.calc-container {
  max-width: 450px;
  margin: 20px auto;
  background: #ffffff;
  padding: 30px;
  border-radius: 20px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  font-family: 'Segoe UI', Arial, sans-serif;
  border: 1px solid #f0f0f0;
}

.calc-header {
  text-align: center;
  margin-bottom: 25px;
}

.calc-header h2 {
  color: #1a3c34;
  margin: 0;
  font-size: 26px;
}

.tabs {
  display: flex;
  margin-bottom: 25px;
  background: #f8f9fa;
  border-radius: 12px;
  padding: 6px;
}

.tab-btn {
  flex: 1;
  padding: 12px;
  border: none;
  background: none;
  cursor: pointer;
  font-weight: 700;
  color: #95a5a6;
  border-radius: 10px;
  transition: 0.3s;
}

.tab-btn.active {
  background: #ffffff;
  color: #2ecc71;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.05);
}

.input-group {
  margin-bottom: 20px;
}

.input-group label {
  display: block;
  margin-bottom: 8px;
  font-size: 15px;
  color: #2c3e50;
  font-weight: 600;
}

.input-group input {
  width: 100%;
  padding: 14px;
  border: 2px solid #edf2f7;
  border-radius: 10px;
  box-sizing: border-box;
  font-size: 16px;
}

.calc-btn {
  width: 100%;
  background: #2ecc71;
  color: white;
  padding: 16px;
  border: none;
  border-radius: 12px;
  font-size: 17px;
  font-weight: bold;
  cursor: pointer;
}

.result-box {
  margin-top: 25px;
  padding: 20px;
  background: #f0fff4;
  border-radius: 15px;
  border: 2px solid #c6f6d5;
  display: none;
  text-align: center;
}

.result-val {
  font-size: 22px;
  color: #22543d;
  font-weight: 800;
  display: block;
}