* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Segoe UI", sans-serif;
}

body {
  background: #f4f6f9;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

.container {
  background: #fff;
  padding: 20px;
  width: 350px;
  border-radius: 12px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

h1 {
  text-align: center;
  margin-bottom: 20px;
  color: #333;
}

.balance {
  text-align: center;
  margin-bottom: 20px;
}

.balance h2 {
  font-size: 1.5rem;
  margin-bottom: 10px;
}

.summary {
  display: flex;
  justify-content: space-between;
}

.summary p {
  font-weight: bold;
}

form {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 20px;
}

input, button {
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 8px;
  outline: none;
}

button {
  background: #28a745;
  color: white;
  border: none;
  cursor: pointer;
  transition: 0.3s;
}

button:hover {
  background: #218838;
}

ul {
  list-style: none;
}

ul li {
  background: #f1f1f1;
  margin: 8px 0;
  padding: 10px;
  border-radius: 6px;
  display: flex;
  justify-content: space-between;
}

li.plus {
  border-right: 5px solid #28a745;
}

li.minus {
  border-right: 5px solid #dc3545;
}