@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');

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

/* Dark theme (default) */
:root,
[data-theme="dark"] {
  --bg-primary: #0a0a0f;
  --bg-secondary: #12121a;
  --bg-card: rgba(255, 255, 255, 0.03);
  --bg-card-hover: rgba(255, 255, 255, 0.06);
  --border: rgba(255, 255, 255, 0.08);
  --border-hover: rgba(255, 255, 255, 0.15);
  --text-primary: #e8e8e8;
  --text-secondary: #8a8a9a;
  --text-muted: #5a5a6a;
  --accent: #7c6ff7;
  --accent-bright: #a78bfa;
  --accent-glow: rgba(124, 111, 247, 0.3);
  --cyan: #22d3ee;
  --cyan-glow: rgba(34, 211, 238, 0.2);
  --green: #34d399;
  --gradient: linear-gradient(135deg, #7c6ff7, #22d3ee);
  --grid-color: rgba(124, 111, 247, 0.03);
  --orb-color: rgba(124, 111, 247, 0.08);
}

/* Light theme */
[data-theme="light"] {
  --bg-primary: #f5f5f8;
  --bg-secondary: #ffffff;
  --bg-card: rgba(0, 0, 0, 0.02);
  --bg-card-hover: rgba(0, 0, 0, 0.05);
  --border: rgba(0, 0, 0, 0.08);
  --border-hover: rgba(0, 0, 0, 0.15);
  --text-primary: #1a1a2e;
  --text-secondary: #555570;
  --text-muted: #888898;
  --accent: #6c5ce7;
  --accent-bright: #7c6ff7;
  --accent-glow: rgba(108, 92, 231, 0.2);
  --cyan: #0891b2;
  --cyan-glow: rgba(8, 145, 178, 0.15);
  --green: #059669;
  --gradient: linear-gradient(135deg, #6c5ce7, #0891b2);
  --grid-color: rgba(108, 92, 231, 0.04);
  --orb-color: rgba(108, 92, 231, 0.06);
}

body {
  font-family: 'Space Grotesk', -apple-system, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
}

/* Animated grid background */
body::before {
  content: "";
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image:
    linear-gradient(var(--grid-color) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-color) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
  z-index: 0;
}

/* Gradient orbs */
body::after {
  content: "";
  position: fixed;
  top: -30%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, var(--orb-color), transparent 70%);
  pointer-events: none;
  z-index: 0;
}

/* Language bar */
.lang-bar {
  position: fixed;
  top: 16px;
  right: 20px;
  z-index: 100;
  display: flex;
  align-items: center;
  gap: 8px;
}

.theme-btn {
  width: 36px;
  height: 36px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-secondary);
  color: var(--text-secondary);
  font-size: 18px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
  backdrop-filter: blur(10px);
}

.theme-btn:hover {
  border-color: var(--accent);
  color: var(--accent-bright);
  box-shadow: 0 0 12px var(--accent-glow);
}

.lang-bar select {
  padding: 8px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-secondary);
  color: var(--text-primary);
  font-family: 'Space Grotesk', sans-serif;
  font-size: 13px;
  cursor: pointer;
  outline: none;
  backdrop-filter: blur(10px);
  transition: border-color 0.2s;
}

.lang-bar select:hover {
  border-color: var(--accent);
}

/* Pages */
.page {
  display: none;
  min-height: 100vh;
  min-height: 100dvh;
  padding: 50px 20px 24px;
  position: relative;
  z-index: 1;
}

.page.active {
  display: flex;
  flex-direction: column;
  justify-content: center;
  animation: fadeIn 0.4s ease;
}

#page2.active {
  justify-content: flex-start;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

.page-inner {
  max-width: 640px;
  margin: 0 auto;
}

/* Back button */
.btn-back {
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 20px;
  cursor: pointer;
  color: var(--text-secondary);
  margin-bottom: 28px;
  padding: 6px 14px;
  transition: all 0.2s;
}

.btn-back:hover {
  color: var(--accent-bright);
  border-color: var(--accent);
  box-shadow: 0 0 12px var(--accent-glow);
}

/* Logo */
.logo {
  text-align: center;
  font-size: 32px;
  font-weight: 700;
  letter-spacing: 6px;
  margin-bottom: 6px;
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.subtitle {
  text-align: center;
  color: var(--text-secondary);
  font-size: 13px;
  font-family: 'JetBrains Mono', monospace;
  margin-bottom: 20px;
  letter-spacing: 1px;
}

/* Features */
.features {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 20px;
}

.feature {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 18px;
  transition: all 0.3s;
}

.feature:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-hover);
}

.feature h3 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 4px;
  color: var(--text-primary);
}

.feature p {
  font-size: 12px;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Primary button */
.btn-primary {
  display: block;
  width: 200px;
  margin: 0 auto;
  padding: 12px 0;
  background: var(--gradient);
  color: #fff;
  border: none;
  border-radius: 10px;
  font-family: 'Space Grotesk', sans-serif;
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 2px;
  cursor: pointer;
  transition: all 0.3s;
  box-shadow: 0 4px 20px var(--accent-glow);
}

.btn-primary:hover {
  box-shadow: 0 6px 30px rgba(124, 111, 247, 0.5);
  transform: translateY(-1px);
}

/* Page 2 */
#page2 h2 {
  text-align: center;
  font-size: 24px;
  margin-bottom: 40px;
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.method {
  margin-bottom: 28px;
}

.method h3 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--text-primary);
}

.method a {
  color: var(--cyan);
  text-decoration: none;
  font-size: 14px;
  font-family: 'JetBrains Mono', monospace;
  margin-left: 16px;
  transition: all 0.2s;
}

.method a:hover {
  color: var(--accent-bright);
  text-shadow: 0 0 8px var(--cyan-glow);
}

/* Tip */
.tip {
  background: var(--bg-card);
  border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0;
  padding: 14px 18px;
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 28px;
  line-height: 1.7;
}

/* PC: wider layout */
@media (min-width: 768px) {
  .page {
    padding: 60px 40px 40px;
  }

  .page-inner {
    max-width: 720px;
  }

  .logo {
    font-size: 44px;
    letter-spacing: 8px;
  }

  .subtitle {
    font-size: 15px;
  }

  .feature h3 {
    font-size: 15px;
  }

  .feature p {
    font-size: 13px;
  }

  .btn-primary {
    width: 240px;
    font-size: 16px;
  }
}

/* Large screens */
@media (min-width: 1200px) {
  .page-inner {
    max-width: 800px;
  }

  .logo {
    font-size: 48px;
  }
}