/* ============================================================
   go2gether — blue & white design system
   ============================================================ */

:root {
  --ink: #0f2557;
  --text: #334155;
  --muted: #64748b;
  --faint: #94a3b8;
  --primary: #2563eb;
  --primary-dark: #1e40af;
  --primary-soft: #60a5fa;
  --tint: #eff6ff;
  --tint-2: #dbeafe;
  --bg: #ffffff;
  --bg-alt: #f6f9ff;
  --line: #e2e8f0;
  --radius: 16px;
  --radius-lg: 20px;
  --shadow: 0 12px 32px -14px rgba(37, 99, 235, 0.22);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

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

.prose { max-width: 46em; }
.prose p { margin: 0 0 1em; font-size: 1.02rem; }
.prose p:last-child { margin-bottom: 0; }

/* ---------- top nav ---------- */

.topnav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.topnav-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 24px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--ink);
}

.brand .two {
  color: var(--primary);
  font-weight: 500;
}

.brand:hover { text-decoration: none; }

.nav-right {
  display: flex;
  align-items: center;
  gap: 20px;
}

.nav-links {
  display: flex;
  gap: 26px;
}

.nav-links a {
  font-size: 0.95rem;
  color: var(--text);
  transition: color 0.15s ease;
}

.nav-links a:hover {
  color: var(--primary);
  text-decoration: none;
}

.nav-links a.active {
  color: var(--primary);
  font-weight: 600;
}

.lang-toggle {
  display: flex;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #fff;
  overflow: hidden;
}

.lang-btn {
  border: 0;
  background: transparent;
  padding: 6px 14px;
  font-family: inherit;
  font-size: 0.8rem;
  line-height: 1.4;
  color: var(--muted);
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease;
}

.lang-btn.active {
  background: var(--primary);
  color: #fff;
  font-weight: 600;
}

/* ---------- hero ---------- */

.hero {
  padding: 96px 0 84px;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
}

.eyebrow {
  display: inline-block;
  margin: 0 0 18px;
  padding: 6px 14px;
  background: var(--tint);
  color: var(--primary-dark);
  border: 1px solid var(--tint-2);
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.hero h1 {
  margin: 0 0 18px;
  font-size: clamp(2.6rem, 6vw, 3.8rem);
  line-height: 1.12;
  letter-spacing: -0.02em;
  font-weight: 700;
  color: var(--ink);
}

.hero .tagline {
  margin: 0 0 34px;
  font-size: 1.13rem;
  color: var(--muted);
  max-width: 34em;
}

.hero-ill {
  width: 100%;
  max-width: 480px;
  margin: 0 auto;
}

/* ---------- buttons ---------- */

.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.btn {
  display: inline-block;
  padding: 13px 30px;
  border-radius: 999px;
  font-size: 0.98rem;
  font-weight: 600;
  transition: transform 0.16s ease, box-shadow 0.16s ease, background 0.16s ease,
    color 0.16s ease;
}

.btn-primary {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 8px 20px -8px rgba(37, 99, 235, 0.55);
}

.btn-primary:hover {
  background: var(--primary-dark);
  color: #fff;
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: 0 12px 26px -10px rgba(37, 99, 235, 0.6);
}

.btn-ghost {
  background: #fff;
  color: var(--primary-dark);
  border: 1px solid var(--tint-2);
}

.btn-ghost:hover {
  color: var(--primary);
  border-color: var(--primary-soft);
  text-decoration: none;
  transform: translateY(-2px);
}

/* ---------- sections ---------- */

.section {
  padding: 88px 0;
}

.section-alt {
  background: var(--bg-alt);
}

.section-head {
  margin-bottom: 44px;
}

.section-head .eyebrow {
  margin-bottom: 14px;
}

.section-head h2 {
  margin: 0 0 12px;
  font-size: 2.1rem;
  letter-spacing: -0.02em;
  font-weight: 700;
  color: var(--ink);
}

.section-head .sub {
  margin: 0;
  font-size: 1.05rem;
  color: var(--muted);
  max-width: 36em;
}

.section-head.center {
  text-align: center;
}

.section-head.center .sub {
  margin: 0 auto;
}

.chips.center {
  justify-content: center;
}

/* ---------- skill cards ---------- */

.cards-skill {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px 26px;
  transition: transform 0.18s ease, border-color 0.18s ease, box-shadow 0.18s ease;
}

