:root {
  --primary-color: #2196F3;
  --hover-color: #1976D2;
  --bg-color: #f5f5f5;
  --text-color: #333;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.container {
  width: 100%;
  max-width: 600px;
  padding: 2rem;
  margin-top: 200px;
}

.upload-section {
  background: white;
  padding: 2rem;
  border-radius: 10px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  text-align: center;
}

h1 {
  margin-bottom: 1rem;
  color: var(--text-color);
}

p {
  margin-bottom: 2rem;
  color: #666;
}

.drop-zone {
  border: 2px dashed #ccc;
  border-radius: 8px;
  padding: 2rem;
  margin-bottom: 2rem;
  transition: border-color 0.3s ease;
  cursor: pointer;
}

.drop-zone.drag-over {
  border-color: var(--primary-color);
  background-color: rgba(33, 150, 243, 0.1);
}

.upload-icon {
  width: 64px;
  height: 64px;
  fill: #ccc;
  margin-bottom: 1rem;
}

.file-input-label {
  display: inline-block;
  color: var(--primary-color);
  cursor: pointer;
  font-weight: 500;
}

.file-input-label:hover {
  text-decoration: underline;
}

input[type="file"] {
  display: none;
}

.convert-btn {
  background-color: var(--primary-color);
  color: white;
  border: none;
  padding: 0.8rem 2rem;
  border-radius: 5px;
  cursor: pointer;
  font-size: 1rem;
  transition: background-color 0.3s ease;
}

.convert-btn:hover {
  background-color: var(--hover-color);
}

.convert-btn:disabled {
  background-color: #ccc;
  cursor: not-allowed;
}

.button-container {
  margin-top: 1.5rem;
}

.top-button {
  margin-bottom: 1rem;
  text-align: right;
}

.control-panel-btn {
  display: inline-block;
  background-color: var(--primary-color);
  color: white;
  text-decoration: none;
  padding: 0.8rem 2rem;
  border-radius: 5px;
  font-size: 1rem;
  transition: background-color 0.3s ease;
}

.control-panel-btn:hover {
  background-color: var(--hover-color);
}

.convert-btn + .button-container {
  margin-top: 1rem;
}

@keyframes bounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

.drop-zone.drag-over .upload-icon {
  animation: bounce 1s infinite;
}