html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  overflow-x: hidden;
  font-family: system-ui, sans-serif;
  background: #f2f4f7;
}

body {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: 100vh;
}

/* 📱 Üst Menü */
.menu {
  display: flex;
  justify-content: space-around;
  width: 100%;
  background: #007aff;
  position: sticky;
  top: 0;
  z-index: 10;
}

.menu button {
  flex: 1;
  background: none;
  border: none;
  color: white;
  font-size: 16px;
  padding: 14px 0;
  cursor: pointer;
  transition: background 0.2s;
}

.menu button.active {
  background: rgba(255,255,255,0.2);
  font-weight: 600;
}

.menu button:hover {
  background: rgba(255,255,255,0.3);
}

/* 🧾 İçerik kutusu */
.container {
  background: white;
  padding: 20px;
  border-radius: 12px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  width: 100%;
  max-width: 400px;
  margin: 20px;
  box-sizing: border-box;
}

h2 {
  text-align: center;
  margin-bottom: 20px;
  color: #333;
}

.form-group {
  margin-bottom: 15px;
}

label {
  font-weight: 600;
  color: #444;
  display: block;
  margin-bottom: 6px;
}

input, select {
  width: 100%;
  padding: 10px;
  font-size: 16px;
  border: 1px solid #ccc;
  border-radius: 8px;
  outline: none;
  box-sizing: border-box;
}

input:focus, select:focus {
  border-color: #007aff;
}

.user-row {
  display: flex;
  gap: 8px;
}

#addUserBtn {
  flex-shrink: 0;
  padding: 0 12px;
  font-size: 22px;
  border: none;
  background: #007aff;
  color: white;
  border-radius: 8px;
  cursor: pointer;
}

.save-btn {
  width: 100%;
  padding: 12px;
  background: #007aff;
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 16px;
  cursor: pointer;
}

.save-btn:hover {
  background: #005bb5;
}

/* 📋 Harcama listesi */
#expenseList {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.expense-item {
  background: #f8f9fb;
  border: 1px solid #ddd;
  border-radius: 8px;
  padding: 10px;
}

.expense-item strong {
  color: #007aff;
}

/* Popup */
.popup {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.4);
  justify-content: center;
  align-items: center;
  z-index: 10;
}

.popup-content {
  background: white;
  padding: 20px;
  border-radius: 10px;
  width: 90%;
  max-width: 320px;
}

.popup-buttons {
  display: flex;
  justify-content: space-between;
  gap: 10px;
}

.close-btn {
  flex: 1;
  background: #ccc;
  color: black;
  border: none;
  padding: 12px;
  border-radius: 8px;
  cursor: pointer;
}

@media (max-width: 480px) {
  .container {
    margin: 10px;
    padding: 15px;
  }
  input, select, button {
    font-size: 15px;
  }
}