.card:hover {
  transform: translateY(-4px);
  border-color: var(--tint-2);
  box-shadow: var(--shadow);
}

.card .icon-wrap {
  width: 52px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--tint);
  border: 1px solid var(--tint-2);
  border-radius: 14px;
  margin-bottom: 18px;
}

.card .icon-wrap img {
  width: 26px;
  height: 26px;
}

.card h3 {
  margin: 0 0 8px;
  font-size: 1.08rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.card p {
  margin: 0;
  font-size: 0.93rem;
  color: var(--muted);
}

/* ---------- app cards ---------- */

.app-card {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 36px;
  align-items: center;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 36px;
  margin-bottom: 22px;
  transition: border-color 0.18s ease, box-shadow 0.18s ease;
}

.app-card:hover {
  border-color: var(--tint-2);
  box-shadow: var(--shadow);
}

.app-ill-panel {
  background: var(--tint);
  border: 1px solid var(--tint-2);
  border-radius: var(--radius-lg);
  padding: 34px 30px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.app-ill-panel img {
  width: 100%;
  max-width: 420px;
}

.app-card.flip .app-ill-panel {
  order: 2;
}

.app-name {
  margin: 0 0 6px;
  font-size: 1.45rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.app-line {
  margin: 0 0 18px;
  font-size: 1rem;
  color: var(--muted);
}

.app-feats {
  list-style: none;
  margin: 0 0 22px;
  padding: 0;
  display: grid;
  gap: 10px;
}

.app-feats li {
  position: relative;
  padding-left: 30px;
  font-size: 0.95rem;
  color: var(--text);
}

.app-feats li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.28em;
  width: 17px;
  height: 17px;
  border-radius: 50%;
  background: var(--tint);
  border: 1px solid var(--tint-2);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 17 17'%3E%3Cpath d='M4.5 8.8 7 11.3 12.5 5.5' fill='none' stroke='%232563eb' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-size: 11px 11px;
  background-position: center;
  background-repeat: no-repeat;
}

.app-link {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--primary);
}

.app-link:hover {
  color: var(--primary-dark);
  text-decoration: none;
}

.app-link .arr {
  display: inline-block;
  transition: transform 0.15s ease;
}

.app-link:hover .arr {
  transform: translateX(4px);
}

/* ---------- CTA band ---------- */

.cta-band {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  border-radius: 24px;
  padding: 64px 48px;
  text-align: center;
  color: #fff;
  box-shadow: 0 24px 48px -20px rgba(37, 99, 235, 0.5);
}

.cta-band h2 {
  margin: 0 0 12px;
  font-size: 2rem;
  letter-spacing: -0.02em;
  color: #fff;
}

.cta-band p {
  margin: 0 auto 30px;
  max-width: 30em;
  font-size: 1.05rem;
  color: rgba(255, 255, 255, 0.85);
}

.btn-white {
  background: #fff;
  color: var(--primary-dark);
  padding: 13px 34px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 1rem;
  display: inline-block;
  transition: transform 0.16s ease, box-shadow 0.16s ease;
}

.btn-white:hover {
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: 0 12px 24px -8px rgba(15, 37, 87, 0.4);
}

/* ---------- footer ---------- */

.footer {
  border-top: 1px solid var(--line);
  padding: 42px 0 56px;
}

.footer-line {
  margin: 0 0 12px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  font-size: 0.88rem;
  color: var(--faint);
}

.footer-line .brand {
  font-size: 0.95rem;
}

.dot { color: var(--line); }

.footer-icp {
  margin: 0;
  font-size: 0.8rem;
  color: var(--faint);
}

.footer-icp a {
  color: var(--faint);
  text-decoration: none;
}

.footer-icp a:hover {
  color: var(--primary);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---------- subpages: breadcrumb + page head ---------- */

.breadcrumb {
  padding: 26px 0 0;
  margin: 0;
  font-size: 0.85rem;
  color: var(--faint);
}

.breadcrumb a {
  color: var(--faint);
}

.breadcrumb a:hover {
  color: var(--primary);
  text-decoration: none;
}

.breadcrumb .sep {
  margin: 0 8px;
  color: var(--line);
}

.page-head {
  padding: 40px 0 0;
}

.page-head h1 {
  margin: 0 0 10px;
  font-size: clamp(2.2rem, 4.6vw, 3rem);
  letter-spacing: -0.02em;
  font-weight: 700;
  color: var(--ink);
}

