:root {
  --color-background-primary: #ffffff;
  --color-background-secondary: #f5f5f5;
  --color-background-tertiary: #efefef;
  --color-background-info: #378ADD;
  --color-background-danger: #f5e6e6;
  --color-background-success: #e6f5e6;

  --color-text-primary: #1a1a1a;
  --color-text-secondary: #666666;
  --color-text-tertiary: #999999;
  --color-text-info: #ffffff;
  --color-text-danger: #d32f2f;
  --color-text-success: #2e7d32;

  --color-border-tertiary: rgba(0, 0, 0, 0.1);
  --color-border-secondary: rgba(0, 0, 0, 0.2);
  --color-border-primary: rgba(0, 0, 0, 0.4);

  --border-radius-md: 8px;
  --border-radius-lg: 12px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-background-primary: #1a1a1a;
    --color-background-secondary: #2d2d2d;
    --color-background-tertiary: #3d3d3d;
    --color-background-info: #378ADD;
    --color-background-danger: #3d2626;
    --color-background-success: #263d26;

    --color-text-primary: #f0f0f0;
    --color-text-secondary: #b0b0b0;
    --color-text-tertiary: #808080;
    --color-text-info: #ffffff;
    --color-text-danger: #ff6b6b;
    --color-text-success: #66bb6a;

    --color-border-tertiary: rgba(255, 255, 255, 0.1);
    --color-border-secondary: rgba(255, 255, 255, 0.2);
    --color-border-primary: rgba(255, 255, 255, 0.4);
  }
}

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

html, body {
  width: 100%;
  height: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--color-background-primary);
  color: var(--color-text-primary);
  padding: 1rem;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
  -webkit-font-smoothing: antialiased;
}

.app {
  max-width: 500px;
  margin: 0 auto;
}

.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  padding: 1rem 0;
  border-bottom: 0.5px solid var(--color-border-tertiary);
}

.header h1 {
  font-size: 28px;
  font-weight: 500;
}

.currency-badge {
  background: var(--color-background-info);
  color: var(--color-text-info);
  padding: 6px 14px;
  border-radius: var(--border-radius-md);
  font-size: 12px;
  font-weight: 600;
}

.tabs {
  display: flex;
  gap: 0;
  margin-bottom: 1.5rem;
  border-bottom: 0.5px solid var(--color-border-tertiary);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.tab {
  padding: 12px 16px;
  border: none;
  background: none;
  cursor: pointer;
  color: var(--color-text-secondary);
  font-size: 14px;
  font-weight: 500;
  border-bottom: 2px solid transparent;
  white-space: nowrap;
  transition: color 0.2s;
}

.tab:active {
  opacity: 0.7;
}

.tab.active {
  color: var(--color-text-primary);
  border-bottom-color: var(--color-background-info);
}

.section {
  display: none;
  animation: fadeIn 0.2s;
}

.section.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

.metric-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 1.5rem;
}

.metric-card {
  background: var(--color-background-secondary);
  padding: 1rem;
  border-radius: var(--border-radius-md);
  text-align: center;
  border: 0.5px solid var(--color-border-tertiary);
}

.metric-label {
  font-size: 12px;
  color: var(--color-text-secondary);
  margin-bottom: 8px;
  font-weight: 500;
}

.metric-value {
  font-size: 20px;
  font-weight: 600;
  color: var(--color-text-primary);
}

.transaction-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.transaction-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px;
  background: var(--color-background-secondary);
  border-radius: var(--border-radius-md);
  border: 0.5px solid var(--color-border-tertiary);
  transition: background 0.2s;
}

.transaction-item:active {
  background: var(--color-background-tertiary);
}

.transaction-info {
  flex: 1;
}

.transaction-category {
  font-size: 13px;
  color: var(--color-text-secondary);
  margin-top: 2px;
}

.transaction-amount {
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text-danger);
}

.transaction-amount.income {
  color: var(--color-text-success);
}

.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  font-size: 13px;
  color: var(--color-text-secondary);
  margin-bottom: 6px;
  font-weight: 500;
}

.form-group input,
.form-group select {
  width: 100%;
  padding: 12px;
  border: 0.5px solid var(--color-border-tertiary);
  border-radius: var(--border-radius-md);
  font-size: 16px;
  background: var(--color-background-primary);
  color: var(--color-text-primary);
  -webkit-appearance: none;
  appearance: none;
}

.form-group input:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--color-background-info);
  box-shadow: 0 0 0 2px rgba(55, 138, 221, 0.1);
}

.form-group select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath fill='%23666666' d='M1 1l5 5 5-5'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
}

@media (prefers-color-scheme: dark) {
  .form-group select {
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath fill='%23b0b0b0' d='M1 1l5 5 5-5'/%3E%3C/svg%3E");
  }
}

button {
  padding: 12px 16px;
  border: 0.5px solid var(--color-border-secondary);
  background: var(--color-background-secondary);
  border-radius: var(--border-radius-md);
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text-primary);
  transition: background 0.2s;
  -webkit-appearance: none;
  appearance: none;
}

button:active {
  transform: scale(0.98);
  background: var(--color-background-tertiary);
}

button[onclick*="addTransaction"] {
  background: var(--color-background-info);
  color: var(--color-text-info);
  border-color: var(--color-background-info);
}

button[onclick*="exportToExcel"] {
  background: var(--color-background-success);
  color: var(--color-text-success);
  border-color: var(--color-background-success);
}

.budget-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px;
  background: var(--color-background-secondary);
  border-radius: var(--border-radius-md);
  margin-bottom: 8px;
  border: 0.5px solid var(--color-border-tertiary);
}

.budget-name {
  flex: 1;
}

.budget-name > div:first-child {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text-primary);
}

.budget-assigned {
  font-size: 12px;
  color: var(--color-text-secondary);
  margin-top: 4px;
}

.budget-progress {
  width: 80px;
  height: 6px;
  background: var(--color-border-tertiary);
  border-radius: 3px;
  margin: 0 12px;
  overflow: hidden;
  flex-shrink: 0;
}

.budget-progress-bar {
  height: 100%;
  background: var(--color-background-info);
  border-radius: 3px;
}

.budget-spent {
  font-size: 14px;
  font-weight: 600;
  min-width: 60px;
  text-align: right;
  color: var(--color-text-primary);
}

.budget-remaining {
  font-size: 12px;
  color: var(--color-text-secondary);
  text-align: right;
  margin-top: 2px;
}

h3 {
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text-primary);
}

@media (max-width: 400px) {
  body {
    padding: 0.75rem;
  }

  .header {
    margin-bottom: 1.5rem;
  }

  .metric-cards {
    grid-template-columns: 1fr;
  }

  .tab {
    padding: 10px 12px;
    font-size: 12px;
  }

  button {
    padding: 10px 12px;
    font-size: 13px;
  }
}