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

body {
  font-family: "Poppins", sans-serif;
  line-height: 1.6;
  color: var(--foreground);
  background-color: var(--background);
  min-height: 100vh;
  font-weight: 400;
}

.main-container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 40px 20px;
}

.header-section {
  text-align: center;
  margin-bottom: 60px;
  color: var(--foreground);
  background-color: var(--background);
}

.header-section h1 {
  font-size: 3.5rem;
  font-weight: 700;
  margin-bottom: 20px;
  color: var(--foreground);
}

.header-section .subtitle {
  font-size: 1.25rem;
  color: var(--foreground);
  max-width: 800px;
  margin: 0 auto;
  line-height: 1.7;
}

.calculator-section {
  background-color: var(--background);
  border-radius: 24px;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
  padding: 50px;
  margin-bottom: 40px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(10px);
}

.content-section {
  background-color: var(--background);
  border-radius: 24px;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
  padding: 50px;
  margin-bottom: 40px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(10px);
}

.calculator-header {
  text-align: center;
  margin-bottom: 40px;
}

.calculator-header h2 {
  color: var(--foreground);
  font-size: 2.5rem;
  margin-bottom: 15px;
  font-weight: 600;
}

.calculator-header p {
  color: var(--foreground);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto;
}

.calculator-form {
  max-width: 500px;
  margin: 0 auto 40px auto;
}

.form-group {
  margin-bottom: 30px;
}

.form-group label {
  display: block;
  margin-bottom: 12px;
  font-weight: 600;
  color: var(--foreground);
  font-size: 1.1rem;
}

.form-group input {
  width: 100%;
  padding: 18px 24px;
  border: 2px solid #e2e8f0;
  border-radius: 16px;
  font-size: 1.1rem;
  transition: all 0.3s ease;
  background-color: var(--background);
  font-weight: 500;
  color: var(--foreground);
}

.form-group input:focus {
  outline: none;
  border-color: #3b82f6;
  background-color: var(--background);
  box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.1);
  transform: translateY(-2px);
}

.calculate-btn {
  background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
  color: white;
  border: none;
  padding: 18px 48px;
  border-radius: 16px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  text-transform: uppercase;
  letter-spacing: 1px;
  box-shadow: 0 10px 25px rgba(59, 130, 246, 0.3);
  width: 100%;
}

.calculate-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 15px 35px rgba(59, 130, 246, 0.4);
}

.calculate-btn:active {
  transform: translateY(-1px);
}

.maxpulse-error {
  background: linear-gradient(135deg, #fef2f2 0%, #fee2e2 100%);
  border: 2px solid #f87171;
  border-radius: 16px;
  padding: 20px;
  margin: 25px 0;
  color: #dc2626;
  font-weight: 600;
  display: none;
  text-align: center;
}

.maxpulse-error .error-icon {
  display: inline-block;
  margin-right: 10px;
  font-size: 1.3rem;
}

.maxpulse-result {
  background-color: var(--background);
  border-radius: 20px;
  padding: 40px;
  margin: 30px 0;
  color: var(--foreground);
  display: none;
  text-align: center;
  box-shadow: 0 20px 40px rgba(16, 185, 129, 0.3);
}

.result-maxpulse {
  font-size: 4rem;
  font-weight: 800;
  margin: 15px 0;
  text-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.result-label {
  font-size: 1.3rem;
  margin-bottom: 20px;
  opacity: 0.95;
  font-weight: 500;
}

.result-info {
  font-size: 1rem;
  opacity: 0.9;
  line-height: 1.6;
  margin-top: 20px;
  padding-top: 20px;
  border-top: 1px solid rgba(255, 255, 255, 0.3);
}

.training-zones {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  margin-top: 30px;
}

.zone-card {
  background-color: var(--background);
  padding: 20px;
  border-radius: 16px;
  text-align: center;
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.zone-card h4 {
  margin-bottom: 8px;
  font-size: 1rem;
  font-weight: 600;
  color: var(--foreground);
}

