:root {
  font-family: Inter, system-ui, Avenir, Helvetica, Arial, sans-serif;
  line-height: 1.5;
  font-weight: 400;
  color: #213547;
  background-color: #f3f4f6;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  padding: 20px;
  min-width: 320px;
  min-height: 100vh;
}

h1 {
  font-size: 2.5em;
  line-height: 1.1;
  color: #1f2937;
  margin-bottom: 0.5rem;
}

h2 {
  font-size: 1.5em;
  color: #374151;
  margin-top: 2rem;
  margin-bottom: 1rem;
}

p {
  color: #6b7280;
  font-size: 1.1em;
}

.upload-section,
.detect-section,
.replace-section {
  background: white;
  border-radius: 12px;
  padding: 24px;
  margin: 20px 0;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

input[type="file"] {
  padding: 12px;
  border: 2px dashed #d1d5db;
  border-radius: 8px;
  width: 100%;
  max-width: 400px;
  margin: 10px 0;
  cursor: pointer;
}

input[type="file"]:hover {
  border-color: #3b82f6;
  background: #eff6ff;
}

button {
  background: #3b82f6;
  color: white;
  border: none;
  padding: 12px 24px;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 500;
  cursor: pointer;
  margin: 10px 5px;
  transition: all 0.2s;
}

button:hover {
  background: #2563eb;
  transform: translateY(-1px);
  box-shadow: 0 4px 6px rgba(37, 99, 235, 0.3);
}

button:active {
  transform: translateY(0);
}

#results {
  margin-top: 20px;
  padding: 20px;
  background: #f9fafb;
  border-radius: 8px;
  min-height: 100px;
}

#status {
  margin-top: 20px;
}