/* ==================================================
   Koyuki's Picture Puzzle — Main Stylesheet
   Design System + Responsive Layout
   ================================================== */

@import url('https://fonts.googleapis.com/css2?family=Nunito:wght@400;600;700;800;900&display=swap');

/* --- CSS Variables / Design Tokens --- */
:root {
  --primary:      #8B5CF6;
  --primary-dark: #6D28D9;
  --accent:       #F472B6;
  --accent-light: #FBCFE8;
  --bg-dark:      #0D0B1A;
  --bg-card:      #1A1730;
  --bg-card2:     #221E3A;
  --text:         #F5F3FF;
  --text-sub:     #A89FC2;
  --border:       rgba(139,92,246,0.2);
  --glow:         rgba(139,92,246,0.4);
  --glow-pink:    rgba(244,114,182,0.35);
  --radius:       16px;
  --radius-sm:    10px;
  --transition:   0.3s ease;
  --max-width:    1140px;
}

/* --- Reset & Base --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Nunito', sans-serif;
  background-color: var(--bg-dark);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }

/* --- Typography --- */
h1,h2,h3,h4 { font-weight: 800; line-height: 1.2; }
h1 { font-size: clamp(2.4rem, 6vw, 4.5rem); }
h2 { font-size: clamp(1.8rem, 4vw, 2.8rem); }
h3 { font-size: 1.3rem; }
p  { color: var(--text-sub); }

.gradient-text {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.section-label {
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.75rem;
}

/* --- Layout --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}
section { padding: 100px 0; }

/* ================================================
   NAVIGATION
   ================================================ */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  padding: 1rem 0;
  transition: background var(--transition), box-shadow var(--transition);
}
.nav.scrolled {
  background: rgba(13,11,26,0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 1px 0 var(--border);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-logo {
  font-size: 1.2rem;
  font-weight: 900;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  white-space: nowrap;
}
.nav-links {
  display: flex;
  gap: 2rem;
  align-items: center;
}
.nav-links a {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-sub);
  transition: color var(--transition);
}
.nav-links a:hover { color: var(--text); }
.nav-cta {
  background: linear-gradient(135deg, var(--primary), var(--accent)) !important;
  -webkit-background-clip: unset !important;
  -webkit-text-fill-color: var(--text) !important;
  background-clip: unset !important;
  color: #fff !important;
  padding: 0.5rem 1.3rem;
  border-radius: 50px;
  font-size: 0.9rem !important;
  transition: opacity var(--transition), transform var(--transition) !important;
}
.nav-cta:hover { opacity: 0.88; transform: translateY(-1px); }

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  background: none;
  border: none;
  padding: 4px;
}
.hamburger span {
  display: block;
  width: 26px; height: 2.5px;
  background: var(--text);
  border-radius: 4px;
  transition: var(--transition);
}
.hamburger.open span:nth-child(1) { transform: translateY(7.5px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: translateY(-7.5px) rotate(-45deg); }

/* Mobile nav */
.mobile-nav {
  display: none;
  flex-direction: column;
  gap: 0;
  background: rgba(13,11,26,0.97);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-top: 1px solid var(--border);
  padding: 1rem 0;
}
.mobile-nav.open { display: flex; }
.mobile-nav a {
  padding: 0.85rem 1.5rem;
  font-weight: 600;
  color: var(--text-sub);
  border-bottom: 1px solid var(--border);
  transition: color var(--transition), background var(--transition);
}
.mobile-nav a:hover { color: var(--text); background: var(--bg-card); }
.mobile-nav a:last-child { border: none; color: var(--accent); }

