/* =============================================
   Underflow Landing Page — styles.css
   ============================================= */

:root {
  --bg:           #0a0a0f;
  --bg-card:      rgba(255, 255, 255, 0.03);
  --bg-card-hover:rgba(255, 255, 255, 0.055);
  --border:       rgba(255, 255, 255, 0.08);
  --border-hover: rgba(255, 255, 255, 0.14);
  --text:         #e8e8f0;
  --text-muted:   rgba(255, 255, 255, 0.45);
  --text-faint:   rgba(255, 255, 255, 0.28);
  --accent:       #e05588;
  --accent-dim:   rgba(224, 85, 136, 0.18);
  --accent-glow:  rgba(224, 85, 136, 0.12);
  --font:         'Inter', system-ui, -apple-system, sans-serif;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

/* ---- Layout ---- */

.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ---- Nav ---- */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s, background 0.3s, backdrop-filter 0.3s;
}

.nav.scrolled {
  background: rgba(10, 10, 15, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-color: var(--border);
}

.nav-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 18px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
}

.nav-links {
  display: flex;
  gap: 28px;
}

.nav-links a {
  font-size: 14px;
  font-weight: 400;
  color: var(--text-muted);
  transition: color 0.2s;
}

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

.nav-right {
  display: flex;
  align-items: center;
  gap: 16px;
}

.lang-switch {
  display: flex;
  gap: 2px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 2px;
}

.lang-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  font-family: var(--font);
  font-size: 12px;
  font-weight: 500;
  padding: 4px 10px;
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.2s;
}

.lang-btn.active {
  background: var(--accent-dim);
  color: var(--accent);
}

.lang-btn:hover:not(.active) {
  color: var(--text);
}

.nav-cta {
  font-size: 14px;
  font-weight: 500;
  color: var(--accent);
  padding: 7px 18px;
  border: 1px solid rgba(224, 85, 136, 0.35);
  border-radius: 8px;
  transition: background 0.2s, border-color 0.2s;
}

.nav-cta:hover {
  background: var(--accent-dim);
  border-color: var(--accent);
}

/* ---- Buttons ---- */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 13px 26px;
  border-radius: 10px;
  font-family: var(--font);
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  border: 1px solid transparent;
  text-decoration: none;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.btn-primary:hover {
  background: #d44a7c;
  border-color: #d44a7c;
  box-shadow: 0 0 28px rgba(224, 85, 136, 0.35);
}

.btn-ghost {
  background: transparent;
  color: var(--text-muted);
  border-color: var(--border);
}

.btn-ghost:hover {
  color: var(--text);
  border-color: var(--border-hover);
  background: var(--bg-card);
}

.btn-small {
  padding: 9px 18px;
  font-size: 13px;
  border-radius: 8px;
}

.btn-download {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 12px;
  padding: 16px 24px;
  gap: 14px;
  flex: 1;
  min-width: 220px;
  transition: border-color 0.2s, background 0.2s, box-shadow 0.2s;
}

.btn-download:hover {
  border-color: rgba(224, 85, 136, 0.4);
  background: rgba(224, 85, 136, 0.06);
  box-shadow: 0 4px 24px rgba(224, 85, 136, 0.12);
}

.btn-download.btn-disabled {
  opacity: 0.4;
  pointer-events: none;
}

.btn-os-icon {
  font-size: 22px;
  opacity: 0.85;
  flex-shrink: 0;
}

.btn-label {
  display: block;
  font-size: 15px;
  font-weight: 600;
}

.btn-note {
  display: block;
  font-size: 12px;
  color: var(--text-muted);
  font-weight: 400;
  margin-top: 2px;
}

/* ---- Hero ---- */

.hero {
  position: relative;
  padding: 160px 0 60px;
  text-align: center;
  overflow: hidden;
}

.hero-glow {
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 700px;
  height: 500px;
  background: radial-gradient(ellipse at 50% 0%, rgba(224, 85, 136, 0.14) 0%, transparent 70%);
  pointer-events: none;
}

