:root {
  --primary-color: #2563eb;
  --primary-hover: #1d4ed8;
  --secondary-color: #64748b;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --error-color: #ef4444;
  --background: #f8fafc;
  --surface: #ffffff;
  --border: #e2e8f0;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  background: var(--background);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 2rem;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  text-align: center;
  margin-bottom: 3rem;
}

header h1 {
  font-size: 3rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  background: linear-gradient(135deg, var(--primary-color), var(--success-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

header p {
  color: var(--text-secondary);
  font-size: 1.1rem;
}

main {
  flex: 1;
  display: flex;
  flex-direction: column;
}

/* Upload Area */
.upload-area {
  background: var(--surface);
  border: 2px dashed var(--border);
  border-radius: 1rem;
  padding: 3rem 2rem;
  text-align: center;
  transition: all 0.3s ease;
  cursor: pointer;
  max-width: 600px;
  margin: 0 auto;
}

.upload-area:hover {
  border-color: var(--primary-color);
  background: #f8fafc;
}

.upload-area.dragover {
  border-color: var(--primary-color);
  background: #eff6ff;
  transform: scale(1.01);
}

.upload-content h2 {
  margin-bottom: 0.5rem;
  font-size: 1.5rem;
  font-weight: 600;
}

.upload-content p {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  font-size: 1rem;
}

.upload-icon {
  font-size: 3.5rem;
  margin-bottom: 1.5rem;
  opacity: 0.8;
}

/* File Info */
.file-info {
  background: var(--surface);
  border-radius: 1rem;
  padding: 2rem;
  box-shadow: var(--shadow);
  margin-bottom: 2rem;
}

.file-details {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2rem;
}

.file-icon {
  font-size: 3rem;
}

.file-meta h3 {
  font-size: 1.25rem;
  margin-bottom: 0.25rem;
}

.file-meta p {
  color: var(--text-secondary);
}

/* Transfer Link */
.transfer-link {
  background: var(--surface);
  border-radius: 1rem;
  padding: 2rem;
  box-shadow: var(--shadow);
}

.file-preview {
  background: #f8fafc;
  border-radius: 0.75rem;
  padding: 1.5rem;
  margin-bottom: 2rem;
  border: 1px solid var(--border);
}

.loading-state {
  text-align: center;
  padding: 2rem;
}

.loading-state .upload-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
  opacity: 0.8;
  animation: pulse 2s infinite;
}

.loading-state h3 {
  margin-bottom: 0.5rem;
  color: var(--primary-color);
}

.loading-state p {
  color: var(--text-secondary);
}

.transfer-link h3 {
  margin-bottom: 1rem;
  color: var(--success-color);
}

.link-container {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.link-container input {
  flex: 1;
  padding: 0.75rem;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  font-family: monospace;
  font-size: 0.9rem;
  background: #f8fafc;
}

.transfer-id {
  background: #f1f5f9;
  padding: 1rem;
  border-radius: 0.5rem;
  margin-bottom: 1rem;
  font-family: monospace;
}

.warning {
  color: var(--warning-color);
  font-weight: 500;
  margin-bottom: 2rem;
  text-align: center;
}

/* Status */
.status {
  margin-top: 2rem;
}

.status-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem;
  background: #f8fafc;
  border-radius: 0.5rem;
  margin-bottom: 0.5rem;
}

.status-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.status-dot.waiting {
  background: var(--warning-color);
  animation: pulse 2s infinite;
}

.status-dot.connected {
  background: var(--success-color);
}

.status-dot.transferring {
  background: var(--primary-color);
  animation: pulse 1s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

/* Buttons */
.btn {
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: 0.5rem;
  font-size: 1rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
  text-decoration: none;
  display: inline-block;
  text-align: center;
}

.btn-primary {
  background: var(--primary-color);
  color: white;
}

.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
}

.btn-secondary {
  background: var(--secondary-color);
  color: white;
}

.btn-secondary:hover {
  background: #475569;
  transform: translateY(-1px);
}

/* Modal */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
}

.modal-content {
  background: var(--surface);
  padding: 3rem;
  border-radius: 1rem;
  box-shadow: var(--shadow-lg);
  text-align: center;
  max-width: 400px;
  width: 90%;
}

.modal-content h2 {
  margin-bottom: 1rem;
  color: var(--success-color);
}

.modal-content p {
  margin-bottom: 2rem;
  color: var(--text-secondary);
}

/* Footer */
footer {
  text-align: center;
  padding: 2rem 0;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

/* Progress Bar */
.progress-bar {
  width: 100%;
  height: 8px;
  background: #e2e8f0;
  border-radius: 4px;
  overflow: hidden;
  margin: 1rem 0;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary-color), var(--success-color));
  border-radius: 4px;
  transition: width 0.3s ease;
  width: 0%;
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding: 1rem;
  }
  
  header h1 {
    font-size: 2rem;
  }
  
  .upload-area {
    padding: 2rem 1rem;
  }
  
  .link-container {
    flex-direction: column;
  }
  
  .file-details {
    flex-direction: column;
    text-align: center;
  }
}

/* File Input Styling */
.file-input-button {
  display: inline-block;
  margin: 1.5rem auto;
  padding: 0.875rem 1.75rem;
  font-size: 1rem;
  font-weight: 600;
  color: white;
  background: var(--primary-color);
  border: none;
  border-radius: 0.625rem;
  cursor: pointer;
  transition: all 0.2s ease;
  box-shadow: 0 2px 4px -1px rgba(37, 99, 235, 0.2);
  text-decoration: none;
  user-select: none;
  letter-spacing: 0.025em;
}

.file-input-button:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px -2px rgba(37, 99, 235, 0.25);
}

.file-input-button:active {
  transform: translateY(0);
  box-shadow: 0 2px 4px -1px rgba(37, 99, 235, 0.2);
}

.file-input-button:focus {
  outline: none;
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.3);
}

.file-input-hidden {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
  overflow: hidden;
}