/* ================================================
   HERO
   ================================================ */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  padding: 140px 0 80px;
}
.hero-bg {
  position: absolute;
  inset: 0;
  background-image: url('assets/hero.jpg');
  background-size: cover;
  background-position: center top;
  filter: brightness(0.28) saturate(1.2);
  z-index: 0;
}
.hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    rgba(109,40,217,0.45) 0%,
    rgba(13,11,26,0.55) 50%,
    rgba(244,114,182,0.25) 100%
  );
  z-index: 1;
}
.hero-content {
  position: relative;
  z-index: 2;
  max-width: 700px;
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: rgba(139,92,246,0.18);
  border: 1px solid var(--border);
  border-radius: 50px;
  padding: 0.4rem 1rem;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-light);
  margin-bottom: 1.5rem;
  backdrop-filter: blur(8px);
}
.hero h1 { margin-bottom: 1.25rem; }
.hero p {
  font-size: 1.15rem;
  color: rgba(245,243,255,0.8);
  max-width: 560px;
  margin-bottom: 2.5rem;
}
.hero-cta {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  align-items: center;
}
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  font-family: 'Nunito', sans-serif;
  font-size: 1.05rem;
  font-weight: 800;
  padding: 0.9rem 2rem;
  border-radius: 50px;
  border: none;
  cursor: pointer;
  text-decoration: none;
  box-shadow: 0 0 30px var(--glow), 0 0 10px var(--glow-pink);
  transition: transform var(--transition), box-shadow var(--transition), opacity var(--transition);
  position: relative;
  overflow: hidden;
}
.btn-primary::before {
  content: '';
  position: absolute;
  top: 0; left: -100%;
  width: 100%; height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.22), transparent);
  transition: left 0.5s ease;
}
.btn-primary:hover::before { left: 100%; }
.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 0 45px var(--glow), 0 0 20px var(--glow-pink);
}
.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-sub);
  font-weight: 700;
  font-size: 1rem;
  padding: 0.9rem 1.5rem;
  border-radius: 50px;
  border: 1px solid var(--border);
  transition: color var(--transition), border-color var(--transition), background var(--transition);
  text-decoration: none;
}
.btn-secondary:hover {
  color: var(--text);
  border-color: var(--primary);
  background: rgba(139,92,246,0.08);
}
.play-badge-img {
  height: 52px;
  width: auto;
  border-radius: 8px;
  transition: transform var(--transition), opacity var(--transition);
  filter: brightness(1.05);
}
.play-badge-img:hover { transform: translateY(-2px); opacity: 0.9; }
.hero-scroll {
  position: absolute;
  bottom: 2.5rem;
  left: 50%;
  transform: translateX(-50%);
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.4rem;
  color: var(--text-sub);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  animation: fadeInUp 1s ease 1.5s both;
}
.scroll-dot {
  width: 6px; height: 6px;
  background: var(--accent);
  border-radius: 50%;
  animation: bounce 1.4s ease infinite;
}

/* ================================================
   ABOUT / DESCRIPTION
   ================================================ */
.about {
  background: linear-gradient(180deg, var(--bg-dark) 0%, var(--bg-card) 100%);
}
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 5rem;
  align-items: center;
}
.about-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
  margin-top: 2.5rem;
}
.stat-card {
  background: var(--bg-card2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  text-align: center;
  transition: transform var(--transition), border-color var(--transition);
}
.stat-card:hover { transform: translateY(-4px); border-color: var(--primary); }
.stat-card .num {
  font-size: 2.2rem;
  font-weight: 900;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.stat-card p { font-size: 0.9rem; margin-top: 0.2rem; }
.about-visual {
  position: relative;
  display: flex;
  justify-content: center;
}
.phone-mockup {
  width: 260px;
  height: 520px;
  background: var(--bg-card2);
  border: 2px solid var(--border);
  border-radius: 38px;
  overflow: hidden;
  box-shadow: 0 0 60px rgba(139,92,246,0.25), 0 0 20px rgba(244,114,182,0.15);
  position: relative;
}
.phone-mockup-inner {
  width: 100%;
  height: 100%;
  background: linear-gradient(160deg, #1e1b2e 0%, #2d1b4e 50%, #1a1030 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 1rem;
}
.puzzle-grid-demo {
  display: grid;
  grid-template-columns: repeat(3, 70px);
  grid-template-rows: repeat(3, 70px);
  gap: 3px;
  opacity: 0.9;
}
.puzzle-cell {
  border-radius: 6px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  transition: transform 0.3s ease;
}
.puzzle-cell.filled { background: linear-gradient(135deg, var(--primary-dark), var(--accent)); }
.puzzle-cell:nth-child(odd).filled { background: linear-gradient(135deg, var(--accent), var(--primary)); }
.phone-glow {
  position: absolute;
  width: 260px; height: 260px;
  background: radial-gradient(circle, rgba(139,92,246,0.3), transparent 70%);
  top: 50%;
  left: 50%;
  transform: translate(-50%,-50%);
  z-index: -1;
}