.badge {
  display: inline-block;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid rgba(224, 85, 136, 0.25);
  border-radius: 20px;
  padding: 5px 14px;
  margin-bottom: 28px;
}

.hero-title {
  font-size: clamp(44px, 7vw, 80px);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: -0.03em;
  margin-bottom: 24px;
}

.accent { color: var(--accent); }

.hero-sub {
  font-size: clamp(16px, 2vw, 18px);
  color: var(--text-muted);
  max-width: 560px;
  margin: 0 auto 40px;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 48px;
}

.hero-platforms {
  display: flex;
  gap: 10px;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  font-size: 13px;
  color: var(--text-faint);
}

.hero-platforms .dot {
  opacity: 0.4;
}

/* ---- Hero Screenshot ---- */

.hero-screenshot {
  max-width: 900px;
  margin: 60px auto 0;
}

.hero-screenshot img {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 12px;
  border: 1px solid var(--border);
  box-shadow: 0 20px 80px rgba(224, 85, 136, 0.15), 0 0 0 1px var(--border);
}

.hero-screenshot-placeholder {
  aspect-ratio: 16 / 9;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px dashed var(--border);
  border-radius: 12px;
  color: var(--text-faint);
  font-size: 14px;
}

/* ---- Trust Strip ---- */

.trust-strip {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 64px;
  padding: 56px 24px;
  border-bottom: 1px solid var(--border);
}

.trust-item {
  text-align: center;
}

.trust-number {
  font-size: 36px;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--text);
  margin-bottom: 4px;
}

.trust-label {
  font-size: 13px;
  color: var(--text-muted);
}

/* ---- Sections ---- */

.section {
  padding: 96px 0;
}

.section-dark {
  background: rgba(255, 255, 255, 0.015);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.section-title {
  font-size: clamp(26px, 3.5vw, 38px);
  font-weight: 700;
  letter-spacing: -0.025em;
  text-align: center;
  margin-bottom: 12px;
}

.section-sub {
  font-size: 16px;
  color: var(--text-muted);
  text-align: center;
  margin-bottom: 60px;
}

/* ---- Steps Grid (How It Works) ---- */

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

.step-card {
  text-align: center;
  padding: 32px 24px;
}

.step-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 2px solid var(--accent);
  color: var(--accent);
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 20px;
}

.step-card h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--text);
}

.step-card p {
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.65;
}

/* ---- Features Grid ---- */

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

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 28px 24px;
  transition: border-color 0.25s, background 0.25s, box-shadow 0.25s;
}

.card:hover {
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
  box-shadow: 0 4px 32px rgba(0, 0, 0, 0.3);
}

.card-icon {
  margin-bottom: 16px;
  color: var(--text-muted);
}

.card-icon svg {
  width: 32px;
  height: 32px;
}

.card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--text);
}

.card p {
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.65;
}

/* ---- More Features Grid ---- */

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

.more-item {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 16px;
  border-radius: 10px;
  transition: background 0.2s;
}

.more-item:hover {
  background: var(--bg-card-hover);
}

.more-icon {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  margin-top: 2px;
  color: var(--text-muted);
}

.more-icon svg {
  width: 20px;
  height: 20px;
}

.more-item strong {
  display: block;
  font-size: 14px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 3px;
}

.more-item p {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.5;
}

/* ---- Comparison Table ---- */

.comparison-table {
  max-width: 720px;
  margin: 0 auto;
}

.comparison-row {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr;
  gap: 1px;
  border-bottom: 1px solid var(--border);
}

.comparison-row:last-child {
  border-bottom: none;
}

.comparison-header {
  border-bottom: 2px solid var(--border);
}

.comparison-cell {
  padding: 14px 16px;
  font-size: 14px;
  color: var(--text-muted);
}

.comparison-header .comparison-cell {
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-faint);
}

