:root {
  --bg-primary: #f9fafb;
  --text-primary: #1e293b;
  --card-bg: #ffffff;
  --income-color: #10b981;
  --expense-color: #ef4444;
  --border-color: #e2e8f0;
  --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

[data-theme="dark"] {
  --bg-primary: #0f172a;
  --text-primary: #f1f5f9;
  --card-bg: #1e293b;
  --border-color: #334155;
  --shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

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

body {
  background: var(--bg-primary);
  min-height: 100vh;
  font-family: "Poppins", sans-serif;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  transition: background 0.3s ease, color 0.3s ease;
}

.container {
  width: 100%;
  max-width: 1200px;
  background-color: var(--card-bg);
  padding: 2rem;
  border-radius: 24px;
  box-shadow: var(--shadow);
  transition: background 0.3s ease;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 30px;
}

header h1 {
  font-size: 2.2rem;
  font-weight: 600;
  color: var(--text-primary);
}

.theme-btn {
  background: none;
  border: 2px solid var(--border-color);
  width: 42px;
  height: 42px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-primary);
  transition: all 0.3s ease;
}

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

.balance-container {
  text-align: center;
  margin-bottom: 30px;
  padding: 24px;
  border-radius: 1rem;
  box-shadow: var(--shadow);
  transition: background 0.3s ease;
  background: linear-gradient(135deg, #d1fae5, #a7f3d0);
}

[data-theme="dark"] .balance-container.positive {
  background: linear-gradient(135deg, #065f46, #0d9488);
}

.balance-container.negative {
  background: linear-gradient(135deg, #fee2e2, #fecaca);
}

[data-theme="dark"] .balance-container.negative {
  background: linear-gradient(135deg, #7f1d1d, #b91c1c);
}

.balance-container h1 {
  font-size: 2.8rem;
  margin: 15px 0;
  font-weight: 700;
}

.summary-cards {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-top: 24px;
}

.card {
  display: flex;
  align-items: center;
  gap: 12px;
  background: var(--card-bg);
  padding: 16px;
  border-radius: 12px;
  box-shadow: var(--shadow);
  min-width: 160px;
}

.card i {
  font-size: 1.4rem;
}

.income-card i {
  color: var(--income-color);
}

.expense-card i {
  color: var(--expense-color);
}

.card h3 {
  font-size: 1rem;
  color: var(--text-primary);
  opacity: 0.8;
}

.card p {
  font-size: 1.4rem;
  font-weight: 600;
  margin-top: 4px;
}

.income-card p {
  color: var(--income-color);
}

.expense-card p {
  color: var(--expense-color);
}

.charts-section {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-bottom: 30px;
}

.chart-wrapper {
  background: var(--card-bg);
  padding: 20px;
  border-radius: 16px;
  box-shadow: var(--shadow);
}

.main-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.transaction-container h2,
.form-container h2 {
  margin-bottom: 16px;
  color: var(--text-primary);
}

#transaction-list {
  list-style: none;
  max-height: 400px;
  overflow-y: auto;
  padding-right: 8px;
}

.transaction {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px;
  margin-bottom: 12px;
  border-radius: 12px;
  background: var(--card-bg);
  box-shadow: var(--shadow);
  border-right: 4px solid;
  animation: slideIn 0.3s ease;
}

.transaction.income {
  border-right-color: var(--income-color);
}

.transaction.expense {
  border-right-color: var(--expense-color);
}

.transaction .delete-btn {
  background: none;
  border: none;
  color: var(--expense-color);
  cursor: pointer;
  font-size: 1.2rem;
  opacity: 0;
  transition: opacity 0.2s;
  margin-left: 12px;
}

.transaction:hover .delete-btn {
  opacity: 1;
}

.form-group {
  margin-bottom: 20px;
}

label {
  display: block;
  margin-bottom: 8px;
  color: var(--text-primary);
  font-weight: 500;
}

input,
select {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background: var(--card-bg);
  color: var(--text-primary);
  font-size: 1rem;
}

button[type="submit"] {
  width: 100%;
  padding: 14px;
  background: linear-gradient(135deg, #0d9488, #10b981);
  color: white;
  border: none;
  border-radius: 8px;
  font-weight: 500;
  cursor: pointer;
  transition: transform 0.2s;
}

button[type="submit"]:hover {
  transform: translateY(-2px);
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateX(-20px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

#transaction-list::-webkit-scrollbar {
  width: 8px;
}
#transaction-list::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 4px;
}

@media (max-width: 900px) {
  .main-content,
  .charts-section {
    grid-template-columns: 1fr;
  }
  .container {
    padding: 1.5rem;
  }
}

@media (max-width: 480px) {
  .summary-cards {
    flex-direction: column;
    align-items: center;
  }
  header h1 {
    font-size: 1.8rem;
  }
}