/* CSS Variables for Easy Customization & Duolingo-inspired Theme */
:root {
  --primary-color: #58cc02;
  --primary-hover: #61e002;
  --primary-dark: #58a700;
  --secondary-color: #1cb0f6;
  --secondary-dark: #1899d6;
  --danger-color: #ff4b4b;
  --danger-dark: #ea2b2b;
  --bg-color: #f7f9fa;
  --card-bg: #ffffff;
  --text-main: #3c3c3c;
  --text-muted: #777777;
  --border-color: #e5e5e5;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 18px;
  --font-family: 'Nunito', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.5;
  min-height: 100vh;
  padding: 24px 16px;
}

.container {
  max-width: 1080px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  min-height: calc(100vh - 48px);
}

/* Header */
.header {
  text-align: center;
  margin-bottom: 24px;
}

.header h1 {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--primary-color);
  letter-spacing: -0.5px;
}

/* Main Two-Column Layout using Flexbox */
.main-layout {
  display: flex;
  gap: 24px;
  align-items: flex-start;
  flex: 1;
}

/* Cards */
.card {
  background-color: var(--card-bg);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: 0 4px 0 var(--border-color);
}

/* Left Column: Form */
.form-column {
  flex: 1 1 320px;
}

.form-column h2 {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 18px;
  color: var(--text-main);
}

.form-group {
  display: flex;
  flex-direction: column;
  margin-bottom: 16px;
}

.form-group label {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-muted);
  margin-bottom: 6px;
}

input[type="text"],
input[type="number"],
select {
  font-family: var(--font-family);
  font-size: 1rem;
  font-weight: 600;
  padding: 10px 14px;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  outline: none;
  background-color: #ffffff;
  color: var(--text-main);
  transition: border-color 0.2s;
}

input[type="text"]:focus,
input[type="number"]:focus,
select:focus {
  border-color: var(--primary-color);
}

.form-group-buttons {
  display: flex;
  gap: 10px;
}

/* Buttons (Duolingo 3D button feel) */
.btn {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  font-family: var(--font-family);
  font-size: 0.95rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 10px 18px;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: transform 0.1s, box-shadow 0.1s;
}

.btn:active {
  transform: translateY(2px);
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.2) !important;
}

.btn-primary {
  width: 100%;
  background-color: var(--primary-color);
  color: #ffffff;
  box-shadow: 0 4px 0 var(--primary-dark);
}

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

.btn-update,
.btn-delete,
.btn-add-category,
.btn-submit-category,
.btn-cancel, 
.btn-update-cancel {
  color: #ffffff;
  padding: 6px 12px;
  font-size: 0.8rem;
}

.btn-update {
  background-color: var(--secondary-color);
  box-shadow: 0 3px 0 var(--secondary-dark);
}

.btn-delete,
.btn-cancel, 
.btn-update-cancel {
  background-color: var(--danger-color);
  box-shadow: 0 3px 0 var(--danger-dark);
}

.btn-add-category,
.btn-submit-category {
  background-color: var(--primary-color);
  box-shadow: 0 3px 0 var(--primary-dark);
}

/* Right Column: Toolbar & Table */
.list-column {
  flex: 2 1 500px;
}

.toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 20px;
  padding-bottom: 16px;
  border-bottom: 2px solid var(--border-color);
}

.filter-group {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 8px;
}

.filter-group label {
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--text-muted);
}

.filter-group select,
.add-category input {
  padding: 8px 12px;
  font-size: 0.9rem;
}

.add-category {
  flex: 1;
}

.add-category input {
  width: 40%;
}

.total-display {
  align-self: flex-start;
  display: flex;
  align-items: center;
  gap: 8px;
  background-color: #f0fdf0;
  border: 2px solid #d7ffb8;
  padding: 8px 14px;
  border-radius: var(--radius-md);
}

.total-display span {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-muted);
}

.total-display strong {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--primary-dark);
}

.hidden {
  display: none;
}

/* Table */
.table-wrapper {
  overflow-x: auto;
}

.expense-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

.expense-table th {
  padding: 12px 14px;
  font-size: 0.85rem;
  font-weight: 800;
  text-transform: uppercase;
  color: var(--text-muted);
  border-bottom: 2px solid var(--border-color);
}

.expense-table td,
.empty-message {
  padding: 14px;
  border-bottom: 1px solid var(--border-color);
  font-weight: 600;
  vertical-align: middle;
}

.empty-message {
  text-align: center;
}

.expense-table .amount {
  font-weight: 800;
  color: var(--text-main);
}

.expense-table .actions {
  display: flex;
  gap: 8px;
}

/* Category Badges */
.badge {
  display: inline-block;
  padding: 4px 10px;
  font-size: 0.75rem;
  font-weight: 800;
  border-radius: var(--radius-sm);
  background-color: #eef2f5;
  color: #4b4b4b;
}

.badge-food {
  background-color: #fff4e5;
  color: #ff9600;
}

.badge-transportation {
  background-color: #e5f6fd;
  color: #1cb0f6;
}

.badge-entertainment {
  background-color: #fde8f5;
  color: #ce82ff;
}

.badge-utilities {
  background-color: #e5fdee;
  color: #58cc02;
}

.badge-other {
  background-color: #f0f0f0;
  color: #777777;
}

/* Footer */
.footer {
  text-align: center;
  margin-top: 32px;
  padding: 16px 0;
}

.footer p {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-muted);
}

/* Responsive Flexbox Design */
@media (max-width: 768px) {
  .main-layout {
    flex-direction: column;
  }

  .form-column,
  .list-column {
    width: 100%;
  }

  .toolbar {
    flex-direction: column;
    align-items: stretch;
  }

  .total-display {
    justify-content: space-between;
  }

}