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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
  color: #e4e4e7;
  min-height: 100vh;
  line-height: 1.6;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

header {
  text-align: center;
  margin-bottom: 2rem;
}

.back {
  display: inline-block;
  color: #818cf8;
  text-decoration: none;
  margin-bottom: 1rem;
  font-size: 0.9rem;
}

.back:hover {
  text-decoration: underline;
}

h1 {
  font-size: 2rem;
  margin-bottom: 0.5rem;
  color: #fff;
}

.subtitle {
  color: #a1a1aa;
  font-size: 1rem;
}

main {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.input-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.input-section {
  background: rgba(255, 255, 255, 0.05);
  border-radius: 12px;
  padding: 1rem;
  border: 1px solid rgba(255, 255, 255, 0.1);
}

label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
  color: #d4d4d8;
  font-size: 0.9rem;
}

textarea {
  width: 100%;
  padding: 0.875rem;
  font-size: 0.85rem;
  font-family: 'SF Mono', Monaco, 'Courier New', monospace;
  background: rgba(0, 0, 0, 0.3);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 8px;
  color: #fff;
  resize: vertical;
}

textarea:focus {
  outline: none;
  border-color: #818cf8;
  box-shadow: 0 0 0 3px rgba(129, 140, 248, 0.2);
}

.button-row {
  display: flex;
  gap: 0.75rem;
}

.primary-btn, .secondary-btn {
  padding: 0.875rem 1.5rem;
  font-size: 0.95rem;
  font-weight: 600;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s;
}

.primary-btn {
  flex: 1;
  background: linear-gradient(135deg, #6366f1 0%, #818cf8 100%);
  color: #fff;
}

.secondary-btn {
  background: rgba(255, 255, 255, 0.1);
  color: #d4d4d8;
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.primary-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

.secondary-btn:hover {
  background: rgba(255, 255, 255, 0.15);
  color: #fff;
}

.results {
  background: rgba(255, 255, 255, 0.05);
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  overflow: hidden;
}

.results.hidden {
  display: none;
}

.stats-bar {
  display: flex;
  gap: 1.5rem;
  padding: 0.875rem 1rem;
  background: rgba(0, 0, 0, 0.2);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  font-size: 0.85rem;
}

.stat {
  color: #a1a1aa;
}

.stat.added {
  color: #4ade80;
}

.stat.removed {
  color: #f87171;
}

.diff-output {
  padding: 1rem;
  font-family: 'SF Mono', Monaco, 'Courier New', monospace;
  font-size: 0.85rem;
  max-height: 400px;
  overflow-y: auto;
}

.diff-line {
  padding: 0.125rem 0.5rem;
  margin: 0 -0.5rem;
  white-space: pre-wrap;
  word-break: break-all;
}

.diff-line.added {
  background: rgba(34, 197, 94, 0.15);
  color: #4ade80;
}

.diff-line.removed {
  background: rgba(239, 68, 68, 0.15);
  color: #f87171;
}

.diff-line.unchanged {
  color: #71717a;
}

.line-number {
  display: inline-block;
  width: 3rem;
  color: #52525b;
  user-select: none;
}

footer {
  text-align: center;
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  color: #71717a;
  font-size: 0.875rem;
}

footer a {
  color: #818cf8;
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

@media (max-width: 700px) {
  .input-row {
    grid-template-columns: 1fr;
  }
  
  .button-row {
    flex-wrap: wrap;
  }
  
  .primary-btn {
    width: 100%;
  }
}