--green-dark);
  border-color: var(--green-dark);
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(81,192,32,.45);
  text-decoration: none;
  color: #fff;
}

.btn-outline {
  background: transparent;
  color: var(--green);
  border-color: var(--green);
}
.btn-outline:hover {
  background: var(--green-pale);
  text-decoration: none;
}

.btn-sm {
  padding: 9px 18px;
  font-size: .85rem;
}

/* ── Badges ──────────────────────────────────────────────── */
.badge-row { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }

.badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 4px 12px;
  border-radius: 100px;
  font-size: .78rem;
  font-weight: 700;
  border: 1.5px solid;
}

.badge-green {
  background: var(--green-pale);
  color: var(--green-dark);
  border-color: var(--green-light);
}

.badge-yellow {
  background: var(--yellow-light);
  color: #7a5f00;
  border-color: #f5d96a;
}

/* ============================================================
   NAV
   ============================================================ */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  height: var(--nav-h);
  background: rgba(255,255,255,.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  transition: var(--transition);
}

@media (prefers-color-scheme: dark) {
  .nav { background: rgba(20,26,16,.88); }
}

.nav__inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.nav__logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 900;
  font-size: .95rem;
  color: var(--ink);
  text-decoration: none;
  flex-shrink: 0;
}
.nav__logo:hover { text-decoration: none; }

.nav__logo img {
  width: 32px;
  height: 32px;
  border-radius: 8px;
}

.nav__logo-text {
  line-height: 1.2;
  font-size: .82rem;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
}

.nav__links a {
  font-size: .88rem;
  font-weight: 500;
  color: var(--ink-mid);
  text-decoration: none;
  transition: color var(--transition);
}
.nav__links a:hover { color: var(--green); }

.nav__cta { flex-shrink: 0; }

@media (max-width: 680px) {
  .nav__links { display: none; }
  .nav__logo-text { display: none; }
}

/* ============================================================
   HERO
   ============================================================ */
.hero {
  min-height: 100vh;
  padding-top: var(--nav-h);
  background: linear-gradient(145deg, #0d2b06 0%, #1e5a0c 40%, #2d7a14 70%, #3a8c16 100%);
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: center;
}

/* Wave bars decoration */
.hero__waves {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
  opacity: .12;
  gap: 4px;
  padding: 0 5%;
}

.wave-bar {
  flex: 1;
  background: #fff;
  border-radius: 100px;
  animation: wavePulse var(--dur, 1.2s) ease-in-out infinite alternate;
  animation-delay: var(--delay, 0s);
  max-width: 6px;
}

@keyframes wavePulse {
  from { height: var(--h-low, 20px); }
  to   { height: var(--h-high, 80px); }
}

.hero__inner {
  position: relative;
  z-index: 2;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
  padding: 80px 0;
  width: 100%;
}

.hero__content { max-width: 560px; }

.hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(245,196,0,.18);
  border: 1px solid rgba(245,196,0,.4);
  color: var(--yellow);
  padding: 5px 14px;
  border-radius: 100px;
  font-size: .8rem;
  font-weight: 700;
  letter-spacing: .06em;
  margin-bottom: 24px;
}

.hero__title {
  font-family: 'Noto Sans JP', sans-serif;
  font-weight: 900;
  font-size: clamp(2rem, 5vw, 3.4rem);
  line-height: 1.15;
  color: #fff;
  margin-bottom: 20px;
  letter-spacing: -.01em;
}

.hero__title span {
  color: var(--yellow);
  display: inline;
}

.hero__sub {
  font-size: 1.05rem;
  color: rgba(255,255,255,.82);
  margin-bottom: 36px;
  line-height: 1.75;
}

.hero__cta-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  margin-bottom: 32px;
}

.hero__badges { display: flex; flex-wrap: wrap; gap: 8px; }

.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 4px 12px;
  border-radius: 100px;
  font-size: .76rem;
  font-weight: 700;
  background: rgba(255,255,255,.1);
  color: rgba(255,255,255,.9);
  border: 1px solid rgba(255,255,255,.2);
}

