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

body {
  font-family: "Segoe UI", sans-serif;
  background-color: #ffffff;
  transition: background-color 0.3s, color 0.3s;
  margin-bottom: 20px;
}

body.dark-mode {
  background-color: rgba(6, 4, 5, 0.88);
}

.container {
  max-width: 600px;
  margin: auto;
  padding: 20px;
}

header {
  text-align: center;
  padding: 20px;
  background: #007bff;
  color: white;
  border-radius: 0 0 20px 20px;
}

.toggle-mode {
  float: right;
  cursor: pointer;
  margin-top: -40px;
  margin-right: 10px;
  font-size: 1.2rem;
}

.bmi-meaning {
  font-size: 20px;
  background: #f9fafb;
  padding: 20px;
  border-radius: 10px;
}

input,
select,
button {
  width: 100%;
  margin-top: 10px;
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 10px;
}

button:hover {
  background-color: #007bff;
  cursor: pointer;
}

.button-group {
  display: flex;
  gap: 10px;
  margin-top: 15px;
  cursor: pointer;
}

.button-group button {
  flex: 1;
}

#result {
  margin-top: 20px;
  font-weight: bold;
  color: #007bff;
  padding: 10px;
  border-radius: 10px;
  text-decoration: underline;
}

.tips,
.bmi-info {
  background: #f9fafb;
  padding: 15px;
  margin-top: 30px;
  border-left: 5px solid #007bff;
  border-radius: 10px;
}

.bmi-info div {
  margin-top: 20px;
}

h4 {
  margin-bottom: 10px;
  font-size: 20px;
}

@media (max-width: 600px) {
  .container {
    padding: 15px;
    max-width: 400px;
  }
}