:root {
  --bg-primary: #0f1117;
  --bg-secondary: #1a1d27;
  --border-color: #2d3148;
  --text-primary: #e2e8f0;
  --text-secondary: #94a3b8;
  --accent-primary: #7c6af7;
  --accent-hover: #6a58e0;
  --text-muted: #475569;
}

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

body {
  font-family: system-ui, -apple-system, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
}

header {
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

header a.logo {
  color: var(--accent-primary);
  font-weight: 700;
  font-size: 20px;
  text-decoration: none;
  transition: color 0.2s ease;
}

header a.logo:hover,
header a.logo:focus-visible {
  color: var(--accent-hover);
}

nav a {
  color: var(--text-secondary);
  text-decoration: none;
  margin-left: 20px;
  font-size: 14px;
  transition: color 0.2s ease;
}

nav a:hover,
nav a:focus-visible {
  color: var(--text-primary);
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
  border-radius: 2px;
}

.container {
  max-width: 860px;
  margin: 48px auto;
  padding: 0 24px;
}

h1 {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 8px;
}

.subtitle {
  color: #94a3b8;
  font-size: 15px;
  margin-bottom: 32px;
}

.tool-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 24px;
  margin-bottom: 20px;
}

label {
  display: block;
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 6px;
  font-weight: 500;
}

input,
select {
  width: 100%;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 10px 14px;
  color: var(--text-primary);
  font-size: 15px;
  outline: none;
  transition: border-color 0.2s ease;
}

input:hover,
select:hover {
  border-color: var(--accent-primary);
}

input:focus,
select:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 2px rgba(124, 106, 247, 0.1);
}

input:focus-visible,
select:focus-visible {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

/* Improved accessibility for keyboard navigation */
button:focus-visible {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

.result-box {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 14px;
  font-family: monospace;
  font-size: 18px;
  color: var(--accent-primary);
  margin-top: 16px;
  word-break: break-all;
}

button.copy-btn {
  margin-top: 12px;
  background: var(--accent-primary);
  color: white;
  border: none;
  border-radius: 8px;
  padding: 10px 20px;
  font-size: 14px;
  cursor: pointer;
  font-weight: 600;
  transition: background-color 0.2s ease;
}

button.copy-btn:hover,
button.copy-btn:focus-visible {
  background: var(--accent-hover);
}

button.copy-btn:focus-visible {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

.description {
  margin-top: 40px;
  color: var(--text-secondary);
  line-height: 1.7;
  font-size: 15px;
}

.description h2 {
  color: var(--text-primary);
  font-size: 18px;
  margin: 24px 0 8px;
}

footer {
  text-align: center;
  padding: 32px;
  color: var(--text-muted);
  font-size: 13px;
  border-top: 1px solid var(--border-color);
  margin-top: 60px;
}

footer a:focus-visible {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
  border-radius: 2px;
}

@media (max-width: 768px) {
  .container {
    margin: 24px auto;
  }

  header {
    flex-direction: column;
    gap: 16px;
  }

  nav a {
    margin-left: 0;
    margin-right: 16px;
  }

  h1 {
    font-size: 24px;
  }
}

@media (max-width: 480px) {
  header {
    padding: 12px 16px;
  }

  header a.logo {
    font-size: 18px;
  }

  nav a {
    font-size: 13px;
    margin-right: 12px;
  }

  .container {
    margin: 20px auto;
    padding: 0 16px;
  }

  h1 {
    font-size: 20px;
  }

  .subtitle {
    font-size: 14px;
  }

  .tool-card {
    padding: 16px;
  }

  .input-grid {
    grid-template-columns: 1fr;
  }

  button.copy-btn {
    width: 100%;
  }
}