.hero__visual {
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
}

.hero__screenshot {
  border-radius: var(--radius-lg);
  box-shadow: 0 32px 80px rgba(0,0,0,.45);
  width: 100%;
  max-width: 520px;
  transform: perspective(1000px) rotateY(-6deg) rotateX(2deg);
  transition: transform .4s ease;
  border: 1px solid rgba(255,255,255,.08);
}

.hero__screenshot:hover {
  transform: perspective(1000px) rotateY(0deg) rotateX(0deg);
}

@media (max-width: 860px) {
  .hero__inner {
    grid-template-columns: 1fr;
    gap: 40px;
    text-align: center;
    padding: 60px 0 40px;
  }
  .hero__content { max-width: 100%; }
  .hero__cta-row { justify-content: center; }
  .hero__badges { justify-content: center; }
  .hero__screenshot { transform: none; max-width: 380px; margin: 0 auto; }
  .hero__waves { gap: 2px; }
}

/* ============================================================
   FEATURES (3-col)
   ============================================================ */
.features {
  padding: 100px 0;
  background: var(--surface);
}

.features__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  margin-top: 56px;
}

.feature-card {
  background: var(--surface-alt);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px 32px;
  position: relative;
  overflow: hidden;
  transition: var(--transition);
}

.feature-card::before {
  content: '';
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 4px;
  background: var(--green);
  border-radius: 4px 0 0 4px;
  transform: scaleY(0);
  transition: transform var(--transition);
  transform-origin: bottom;
}

.feature-card:hover {
  border-color: var(--green);
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
}
.feature-card:hover::before { transform: scaleY(1); }

.feature-card__icon {
  font-size: 2.2rem;
  margin-bottom: 20px;
  line-height: 1;
}

.feature-card__title {
  font-weight: 900;
  font-size: 1.1rem;
  color: var(--ink);
  margin-bottom: 12px;
}

.feature-card__desc {
  font-size: .9rem;
  color: var(--ink-muted);
  line-height: 1.7;
}

@media (max-width: 720px) {
  .features__grid { grid-template-columns: 1fr; }
}

/* ============================================================
   DETAIL TABS
   ============================================================ */
.detail {
  padding: 100px 0;
  background: var(--surface-alt);
}

.detail__header { margin-bottom: 48px; }

.tabs {
  display: flex;
  gap: 0;
  border-bottom: 2px solid var(--border);
  margin-bottom: 40px;
  overflow-x: auto;
  scrollbar-width: none;
}
.tabs::-webkit-scrollbar { display: none; }

.tab-btn {
  padding: 14px 28px;
  font-family: 'Noto Sans JP', sans-serif;
  font-size: .92rem;
  font-weight: 700;
  color: var(--ink-muted);
  background: none;
  border: none;
  border-bottom: 3px solid transparent;
  margin-bottom: -2px;
  cursor: pointer;
  white-space: nowrap;
  transition: var(--transition);
}
.tab-btn:hover { color: var(--green); }
.tab-btn.active {
  color: var(--green);
  border-bottom-color: var(--green);
}

.tab-panel { display: none; }
.tab-panel.active { display: block; }

.tab-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 56px;
  align-items: center;
}

.tab-content__list { list-style: none; }

.tab-content__item {
  display: flex;
  gap: 14px;
  padding: 18px 0;
  border-bottom: 1px solid var(--border);
}
.tab-content__item:last-child { border-bottom: none; }

.tab-content__icon {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  background: var(--green-pale);
  border: 1.5px solid var(--green-light);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  margin-top: 2px;
}

.tab-content__text strong {
  display: block;
  font-weight: 700;
  font-size: .95rem;
  color: var(--ink);
  margin-bottom: 4px;
}

.tab-content__text span {
  font-size: .85rem;
  color: var(--ink-muted);
}

.tab-content__img img {
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  width: 100%;
  border: 1px solid var(--border);
}

