:root {
  --primary: #667eea;
  --secondary: #764ba2;
  --income: #1e8e3e;
  --expense: #c62828;
}

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

body {
  font-family: 'Segoe UI', Arial, sans-serif;
  background: linear-gradient(135deg, #f5f7fb, #e8f0ff);
  padding: 28px;
  min-height: 100vh;
  color: #1f2937;
}

.container { max-width: 960px; margin: auto; }

/* Header */
header {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  padding: 20px;
  border-radius: 12px;
  color: #fff;
  margin-bottom: 20px;
  box-shadow: 0 8px 24px rgba(0,0,0,.2);
}

/* Navigation */
nav {
  display: flex;
  gap: 20px;
  margin-bottom: 20px;
}
nav a {
  text-decoration: none;
  font-weight: bold;
  color: var(--primary);
}
nav a:hover { opacity: .7; }

/* Cards */
.dashboard { display: flex; gap: 12px; margin-bottom: 20px; }

.card {
  flex: 1;
  padding: 20px;
  border-radius: 12px;
  color: #fff;
  font-weight: 600;
  box-shadow: 0 8px 24px rgba(0,0,0,.1);
}

.balance { background: linear-gradient(135deg, #667eea, #764ba2); }
.income  { background: linear-gradient(135deg, #f093fb, #f5576c); }
.expenses { background: linear-gradient(135deg, #4facfe, #00f2fe); }

.card h3 { font-size: 13px; margin-bottom: 6px; }
.card p { font-size: 26px; font-weight: 800; }

/* Sections */
section {
  padding: 18px;
  border-radius: 12px;
  margin-bottom: 20px;
  background: rgba(255,255,255,.8);
  box-shadow: 0 8px 24px rgba(0,0,0,.08);
}

/* Forms */
form, .income-input-group, .dues-input-group {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

input, select {
  padding: 10px;
  border-radius: 8px;
  border: 1px solid #ddd;
  min-width: 150px;
}

input:focus, select:focus {
  outline: none;
  border-color: var(--primary);
}

/* Buttons */
button {
  padding: 10px 16px;
  border: none;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: #fff;
  cursor: pointer;
  font-weight: 600;
}
button:hover { opacity: .85; }

/* Lists */
ul { list-style: none; margin-top: 10px; }

li {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px;
  margin-bottom: 6px;
  border-radius: 8px;
  background: rgba(255,255,255,.6);
}

.tx-amount.income { color: var(--income); }
.tx-amount.expense { color: var(--expense); }

/* Error */
.error { color: var(--expense); font-weight: 600; margin-top: 8px; }

/* Responsive */
@media (max-width: 768px) {
  body { padding: 10px; }
  .dashboard { flex-direction: column; }
  nav { flex-direction: column; }
}