.zone-card .zone-range {
  font-size: 1.3rem;
  font-weight: 700;
}

h2 {
  color: var(--foreground);
  font-size: 2.25rem;
  margin-bottom: 25px;
  font-weight: 700;
  position: relative;
  padding-bottom: 15px;
}

h2::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 60px;
  height: 4px;
  background-color: var(--background);
  border-radius: 2px;
}

h3 {
  color: var(--foreground);
  font-size: 1.75rem;
  margin: 35px 0 20px 0;
  font-weight: 600;
}

h4 {
  color: var(--foreground);
  font-size: 1.3rem;
  margin: 25px 0 15px 0;
  font-weight: 600;
}

p {
  margin-bottom: 18px;
  line-height: 1.8;
  color: var(--foreground);
  font-size: 1.05rem;
}

.formula {
  background-color: var(--background);
  border-left: 5px solid #3b82f6;
  padding: 25px;
  margin: 25px 0;
  border-radius: 0 12px 12px 0;
  font-family: "Poppins", sans-serif;
  font-weight: 600;
  color: var(--foreground);
  font-size: 1.2rem;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

.highlight-box {
  background-color: var(--background);
  border: 2px solid #0ea5e9;
  border-radius: 16px;
  padding: 30px;
  margin: 30px 0;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

.warning-box {
  background-color: var(--background);
  border: 2px solid #f59e0b;
  border-radius: 16px;
  padding: 30px;
  margin: 30px 0;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

.heart-rate-table {
  width: 100%;
  border-collapse: collapse;
  margin: 30px 0;
  background-color: var(--background);
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
}

.heart-rate-table th {
  background-color: var(--background);
  color: var(--foreground);
  padding: 20px 15px;
  text-align: center;
  font-weight: 600;
  font-size: 1.05rem;
}

.heart-rate-table td {
  padding: 16px 15px;
  text-align: center;
  border-bottom: 1px solid #e2e8f0;
  font-weight: 500;
}

.heart-rate-table tbody tr:hover {
  background-color: var(--background);
  transform: scale(1.01);
  transition: all 0.2s ease;
}

.heart-rate-table tbody tr:nth-child(even) {
  background-color: var(--background);
}

.heart-rate-table th:first-child {
  background-color: var(--background);
}

.training-steps {
  background-color: var(--background);
  border-radius: 16px;
  padding: 30px;
  margin: 30px 0;
  border: 1px solid #bbf7d0;
}

.training-steps ol {
  margin-left: 25px;
}

.training-steps li {
  margin-bottom: 15px;
  line-height: 1.7;
  font-weight: 500;
}

.pulse-animation {
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0% {
    transform: scale(1);
  }

  50% {
    transform: scale(1.05);
  }

  100% {
    transform: scale(1);
  }
}

.professional-badge {
  display: inline-flex;
  align-items: center;
  background: linear-gradient(135deg, #10b981 0%, #059669 100%);
  color: #f8fafc;
  padding: 8px 16px;
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 20px;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 20px;
  margin: 30px 0;
}

.stat-card {
  background-color: var(--background);
  padding: 25px;
  border-radius: 16px;
  text-align: center;
  border: 1px solid #e2e8f0;
}

.stat-number {
  font-size: 2.5rem;
  font-weight: 800;
  color: #3b82f6;
  margin-bottom: 5px;
}

.stat-label {
  color: var(--foreground);
  font-weight: 500;
}

@media (max-width: 768px) {
  .main-container {
    padding: 20px 15px;
  }

  .calculator-section,
  .content-section {
    padding: 30px 25px;
  }

  .header-section h1 {
    font-size: 2.5rem;
  }

  .result-maxpulse {
    font-size: 3rem;
  }

  .heart-rate-table {
    font-size: 0.9rem;
  }

  .heart-rate-table th,
  .heart-rate-table td {
    padding: 12px 8px;
  }

  .training-zones {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .header-section h1 {
  font-size: 1.7rem;
  font-weight: 700;
  margin-bottom: 20px;
  color: var(--foreground);
}

.header-section .subtitle {
  font-size: 1rem;
}

  .calculator-section,
  .content-section {
    padding: 25px 20px;
  }
}