@media (max-width: 760px) {
  .tab-content { grid-template-columns: 1fr; gap: 32px; }
  .tab-content__img { order: -1; }
}

/* ============================================================
   SCREENSHOTS
   ============================================================ */
.screenshots {
  padding: 100px 0;
  background: var(--surface);
}

.screenshots__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
  margin-top: 48px;
}

.screenshot-card {
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1.5px solid var(--border);
  box-shadow: var(--shadow);
  transition: var(--transition);
  background: var(--surface-alt);
}
.screenshot-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: var(--green);
}

.screenshot-card img {
  width: 100%;
  display: block;
}

.screenshot-card__caption {
  padding: 16px 20px;
  font-size: .88rem;
  font-weight: 700;
  color: var(--ink-mid);
  display: flex;
  align-items: center;
  gap: 8px;
}
.screenshot-card__caption::before {
  content: '';
  width: 8px; height: 8px;
  background: var(--green);
  border-radius: 50%;
  flex-shrink: 0;
}

@media (max-width: 640px) {
  .screenshots__grid { grid-template-columns: 1fr; }
}

/* ============================================================
   STEPS
   ============================================================ */
.steps {
  padding: 100px 0;
  background: var(--surface-alt);
}

.steps__inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
  margin-top: 56px;
}

.steps__list { list-style: none; display: flex; flex-direction: column; gap: 32px; }

.step-item {
  display: flex;
  gap: 20px;
  align-items: flex-start;
}

.step-num {
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  background: var(--green);
  color: #fff;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 900;
  font-size: 1.1rem;
  font-family: 'Syne', sans-serif;
  box-shadow: 0 4px 16px rgba(81,192,32,.35);
}

.step-text strong {
  display: block;
  font-weight: 700;
  font-size: 1rem;
  color: var(--ink);
  margin-bottom: 6px;
}
.step-text span {
  font-size: .88rem;
  color: var(--ink-muted);
}

.steps__img {
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  border: 1.5px solid var(--border);
}
.steps__img img { width: 100%; }

@media (max-width: 760px) {
  .steps__inner { grid-template-columns: 1fr; gap: 40px; }
}

/* ============================================================
   ABOUT / CREDIT
   ============================================================ */
.about {
  padding: 80px 0;
  background: var(--surface);
  border-top: 1.5px solid var(--border);
}

.about__box {
  max-width: 720px;
  margin: 0 auto;
  text-align: center;
}

.about__title {
  font-size: 1.3rem;
  font-weight: 900;
  color: var(--ink);
  margin-bottom: 20px;
}

.about__body {
  font-size: .9rem;
  color: var(--ink-muted);
  line-height: 1.85;
  margin-bottom: 28px;
}

.about__links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
}

.about__link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 20px;
  border-radius: 100px;
  font-size: .85rem;
  font-weight: 700;
  background: var(--surface-alt);
  color: var(--ink-mid);
  border: 1.5px solid var(--border);
  text-decoration: none;
  transition: var(--transition);
}
.about__link:hover {
  border-color: var(--green);
  color: var(--green);
  background: var(--green-pale);
  text-decoration: none;
}

.about__voicevox {
  margin-top: 24px;
  padding: 20px 28px;
  background: var(--green-pale);
  border: 1.5px solid var(--green-light);
  border-radius: var(--radius);
  font-size: .85rem;
  color: var(--green-dark);
}

/* ============================================================
   FOOTER
   ============================================================ */
.footer {
  background: var(--green-deep);
  color: rgba(255,255,255,.65);
  padding: 40px 0;
}

.footer__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.footer__copy {
  font-size: .82rem;
  color: rgba(255,255,255,.5);
}

.footer__links {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  list-style: none;
}

.footer__links a {
  font-size: .82rem;
  color: rgba(255,255,255,.65);
  text-decoration: none;
  transition: color var(--transition);
}
.footer__links a:hover { color: var(--yellow); }

/* ============================================================
   Scroll reveal
   ============================================================ */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity .55s ease, transform .55s ease;
}
.reveal.visible {
  opacity: 1;
  transform: none;
}