:root {
  --primary: #0056b3;
  --primary-hover: #003d80;
  --danger: #d9534f;
  --danger-hover: #c9302c;
  --bg-color: #f4f6f8;
  --card-bg: #ffffff;
  --text-color: #333333;
  --text-muted: #6c757d;
  --border-color: #cccccc;
  --focus-ring: 0 0 0 3px rgba(0, 86, 179, 0.25);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.5;
  padding-bottom: 2rem;
}

.container {
  width: 100%;
  max-width: 600px;
  margin: 0 auto;
  padding: 0 1rem;
}

/* Alert box */
.alert {
  padding: 0.75rem 1rem;
  border-radius: 8px;
  margin-bottom: 1rem;
  font-size: 0.9rem;
}

.alert-danger {
  background-color: #f8d7da;
  color: #842029;
  border: 1px solid #f5c2c7;
}

/* Header */
.app-header {
  background-color: var(--primary);
  color: #ffffff;
  padding: 1.25rem 0;
  text-align: center;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  margin-bottom: 1.25rem;
}

.app-header h1 {
  font-size: 1.5rem;
  font-weight: 700;
}

.subtitle {
  font-size: 0.9rem;
  opacity: 0.9;
}

/* Cards */
.card {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 1.25rem;
  margin-bottom: 1.25rem;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  border: 1px solid var(--border-color);
}

.card h2 {
  font-size: 1.2rem;
  margin-bottom: 1rem;
  color: var(--primary);
}

/* Dashboard Summary */
.total-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: #eef5fc;
  padding: 1rem;
  border-radius: 8px;
  margin-bottom: 1rem;
}

.total-label {
  font-weight: 600;
  font-size: 1.1rem;
}

.total-amount {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--primary);
}

.category-summary h3 {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.category-totals-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.5rem;
}

.cat-item {
  background: #f8f9fa;
  padding: 0.5rem 0.75rem;
  border-radius: 6px;
  font-size: 0.85rem;
  display: flex;
  justify-content: space-between;
  border: 1px solid #e9ecef;
}

/* Forms & Inputs */
.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 0.35rem;
}

.required {
  color: var(--danger);
}

.form-control {
  width: 100%;
  min-height: 48px; /* Touch-friendly size */
  padding: 0.75rem;
  font-size: 1rem;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background-color: #ffffff;
  transition: border-color 0.15s ease-in-out;
}

.form-control:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: var(--focus-ring);
}

.error-msg {
  color: var(--danger);
  font-size: 0.8rem;
  display: block;
  margin-top: 0.25rem;
  min-height: 1.1rem;
}

/* Buttons */
.btn {
  display: inline-block;
  min-height: 48px; /* Touch-friendly button size */
  padding: 0.75rem 1.25rem;
  font-size: 1rem;
  font-weight: 600;
  text-align: center;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  touch-action: manipulation;
}

.btn-block {
  width: 100%;
}

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

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

.btn-delete {
  background-color: transparent;
  color: var(--danger);
  border: 1px solid var(--danger);
  min-height: 36px;
  padding: 0.35rem 0.75rem;
  font-size: 0.85rem;
  border-radius: 6px;
}

.btn-delete:active {
  background-color: var(--danger);
  color: #ffffff;
}

/* Filter Section */
.list-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

.count-badge {
  font-size: 0.85rem;
  background-color: #e9ecef;
  color: var(--text-muted);
  padding: 0.2rem 0.6rem;
  border-radius: 12px;
}

.filter-controls {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

/* Expense List */
.expense-list {
  list-style: none;
}

.expense-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.85rem 0;
  border-bottom: 1px solid #e9ecef;
}

.expense-item:last-child {
  border-bottom: none;
}

.expense-details {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.expense-title {
  font-weight: 600;
  font-size: 0.95rem;
}

.expense-meta {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.expense-right {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.expense-amount-tag {
  font-weight: 700;
  font-size: 1rem;
  color: var(--text-color);
}

.empty-state {
  text-align: center;
  color: var(--text-muted);
  padding: 1.5rem 0;
  font-style: italic;
}

.app-footer {
  text-align: center;
  margin-top: 1.5rem;
  color: var(--text-muted);
}

/* Media Queries for Desktop layout */
@media (min-width: 480px) {
  .filter-controls {
    flex-direction: row;
  }
}