:root {
  --primary-dark: #1a1a1a;
  --secondary-dark: #2a2a2a;
  --tertiary-dark: #3a3a3a;
  --accent-blue: #4a9eff;
  --accent-blue-hover: #357abd;
  --accent-green: #00d4aa;
  --accent-orange: #ff6b35;
  --accent-red: #ff4757;
  --text-primary: #ffffff;
  --text-secondary: #b0b0b0;
  --text-muted: #888888;
  --border-color: #404040;
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: linear-gradient(135deg, var(--primary-dark) 0%, var(--secondary-dark) 100%);
  color: var(--text-primary);
  min-height: 100vh;
  padding: 0;
  margin: 0;
}

.navbar {
  background: rgba(26, 26, 26, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0;
  margin-bottom: 2rem;
}

.navbar-brand {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary) !important;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.main-container {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 2rem;
}

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

.page-title {
  font-size: 2.5rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-green));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

.page-subtitle {
  color: var(--text-secondary);
  font-size: 1.1rem;
  font-weight: 400;
}

.section-card {
  background: rgba(42, 42, 42, 0.8);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 2rem;
  margin-bottom: 2rem;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  transition: all 0.3s ease;
}

.section-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4);
  border-color: var(--accent-blue);
}

.section-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.section-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-green));
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 0.9rem;
}

.btn-back {
  background: linear-gradient(135deg, var(--tertiary-dark), var(--secondary-dark));
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 500;
  font-size: 0.9rem;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  transition: all 0.3s ease;
  margin-bottom: 2rem;
}

.btn-back:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.3);
  border-color: var(--accent-blue);
  color: var(--text-primary);
  text-decoration: none;
}

.alert-danger {
  background: rgba(255, 71, 87, 0.1);
  border: 1px solid rgba(255, 71, 87, 0.3);
  color: var(--accent-red);
  border-radius: 8px;
  backdrop-filter: blur(5px);
  padding: 1rem;
  margin-bottom: 2rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.file-upload-container {
  border: 2px dashed var(--border-color);
  border-radius: 16px;
  padding: 3rem 2rem;
  text-align: center;
  background: rgba(58, 58, 58, 0.3);
  backdrop-filter: blur(5px);
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.file-upload-container::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-green));
  opacity: 0;
  transition: opacity 0.3s ease;
  z-index: 0;
}

.file-upload-container.dragover {
  border-color: var(--accent-blue);
  transform: scale(1.02);
  box-shadow: 0 12px 40px rgba(74, 158, 255, 0.3);
}

.file-upload-container.dragover::before {
  opacity: 0.1;
}

.file-upload-content {
  position: relative;
  z-index: 1;
}

.upload-icon {
  font-size: 4rem;
  color: var(--accent-blue);
  margin-bottom: 1rem;
  display: block;
}

.upload-label {
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-blue-hover));
  color: white;
  padding: 1rem 2rem;
  border-radius: 8px;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  transition: all 0.3s ease;
  border: none;
  box-shadow: 0 4px 12px rgba(74, 158, 255, 0.3);
  margin-bottom: 1rem;
}

.upload-label:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(74, 158, 255, 0.4);
  background: linear-gradient(135deg, var(--accent-blue-hover), var(--accent-blue));
}

.file-input {
  position: absolute;
  opacity: 0;
  width: 100%;
  height: 100%;
  cursor: pointer;
  z-index: 2;
}

.file-name {
  margin-top: 1rem;
  padding: 1rem;
  background: rgba(74, 158, 255, 0.1);
  border: 1px solid rgba(74, 158, 255, 0.3);
  border-radius: 8px;
  color: var(--text-primary);
  font-weight: 500;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  backdrop-filter: blur(5px);
}

.file-name.no-file {
  background: rgba(136, 136, 136, 0.1);
  border-color: rgba(136, 136, 136, 0.3);
  color: var(--text-muted);
}

.file-name i {
  font-size: 1.2rem;
  color: var(--accent-green);
}

.file-name.no-file i {
  color: var(--text-muted);
}

.upload-instructions {
  margin-top: 1rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.5;
}

.btn-upload {
  width: 100%;
  background: linear-gradient(135deg, var(--accent-green), #00b894);
  border: none;
  color: white;
  padding: 1rem 2rem;
  border-radius: 8px;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: all 0.3s ease;
  margin-top: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  box-shadow: 0 4px 12px rgba(0, 212, 170, 0.3);
}

.btn-upload:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 212, 170, 0.4);
  background: linear-gradient(135deg, #00b894, var(--accent-green));
}

.btn-upload:disabled {
  background: var(--tertiary-dark);
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* Responsive adjustments */
@media (max-width: 768px) {
  .main-container {
    padding: 0 1rem;
  }
  
  .section-card {
    padding: 1.5rem;
  }
  
  .page-title {
    font-size: 2rem;
  }
  
  .file-upload-container {
    padding: 2rem 1rem;
  }
  
  .upload-icon {
    font-size: 3rem;
  }
}