/* ツインマーク・アリーナ Web - Neo AI Brand Theme */

:root {
  --font-body: 'Space Grotesk', 'Inter', 'Noto Sans JP', 'Hiragino Kaku Gothic ProN', 'Yu Gothic', sans-serif;
  --font-display: 'Space Grotesk', 'Noto Sans JP', sans-serif;

  --color-bg: #020617;
  --color-bg-soft: #050c1f;
  --color-panel: rgba(9, 15, 37, 0.8);
  --color-panel-strong: rgba(11, 22, 52, 0.9);
  --color-border: rgba(148, 163, 184, 0.35);
  --color-border-strong: rgba(56, 189, 248, 0.5);
  --color-text: #f8fafc;
  --color-text-soft: rgba(226, 232, 240, 0.75);
  --color-muted: rgba(148, 163, 184, 0.65);
  --color-primary: #38bdf8;
  --color-primary-strong: #0ea5e9;
  --color-secondary: #c084fc;
  --color-accent: #f472b6;

  --spacing-xs: 0.5rem;
  --spacing-sm: 0.75rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2.5rem;
  --spacing-xxl: 4rem;

  --radius-sm: 0.85rem;
  --radius-md: 1.25rem;
  --radius-lg: 1.75rem;

  --shadow-soft: 0 20px 60px rgba(2, 6, 23, 0.55);
  --shadow-card: 0 30px 80px rgba(2, 132, 199, 0.15);
}

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

body {
  font-family: var(--font-body);
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

body::before,
body::after {
  content: '';
  position: fixed;
  inset: 0;
  z-index: -2;
}

body::before {
  background: radial-gradient(circle at 15% 20%, rgba(56, 189, 248, 0.3), transparent 45%),
              radial-gradient(circle at 80% 0%, rgba(236, 72, 153, 0.25), transparent 40%),
              radial-gradient(circle at 70% 80%, rgba(192, 132, 252, 0.25), transparent 55%),
              linear-gradient(120deg, #030712 0%, #050b1b 100%);
}

body::after {
  background-image: linear-gradient(rgba(15, 23, 42, 0.25) 1px, transparent 1px),
                    linear-gradient(90deg, rgba(15, 23, 42, 0.25) 1px, transparent 1px);
  background-size: 80px 80px;
  opacity: 0.2;
  mask-image: radial-gradient(circle at center, rgba(0, 0, 0, 0.9), rgba(0, 0, 0, 0));
}

main {
  position: relative;
  z-index: 1;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(2, 6, 23, 0.8);
  backdrop-filter: blur(18px);
  border-bottom: 1px solid rgba(56, 189, 248, 0.2);
  box-shadow: 0 10px 40px rgba(2, 6, 23, 0.6);
}

.header-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-md) var(--spacing-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-lg);
}

.logo {
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-decoration: none;
  color: var(--color-text);
  position: relative;
  padding-left: var(--spacing-md);
}

.logo::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 6px;
  height: 32px;
  border-radius: 999px;
  background: linear-gradient(180deg, var(--color-primary), var(--color-secondary));
  box-shadow: 0 0 20px rgba(56, 189, 248, 0.7);
}

nav ul {
  list-style: none;
  display: flex;
  gap: var(--spacing-lg);
}

nav a {
  text-decoration: none;
  font-size: 0.9rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-muted);
  transition: color 0.25s ease, text-shadow 0.25s ease;
}

nav a:hover,
nav a:focus-visible {
  color: var(--color-text);
  text-shadow: 0 0 12px rgba(56, 189, 248, 0.8);
}

.hero {
  padding: var(--spacing-xxl) 0 var(--spacing-xl);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::after {
  content: '';
  position: absolute;
  top: 10%;
  left: 50%;
  transform: translateX(-50%);
  width: 60vw;
  height: 60vw;
  max-width: 900px;
  background: radial-gradient(circle, rgba(56, 189, 248, 0.25), transparent 70%);
  filter: blur(20px);
  z-index: -1;
}

.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 6vw, 4rem);
  letter-spacing: -0.02em;
  margin-bottom: var(--spacing-sm);
}

.hero p {
  font-size: 1.1rem;
  color: var(--color-text-soft);
  margin-bottom: var(--spacing-xl);
}

