:root {
  --bg: #f7f8fb;
  --bg-accent: #e9f2ff;
  --surface: #ffffff;
  --text: #142034;
  --muted: #4d5a70;
  --primary: #0058d8;
  --primary-soft: #d8e8ff;
  --line: #dbe3f0;
  --radius: 18px;
  --shadow: 0 16px 40px rgba(12, 31, 66, 0.08);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Avenir Next", "SF Pro Display", "Segoe UI Variable", "Segoe UI", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at top right, #d7e9ff 0%, rgba(215, 233, 255, 0) 45%),
    radial-gradient(circle at left center, #edf7ef 0%, rgba(237, 247, 239, 0) 40%),
    var(--bg);
  line-height: 1.6;
}

.container {
  width: min(1060px, calc(100% - 2.4rem));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  backdrop-filter: blur(8px);
  background: rgba(247, 248, 251, 0.9);
  border-bottom: 1px solid var(--line);
  z-index: 10;
}

.header-row {
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  font-weight: 700;
  letter-spacing: 0.02em;
}

.nav {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.nav a {
  text-decoration: none;
  color: var(--muted);
  padding: 0.35rem 0.6rem;
  border-radius: 10px;
}

.nav a.active,
.nav a:hover {
  color: var(--text);
  background: var(--primary-soft);
}

.language-switch {
  display: inline-flex;
  border: 1px solid var(--line);
  border-radius: 999px;
  overflow: hidden;
}

.language-switch button {
  border: 0;
  padding: 0.3rem 0.65rem;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
}

.language-switch button.active {
  background: var(--primary);
  color: #fff;
}

main {
  padding: 3.2rem 0 4.6rem;
}

.hero,
.panel,
.app-detail {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: clamp(1.2rem, 3vw, 2.4rem);
}

.hero h1,
.panel h1,
.app-detail h1 {
  font-size: clamp(1.8rem, 5vw, 2.8rem);
  margin: 0 0 0.5rem;
  line-height: 1.2;
}

.hero p,
.panel p,
.app-detail p {
  color: var(--muted);
}

.button-row {
  margin-top: 1.2rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  text-decoration: none;
  padding: 0.62rem 1rem;
  border-radius: 12px;
  border: 1px solid var(--primary);
  color: #fff;
  background: var(--primary);
}

.btn.secondary {
  background: transparent;
  color: var(--primary);
}

.grid {
  display: grid;
  gap: 1rem;
}

.feature-grid {
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  margin-top: 1rem;
}

.feature-card,
.app-card {
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 1rem;
  background: #fbfdff;
}

.app-card h3,
.feature-card h3 {
  margin: 0;
}

.tagline {
  margin-top: 0.3rem;
  font-weight: 600;
  color: #2b436f;
}

.platform {
  font-size: 0.95rem;
}

.details-list {
  display: grid;
  gap: 0.8rem;
}

details {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 0.8rem 0.95rem;
  background: #fbfdff;
}

summary {
  font-weight: 600;
  cursor: pointer;
}

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

@media (max-width: 760px) {
  .header-row {
    flex-wrap: wrap;
    justify-content: center;
    padding: 0.65rem 0;
  }

  .nav {
    justify-content: center;
    flex-wrap: wrap;
  }
}