/* ================================================
   FEATURES
   ================================================ */
.features { background: var(--bg-card); }
.features-header { text-align: center; max-width: 640px; margin: 0 auto 4rem; }
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}
.feature-card {
  background: var(--bg-dark);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  position: relative;
  overflow: hidden;
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
}
.feature-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  opacity: 0;
  transition: opacity var(--transition);
}
.feature-card:hover::before { opacity: 1; }
.feature-card:hover {
  transform: translateY(-6px);
  border-color: var(--primary);
  box-shadow: 0 16px 40px rgba(139,92,246,0.15);
}
.feature-icon {
  font-size: 2.5rem;
  margin-bottom: 1.2rem;
}
.feature-card h3 { margin-bottom: 0.6rem; color: var(--text); }
.feature-card p { font-size: 0.95rem; }

/* ================================================
   SCREENSHOTS
   ================================================ */
.screenshots { background: var(--bg-dark); }
.screenshots-header { text-align: center; max-width: 640px; margin: 0 auto 3.5rem; }
.screenshots-strip {
  display: flex;
  gap: 1.5rem;
  overflow-x: auto;
  padding: 1rem 0.5rem 2rem;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
  scrollbar-color: var(--primary) transparent;
}
.screenshots-strip::-webkit-scrollbar { height: 5px; }
.screenshots-strip::-webkit-scrollbar-thumb { background: var(--primary); border-radius: 10px; }
.screenshot-frame {
  flex: 0 0 240px;
  height: 430px;
  border-radius: 28px;
  overflow: hidden;
  border: 1.5px solid var(--border);
  box-shadow: 0 8px 32px rgba(139,92,246,0.18);
  scroll-snap-align: start;
  transition: transform var(--transition);
  position: relative;
  background: var(--bg-card2);
}
.screenshot-frame:hover { transform: scale(1.03); }
.screenshot-content {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.8rem;
  font-size: 0.8rem;
  color: var(--text-sub);
  font-weight: 600;
}
.screen-label {
  position: absolute;
  bottom: 0; left: 0; right: 0;
  background: linear-gradient(0deg, rgba(13,11,26,0.95), transparent);
  padding: 2rem 1rem 1rem;
  font-size: 0.85rem;
  font-weight: 700;
  text-align: center;
  color: var(--text);
}
/* Simulated UI for screens */
.sim-home { background: linear-gradient(160deg, #1e1b2e, #3b1f5a); }
.sim-puzzle { background: linear-gradient(160deg, #1a1030, #2d1b4e); }
.sim-gallery { background: linear-gradient(160deg, #1e2a1e, #2a3d2a); }
.sim-settings { background: linear-gradient(160deg, #1a1a2e, #16213e); }

.sim-title { font-size: 1.4rem; font-weight: 900; color: var(--text); letter-spacing: -0.02em; text-align: center; padding: 0 1rem; }
.sim-grid { display: grid; grid-template-columns: repeat(3,52px); gap:4px; }
.sim-cell { width:52px;height:52px;border-radius:8px;background:rgba(139,92,246,0.3);border:1px solid var(--border); }
.sim-cell.filled { background: linear-gradient(135deg,var(--primary),var(--accent)); }
.sim-thumb { display:grid;grid-template-columns:1fr 1fr;gap:6px;padding:0 1rem;width:100%; }
.sim-thumb-card { height:70px;border-radius:10px;background:rgba(139,92,246,0.2);border:1px solid var(--border); }
.sim-thumb-card.done { background:linear-gradient(135deg,var(--primary-dark),var(--accent)); }
.sim-tag { display:inline-block;background:rgba(244,114,182,0.2);border:1px solid var(--glow-pink);border-radius:50px;padding:0.3rem 0.9rem;font-size:0.7rem;font-weight:700;color:var(--accent);margin-bottom:0.5rem; }

/* ================================================
   CTA SECTION
   ================================================ */
.cta-section {
  background: linear-gradient(135deg, rgba(109,40,217,0.15), rgba(244,114,182,0.1));
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  text-align: center;
}
.cta-section h2 { margin-bottom: 1rem; }
.cta-section p { margin-bottom: 2.5rem; }
.cta-buttons { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; align-items: center; }