.button-group {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-md);
  justify-content: center;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.95rem 2.4rem;
  border-radius: 999px;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-decoration: none;
  text-transform: uppercase;
  font-size: 0.85rem;
  border: 1px solid transparent;
  color: var(--color-text);
  position: relative;
  overflow: hidden;
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.button::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(120deg, rgba(255, 255, 255, 0.2), transparent 60%);
  opacity: 0;
  transition: opacity 0.2s ease;
}

.button:hover::after {
  opacity: 1;
}

.button:active {
  transform: translateY(2px) scale(0.98);
}

.button-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  box-shadow: 0 12px 30px rgba(14, 165, 233, 0.35);
}

.button-secondary {
  background: transparent;
  border-color: rgba(148, 163, 184, 0.4);
}

section {
  margin-bottom: var(--spacing-xxl);
}

.card,
.legal-section,
.contact-card,
.info-item,
.feature-card,
.contact-channel {
  background: var(--color-panel);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-card);
  backdrop-filter: blur(18px);
}

.card h2,
.legal-section h2,
.contact-card h2 {
  font-family: var(--font-display);
  font-size: 1.8rem;
  margin-bottom: var(--spacing-md);
  color: var(--color-text);
}

.card h3,
.legal-section h3,
.contact-card h3,
.info-item h3,
.contact-channel h3 {
  color: var(--color-primary);
  font-size: 1.1rem;
  margin: var(--spacing-lg) 0 var(--spacing-sm);
}

.card p,
.legal-section p,
.contact-card p,
.info-item p,
.contact-channel p {
  color: var(--color-text-soft);
  margin-bottom: var(--spacing-md);
}

.card ul,
.card ol,
.legal-section ul,
.legal-section ol {
  margin-left: 1.3rem;
  color: var(--color-text-soft);
}

.card li,
.legal-section li {
  margin-bottom: var(--spacing-xs);
}

.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: var(--spacing-lg);
}

.feature-card {
  position: relative;
  padding-top: var(--spacing-lg);
}

.feature-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  padding: 1px;
  background: linear-gradient(140deg, rgba(14, 165, 233, 0.4), rgba(192, 132, 252, 0.2));
  -webkit-mask:
    linear-gradient(#000, #000) content-box,
    linear-gradient(#000, #000);
  -webkit-mask-composite: xor;
          mask-composite: exclude;
}

.feature-icon {
  font-size: 2.5rem;
  margin-bottom: var(--spacing-md);
}

.download-section {
  text-align: center;
  background: var(--color-panel-strong);
  border: 1px solid var(--color-border-strong);
}

.download-badges p {
  color: var(--color-muted);
}

.highlight-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  font-size: 0.75rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-text);
  padding: 0.3rem 0.85rem;
  border-radius: 999px;
  border: 1px solid rgba(248, 250, 252, 0.2);
  background: rgba(248, 250, 252, 0.08);
}

.info-grid,
.contact-channels {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--spacing-lg);
}

.contact-channel a {
  color: var(--color-primary);
  text-decoration: none;
  word-break: break-all;
}

.contact-channel a:hover {
  color: var(--color-secondary);
}

.legal-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  margin-top: var(--spacing-md);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.legal-table th,
.legal-table td {
  padding: var(--spacing-md);
  text-align: left;
  color: var(--color-text-soft);
}

.legal-table th {
  width: 30%;
  background: rgba(56, 189, 248, 0.08);
  color: var(--color-text);
}

.legal-table tr:nth-child(even) td {
  background: rgba(248, 250, 252, 0.02);
}

.legal-notice,
.contact-meta {
  font-size: 0.85rem;
  color: var(--color-muted);
}

footer {
  padding: var(--spacing-xl) var(--spacing-lg) var(--spacing-xxl);
  background: rgba(2, 6, 23, 0.9);
  border-top: 1px solid rgba(56, 189, 248, 0.2);
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  text-align: center;
}

.footer-links {
  margin-bottom: var(--spacing-md);
}

.footer-links a {
  color: var(--color-muted);
  margin: 0 var(--spacing-sm);
  text-decoration: none;
  font-size: 0.85rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

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

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

.fade-in {
  opacity: 0;
  transform: translateY(20px);
}

@media (max-width: 900px) {
  nav ul {
    flex-wrap: wrap;
    justify-content: flex-end;
  }

  .header-content {
    flex-direction: column;
  }
}

@media (max-width: 640px) {
  .header-content {
    align-items: flex-start;
  }

  .button {
    width: 100%;
  }

  .card,
  .legal-section,
  .contact-card,
  .download-section {
    padding: var(--spacing-lg);
  }
}