html {
  height: -webkit-fill-available;
}

.calc-container {
  max-width: 420px;
  margin: 0 auto;
  padding: 20px;
  background: #ffffff;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.calc-title {
  text-align: center;
  font-size: 20px;
  font-weight: bold;
  margin-bottom: 12px;
}

.calc-description {
  font-size: 13px;
  color: #666;
  margin-bottom: 15px;
}

.formula-box {
  background: #f5f5f5;
  padding: 10px;
  border-radius: 8px;
  font-size: 12px;
  margin-bottom: 15px;
}

.input-group {
  margin-bottom: 12px;
}
.input-group label {
  display: block;
  font-size: 13px;
  margin-bottom: 4px;
}
.input-group input {
  width: 100%;
  padding: 8px;
  border-radius: 6px;
  border: 1px solid #ddd;
  font-size: 14px;
}

.calc-btn {
  width: 100%;
  padding: 10px;
  background: #2c7be5;
  color: #fff;
  border: none;
  border-radius: 8px;
  font-weight: bold;
  cursor: pointer;
  margin-top: 8px;
}

.result-box {
  margin-top: 15px;
  background: #fafafa;
  padding: 12px;
  border-radius: 8px;
  font-size: 14px;
}