.comparison-label {
  font-weight: 500;
  color: var(--text);
}

.comparison-highlight {
  color: var(--accent);
  font-weight: 500;
}

.comparison-header .comparison-highlight {
  color: var(--accent);
}

/* ---- FAQ ---- */

.faq-list {
  max-width: 720px;
  margin: 0 auto;
}

.faq-item {
  border-bottom: 1px solid var(--border);
}

.faq-item:last-child {
  border-bottom: none;
}

.faq-question {
  display: block;
  padding: 20px 0;
  font-size: 16px;
  font-weight: 500;
  color: var(--text);
  cursor: pointer;
  list-style: none;
  transition: color 0.2s;
}

.faq-question::-webkit-details-marker {
  display: none;
}

.faq-question::after {
  content: '+';
  float: right;
  font-size: 20px;
  font-weight: 300;
  color: var(--text-muted);
  transition: transform 0.2s;
}

.faq-item[open] .faq-question::after {
  content: '−';
  color: var(--accent);
}

.faq-question:hover {
  color: var(--accent);
}

.faq-answer {
  padding: 0 0 20px;
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.7;
}

/* ---- Platforms Grid ---- */

.platforms-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 16px;
}

.platform-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px 16px;
  text-align: center;
  transition: border-color 0.2s, background 0.2s;
}

.platform-card:hover {
  border-color: rgba(224, 85, 136, 0.3);
  background: rgba(224, 85, 136, 0.04);
}

.platform-name {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 6px;
}

.platform-desc {
  font-size: 12px;
  color: var(--text-muted);
  line-height: 1.5;
}

/* ---- Download ---- */

.download-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 48px 40px;
  text-align: center;
}

.download-version {
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 32px;
}

.download-buttons {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 36px;
}

.download-notify {
  border-top: 1px solid var(--border);
  padding-top: 28px;
}

.download-notify p {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 16px;
}

.notify-form {
  display: flex;
  gap: 10px;
  justify-content: center;
  max-width: 420px;
  margin: 0 auto;
}

.notify-input {
  flex: 1;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 16px;
  font-family: var(--font);
  font-size: 14px;
  color: var(--text);
  outline: none;
  transition: border-color 0.2s;
}

.notify-input::placeholder {
  color: var(--text-faint);
}

.notify-input:focus {
  border-color: rgba(224, 85, 136, 0.4);
}

/* ---- Footer ---- */

.footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.footer-logo {
  font-size: 16px;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.footer-links {
  display: flex;
  gap: 24px;
}

.footer-links a {
  font-size: 14px;
  color: var(--text-muted);
  transition: color 0.2s;
}

.footer-links a:hover { color: var(--text); }

.footer-copy {
  font-size: 13px;
  color: var(--text-faint);
}

/* ---- Scroll Animations ---- */

.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ---- Responsive ---- */

@media (max-width: 900px) {
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .platforms-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .steps-grid {
    grid-template-columns: 1fr;
    max-width: 480px;
    margin: 0 auto;
  }
  .more-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .comparison-row {
    grid-template-columns: 1.2fr 0.9fr 0.9fr;
  }
  .trust-strip {
    gap: 40px;
  }
}

@media (max-width: 600px) {
  .hero { padding: 130px 0 60px; }
  .nav-links { display: none; }
  .features-grid { grid-template-columns: 1fr; }
  .platforms-grid { grid-template-columns: repeat(2, 1fr); }
  .download-card { padding: 32px 20px; }
  .download-buttons { flex-direction: column; align-items: stretch; }
  .btn-download { min-width: unset; }
  .footer-inner { flex-direction: column; text-align: center; gap: 12px; }
  .more-grid { grid-template-columns: 1fr; }
  .trust-strip {
    flex-direction: column;
    gap: 24px;
    padding: 40px 24px;
  }
  .comparison-cell {
    padding: 10px 8px;
    font-size: 13px;
  }
  .notify-form {
    flex-direction: column;
  }
  .hero-screenshot {
    margin: 40px 0 0;
  }
}