:root {
  --primary-color: #4F46E5;
  --primary-light: #6366F1;
  --secondary-color: #10B981;
  --accent-color: #F59E0B;
  --text-color: #1F2937;
  --light-gray: #F3F4F6;
  --medium-gray: #E5E7EB;
  --dark-gray: #6B7280;
  --white: #FFFFFF;
  --danger-color: #EF4444;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

body {
  background-color: #F9FAFB;
  color: var(--text-color);
  line-height: 1.6;
  padding: 20px;
}

.app-container {
  max-width: 1200px;
  margin: 0 auto;
  background-color: var(--white);
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 30px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--medium-gray);
  flex-wrap: wrap;
  gap: 20px;
}

.header-controls {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}

h1 {
  color: var(--primary-color);
  flex: 1;
  min-width: 250px;
  font-size: 28px;
  font-weight: 700;
}

h2 {
  margin-bottom: 15px;
  color: var(--primary-color);
  font-size: 1.3rem;
  font-weight: 600;
}

.form-section {
  margin-bottom: 30px;
  background-color: var(--white);
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.form-group {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 15px;
  margin-bottom: 15px;
}

.form-group.row {
  display: flex;
  flex-wrap: wrap;
  gap: 15px;
}

.form-group.row > div {
  flex: 1;
  min-width: 150px;
}

label {
  display: block;
  margin-bottom: 5px;
  font-weight: 500;
  color: var(--dark-gray);
  font-size: 14px;
}

input, textarea, select {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--medium-gray);
  border-radius: 6px;
  font-size: 15px;
  transition: all 0.2s ease;
  background-color: var(--white);
}

input:focus, textarea:focus, select:focus {
  outline: none;
  border-color: var(--primary-light);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

textarea {
  min-height: 100px;
  resize: vertical;
}

.logo-upload {
  margin-bottom: 20px;
}

.logo-preview {
  width: 180px;
  height: 120px;
  margin-top: 10px;
  border: 1px dashed var(--medium-gray);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  border-radius: 6px;
  background-color: var(--light-gray);
}

.logo-preview img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
}

#items-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  margin-bottom: 15px;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

#items-table th, #items-table td {
  padding: 12px 15px;
  text-align: left;
  border-bottom: 1px solid var(--medium-gray);
}

#items-table th {
  background-color: var(--primary-color);
  color: var(--white);
  font-weight: 600;
  text-transform: uppercase;
  font-size: 13px;
  letter-spacing: 0.5px;
}

#items-table tr:last-child td {
  border-bottom: none;
}

#items-table tr:hover td {
  background-color: rgba(79, 70, 229, 0.03);
}

#items-table input, #items-table select {
  padding: 8px 10px;
  font-size: 14px;
  border: 1px solid var(--medium-gray);
  background-color: var(--white);
}

.totals-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  max-width: 500px;
  margin-left: auto;
  background-color: var(--light-gray);
  padding: 20px;
  border-radius: 8px;
}

.subtotal, .total {
  display: flex;
  justify-content: space-between;
  font-size: 1.1rem;
  padding: 8px 0;
}

.total {
  font-size: 1.3rem;
  font-weight: bold;
  padding-top: 12px;
  border-top: 2px solid var(--medium-gray);
  color: var(--primary-color);
}

.tax-row, .discount-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 15px;
  padding: 8px 0;
}

.tax-row > div, .discount-row > div {
  flex: 1;
  min-width: 120px;
}

.discount-row {
  padding-bottom: 12px;
  border-bottom: 1px solid var(--medium-gray);
}

.action-buttons {
  display: flex;
  justify-content: flex-end;
  gap: 15px;
  margin-top: 30px;
}

.btn {
  padding: 12px 24px;
  border: none;
  border-radius: 6px;
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

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

.btn.primary:hover {
  background-color: var(--primary-light);
  transform: translateY(-2px);
  box-shadow: 0 4px 6px -1px rgba(79, 70, 229, 0.2), 0 2px 4px -1px rgba(79, 70, 229, 0.1);
}

.btn.secondary {
  background-color: var(--white);
  color: var(--text-color);
  border: 1px solid var(--medium-gray);
}

.btn.secondary:hover {
  background-color: var(--light-gray);
  transform: translateY(-2px);
}

.remove-item {
  background-color: var(--danger-color);
  color: white;
  border-radius: 4px;
  padding: 4px 8px;
  font-size: 12px;
  border: none;
  cursor: pointer;
}

.remove-item:hover {
  background-color: #DC2626;
}

.theme-selector, .currency-selector {
  display: flex;
  align-items: center;
  gap: 10px;
}

.currency-selector select {
  padding: 8px 12px;
  border-radius: 6px;
  border: 1px solid var(--medium-gray);
  background-color: var(--white);
}

@media (max-width: 768px) {
  .app-container {
    padding: 15px;
  }
  
  .form-group {
    grid-template-columns: 1fr;
  }
  
  .action-buttons {
    flex-direction: column;
  }
  
  .btn {
    width: 100%;
  }
  
  .header-controls {
    flex-direction: column;
    gap: 10px;
  }
  
  .theme-selector, .currency-selector {
    width: 100%;
  }
  
  .totals-grid {
    max-width: 100%;
  }
}

.payment-instructions {
  margin-top: 15px;
}

.payment-instructions label {
  font-weight: 500;
  color: var(--dark-gray);
  margin-bottom: 5px;
  display: block;
}

.payment-instructions input {
  width: 100%;
  padding: 10px 12px;
  margin-bottom: 10px;
  border: 1px solid var(--medium-gray);
  border-radius: 6px;
}