/* ================================================
   FOOTER
   ================================================ */
footer {
  background: var(--bg-card);
  border-top: 1px solid var(--border);
  padding: 4rem 0 2rem;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 3rem;
  padding-bottom: 3rem;
  border-bottom: 1px solid var(--border);
}
.footer-brand .nav-logo { font-size: 1.5rem; margin-bottom: 1rem; display: block; }
.footer-brand p { font-size: 0.9rem; max-width: 300px; }
.footer-links h4 {
  font-size: 0.85rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text);
  margin-bottom: 1.2rem;
}
.footer-links li { margin-bottom: 0.7rem; }
.footer-links a {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-sub);
  transition: color var(--transition);
}
.footer-links a:hover { color: var(--accent); }
.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 2rem;
  flex-wrap: wrap;
  gap: 1rem;
}
.footer-bottom p { font-size: 0.85rem; }

/* ================================================
   PAGE HEADERS (inner pages)
   ================================================ */
.page-header {
  padding: 140px 0 60px;
  background: linear-gradient(135deg, rgba(109,40,217,0.15), var(--bg-dark));
  border-bottom: 1px solid var(--border);
}
.page-header h1 { font-size: clamp(1.8rem, 4vw, 3rem); margin-bottom: 0.5rem; }
.page-header p { font-size: 1rem; }

/* ================================================
   CONTENT PAGES (Privacy, Terms, Contact)
   ================================================ */
.content-body {
  padding: 80px 0 100px;
  max-width: 800px;
  margin: 0 auto;
}
.content-body h2 {
  font-size: 1.5rem;
  color: var(--text);
  margin: 2.5rem 0 0.8rem;
}
.content-body h2:first-child { margin-top: 0; }
.content-body p, .content-body li {
  color: var(--text-sub);
  font-size: 0.98rem;
  margin-bottom: 0.9rem;
}
.content-body ul { padding-left: 1.5rem; list-style: disc; }
.content-body a { color: var(--accent); text-decoration: underline; }
.content-body .meta {
  font-size: 0.85rem;
  color: var(--text-sub);
  margin-bottom: 2rem;
  padding: 1rem 1.5rem;
  background: var(--bg-card);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}
.policy-page .policy-intro {
  margin-bottom: 2rem;
}
.policy-highlight-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin: 2rem 0;
}
.policy-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
}
.policy-card h3 {
  font-size: 1rem;
  color: var(--text);
  margin-bottom: 0.45rem;
}
.policy-card p {
  margin-bottom: 0;
  font-size: 0.95rem;
}
.policy-notice {
  margin: 0 0 2rem;
  padding: 1rem 1.2rem;
  border: 1px solid rgba(244,114,182,0.25);
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, rgba(244,114,182,0.12), rgba(139,92,246,0.08));
  color: var(--text-sub);
}
.policy-notice strong {
  color: var(--text);
}
.contact-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
  margin-top: 1.5rem;
}
.contact-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.8rem;
  transition: border-color var(--transition), transform var(--transition);
}
.contact-card:hover { border-color: var(--primary); transform: translateY(-3px); }
.contact-card .icon { font-size: 1.8rem; margin-bottom: 0.75rem; }
.contact-card h3 { font-size: 1rem; margin-bottom: 0.4rem; }
.contact-card a { color: var(--accent); text-decoration: none; font-weight: 600; word-break: break-all; }
.contact-card a:hover { text-decoration: underline; }

/* ================================================
   ANIMATIONS
   ================================================ */
@keyframes bounce {
  0%, 100% { transform: translateY(0); }
  50%       { transform: translateY(-6px); }
}
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes float {
  0%, 100% { transform: translateY(0); }
  50%       { transform: translateY(-12px); }
}
.fade-in { opacity: 0; transform: translateY(30px); transition: opacity 0.7s ease, transform 0.7s ease; }
.fade-in.visible { opacity: 1; transform: translateY(0); }
.float-anim { animation: float 5s ease-in-out infinite; }

/* ================================================
   RESPONSIVE
   ================================================ */
@media (max-width: 900px) {
  .nav-links { display: none; }
  .hamburger { display: flex; }
  .about-grid { grid-template-columns: 1fr; gap: 3rem; }
  .about-visual { display: none; }
  .features-grid { grid-template-columns: 1fr 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 640px) {
  section { padding: 70px 0; }
  .features-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: 2rem; }
  .footer-bottom { flex-direction: column; text-align: center; }
  .hero { padding: 120px 0 80px; }
  .contact-cards { grid-template-columns: 1fr; }
  .about-stats { grid-template-columns: 1fr 1fr; }
  .cta-buttons { flex-direction: column; }
  .policy-highlight-grid { grid-template-columns: 1fr; }
}