:root {
      --bg: #fafafa;
      --text: #1a1a1a;
      --muted: #666;
      --accent: #3b82f6;
      --border: #e5e5e5;
      --code-bg: #f3f4f6;
    }
    @media (prefers-color-scheme: dark) {
      :root {
        --bg: #0f0f0f;
        --text: #f5f5f5;
        --muted: #999;
        --accent: #60a5fa;
        --border: #262626;
        --code-bg: #1a1a1a;
      }
    }
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: var(--bg);
      color: var(--text);
      line-height: 1.6;
      padding: 2rem 1rem;
      max-width: 720px;
      margin: 0 auto;
    }
    header {
      margin-bottom: 2.5rem;
      padding-bottom: 1.5rem;
      border-bottom: 1px solid var(--border);
    }
    h1 {
      font-size: 1.5rem;
      font-weight: 600;
      margin-bottom: 0.5rem;
    }
    .subtitle {
      color: var(--muted);
      font-size: 0.95rem;
    }
    .notice {
      background: var(--code-bg);
      border-left: 3px solid var(--accent);
      padding: 0.75rem 1rem;
      border-radius: 0 4px 4px 0;
      margin: 1.5rem 0;
      font-size: 0.9rem;
      color: var(--muted);
    }
    .notice.warning {
      border-left-color: #f59e0b;
    }
    section { margin: 2rem 0; }
    h2 {
      font-size: 1.2rem;
      font-weight: 600;
      margin-bottom: 1rem;
    }
    ul {
      list-style: none;
      padding-left: 0;
    }
    li {
      margin: 0.75rem 0;
      padding-left: 1.25rem;
      position: relative;
    }
    li::before {
      content: "•";
      color: var(--accent);
      position: absolute;
      left: 0;
      font-weight: bold;
    }
    .feature-title {
      font-weight: 600;
      display: block;
      margin-bottom: 0.25rem;
    }
    code {
      background: var(--code-bg);
      padding: 0.15rem 0.4rem;
      border-radius: 4px;
      font-family: ui-monospace, SFMono-Regular, monospace;
      font-size: 0.9em;
    }
    a {
      color: var(--accent);
      text-decoration: none;
    }
    a:hover { text-decoration: underline; }
    .links {
      display: flex;
      gap: 1rem;
      flex-wrap: wrap;
      margin-top: 1rem;
    }
    .btn {
      display: inline-block;
      padding: 0.5rem 1rem;
      background: var(--accent);
      color: white;
      border-radius: 6px;
      font-size: 0.9rem;
      font-weight: 500;
    }
    .btn:hover {
      opacity: 0.9;
      text-decoration: none;
    }
    .btn-outline {
      background: transparent;
      border: 1px solid var(--border);
      color: var(--text);
    }
    .btn-outline:hover {
      background: var(--code-bg);
    }
    footer {
      margin-top: 3rem;
      padding-top: 1.5rem;
      border-top: 1px solid var(--border);
      color: var(--muted);
      font-size: 0.9rem;
    }

    .converter-section {
  margin: 2.5rem 0;
  padding: 2rem;
  background: var(--code-bg);
  border-radius: 8px;
  border: 1px solid var(--border);
}

.converter-section h2 {
  margin-bottom: 1.5rem;
  text-align: center;
}

.converter-box {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.input-group {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.converter-input {
  flex: 1;
  min-width: 200px;
  padding: 0.75rem 1rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--bg);
  color: var(--text);
  font-family: ui-monospace, SFMono-Regular, monospace;
  font-size: 0.9rem;
  outline: none;
  transition: border-color 0.2s;
}

.converter-input:focus {
  border-color: var(--accent);
}

.converter-input.output {
  background: var(--bg);
  cursor: default;
}

.arrow {
  font-size: 1.5rem;
  color: var(--muted);
  font-weight: bold;
}

.convert-btn {
  align-self: flex-start;
  margin-top: 0.5rem;
}

@media (max-width: 640px) {
  .input-group {
    flex-direction: column;
    align-items: stretch;
  }
  
  .arrow {
    text-align: center;
    transform: rotate(90deg);
  }
}