.page-head .sub {
  margin: 0;
  font-size: 1.15rem;
  color: var(--muted);
  max-width: 36em;
}

/* ---------- detail pages: mockup panel + features ---------- */

.mockup-panel {
  background: var(--bg-alt);
  border: 1px solid var(--line);
  border-radius: 24px;
  padding: 48px 32px;
  margin: 44px 0 64px;
  display: flex;
  justify-content: center;
}

.mockup-panel img {
  width: 100%;
  max-width: 640px;
}

.mockup-panel.panel-ios img {
  max-width: 340px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

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

.feature h3 {
  margin: 0 0 6px;
  font-size: 1rem;
  font-weight: 700;
  color: var(--ink);
}

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

.highlights {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

.highlight {
  background: var(--tint);
  border: 1px solid var(--tint-2);
  border-radius: 12px;
  padding: 14px 16px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--primary-dark);
  text-align: center;
}

.detail-prose {
  padding-top: 56px;
}

/* ---------- about ---------- */

.about-hero {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
}

.about-hero .prose p:first-child {
  font-size: 1.12rem;
  color: var(--text);
}

.values-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.chip {
  display: inline-block;
  padding: 8px 18px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text);
  transition: border-color 0.15s ease, color 0.15s ease, transform 0.15s ease;
}

.chip:hover {
  border-color: var(--primary-soft);
  color: var(--primary);
  transform: translateY(-1px);
  text-decoration: none;
}

.chip-solid {
  background: var(--tint);
  border-color: var(--tint-2);
  color: var(--primary-dark);
}

/* ---------- contact ---------- */

.contact-hero {
  text-align: center;
  max-width: 40em;
  margin: 0 auto;
}

.contact-hero .sub {
  margin-bottom: 36px;
}

.email-display {
  display: inline-block;
  margin: 0 0 20px;
  font-size: clamp(1.3rem, 3.4vw, 1.9rem);
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--ink);
  border-bottom: 2px solid var(--tint-2);
  padding-bottom: 4px;
  transition: border-color 0.15s ease, color 0.15s ease;
}

.email-display:hover {
  color: var(--primary);
  border-color: var(--primary-soft);
  text-decoration: none;
}

.contact-mail-label {
  display: block;
  margin-bottom: 8px;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--faint);
}

.flow {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.flow-step {
  position: relative;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 26px 24px;
}

.flow-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  background: var(--tint);
  border: 1px solid var(--tint-2);
  color: var(--primary-dark);
  font-weight: 700;
  font-size: 0.95rem;
  margin-bottom: 14px;
}

.flow-step h3 {
  margin: 0 0 6px;
  font-size: 1.02rem;
  font-weight: 700;
  color: var(--ink);
}

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

.contact-note {
  text-align: center;
  margin: 26px 0 0;
  font-size: 0.88rem;
  color: var(--faint);
}

/* ---------- reveal on scroll ---------- */

.reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}

.reveal.visible {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
  html {
    scroll-behavior: auto;
  }
}

/* ---------- responsive ---------- */

@media (max-width: 960px) {
  .hero {
    padding: 64px 0 56px;
  }
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .hero-ill {
    max-width: 420px;
    order: 2;
  }
  .cards-skill,
  .values-grid,
  .flow {
    grid-template-columns: 1fr 1fr;
  }
  .app-card {
    grid-template-columns: 1fr;
    padding: 28px;
    gap: 28px;
  }
  .app-card.flip .app-ill-panel {
    order: 0;
  }
  .feature-grid {
    grid-template-columns: 1fr;
  }
  .highlights {
    grid-template-columns: 1fr 1fr;
  }
  .about-hero {
    grid-template-columns: 1fr;
  }
  .about-hero .hero-ill {
    order: 2;
  }
  .section {
    padding: 64px 0;
  }
}

@media (max-width: 620px) {
  .topnav-inner {
    height: 58px;
  }
  .nav-links {
    display: none;
  }
  .cards-skill,
  .values-grid,
  .flow,
  .highlights {
    grid-template-columns: 1fr;
  }
  .cta-band {
    padding: 48px 26px;
    border-radius: 20px;
  }
  .mockup-panel {
    padding: 28px 16px;
  }
}