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

:root {
  --primary-600: #4f46e5;
  --primary-700: #4338ca;
  --primary-800: #3730a3;
  --primary-50: #eef2ff;
  --primary-100: #e0e7ff;
  --secondary-500: #8b5cf6;
  --secondary-600: #7c3aed;
  --accent-500: #06b6d4;
  --accent-600: #0891b2;
  --success-500: #10b981;
  --warning-500: #f59e0b;
  --error-500: #ef4444;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;
  --white: #ffffff;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1),
    0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1),
    0 8px 10px -6px rgb(0 0 0 / 0.1);
  --shadow-2xl: 0 25px 50px -12px rgb(0 0 0 / 0.25);
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
}

/* Add Google Fonts for better typography */
@import url("https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&display=swap");

body {
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto",
    "Oxygen", "Ubuntu", "Cantarell", sans-serif;
  background: linear-gradient(
    135deg,
    var(--primary-600) 0%,
    var(--secondary-500) 50%,
    var(--accent-500) 100%
  );
  min-height: 100vh;
  color: var(--gray-900);
  line-height: 1.6;
  font-feature-settings: "cv11", "ss01";
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem;
}

.header {
  text-align: center;
  margin-bottom: 3rem;
  color: var(--white);
}

.header h1 {
  font-size: clamp(2.5rem, 5vw, 3.5rem);
  font-weight: 800;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, #ffffff 0%, #f0f8ff 100%);
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.header p {
  font-size: 1.25rem;
  opacity: 0.95;
  font-weight: 400;
  max-width: 600px;
  margin: 0 auto;
}

.main-grid {
  display: grid;
  grid-template-columns: 1fr 400px;
  gap: 2rem;
  margin-bottom: 2rem;
}

.calculator-section {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.calculator-card {
  background: var(--white);
  border-radius: var(--radius-2xl);
  padding: 2.5rem;
  box-shadow: var(--shadow-2xl);
  border: 1px solid var(--gray-100);
  backdrop-filter: blur(20px);
  transition: all 0.3s ease;
}

.calculator-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 32px 64px -12px rgb(0 0 0 / 0.25);
}

.factors-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
}

.factor-group {
  background: linear-gradient(135deg, var(--gray-50) 0%, var(--white) 100%);
  padding: 2rem;
  border-radius: var(--radius-xl);
  border: 1px solid var(--gray-200);
  position: relative;
  overflow: hidden;
  transition: all 0.3s ease;
}

.factor-group::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-600), var(--secondary-500));
  transition: all 0.3s ease;
}

.factor-group.negative::before {
  background: linear-gradient(90deg, var(--error-500), var(--warning-500));
}

.factor-group:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary-200);
}

.factor-group h3 {
  color: var(--primary-700);
  margin-bottom: 1.5rem;
  font-size: 1.25rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.factor-group.negative h3 {
  color: var(--error-600);
}

.factor {
  margin-bottom: 1.5rem;
}

.factor:last-child {
  margin-bottom: 0;
}

.factor label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--gray-700);
  font-size: 0.95rem;
}

.factor-description {
  font-size: 0.875rem;
  color: var(--gray-500);
  margin-bottom: 1rem;
  line-height: 1.5;
}

.slider-container {
  display: flex;
  align-items: center;
  gap: 1rem;
  position: relative;
}

.slider-wrapper {
  flex: 1;
  position: relative;
  height: 2rem;
  display: flex;
  align-items: center;
}

.slider {
  width: 100%;
  height: 8px;
  border-radius: 50px;
  background: var(--gray-200);
  outline: none;
  -webkit-appearance: none;
  position: relative;
  cursor: pointer;
  transition: all 0.2s ease;
}

.slider:hover {
  background: var(--gray-300);
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-600), var(--primary-700));
  cursor: pointer;
  box-shadow: 0 4px 8px rgba(79, 70, 229, 0.3), 0 0 0 0 rgba(79, 70, 229, 0.4);
  transition: all 0.2s ease;
  border: 3px solid var(--white);
}

.slider::-webkit-slider-thumb:hover {
  transform: scale(1.1);
  box-shadow: 0 6px 12px rgba(79, 70, 229, 0.4),
    0 0 0 8px rgba(79, 70, 229, 0.1);
}

.slider::-webkit-slider-thumb:active {
  transform: scale(1.05);
  box-shadow: 0 2px 4px rgba(79, 70, 229, 0.3),
    0 0 0 12px rgba(79, 70, 229, 0.15);
}

.slider::-moz-range-thumb {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-600), var(--primary-700));
  cursor: pointer;
  border: 3px solid var(--white);
  box-shadow: 0 4px 8px rgba(79, 70, 229, 0.3);
  transition: all 0.2s ease;
}

.slider::-moz-range-thumb:hover {
  transform: scale(1.1);
}

.slider-value {
  background: linear-gradient(135deg, var(--primary-600), var(--primary-700));
  color: var(--white);
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-lg);
  font-weight: 700;
  font-size: 0.875rem;
  min-width: 3rem;
  text-align: center;
  box-shadow: var(--shadow-md);
  transition: all 0.2s ease;
}

.result-sidebar {
  position: sticky;
  top: 2rem;
  height: fit-content;
}

.result-section {
  background: linear-gradient(
    135deg,
    var(--primary-600) 0%,
    var(--secondary-600) 50%,
    var(--accent-600) 100%
  );
  border-radius: var(--radius-2xl);
  padding: 2.5rem;
  color: var(--white);
  text-align: center;
  box-shadow: var(--shadow-2xl);
  position: relative;
  overflow: hidden;
  transition: all 0.3s ease;
}

.result-section::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(
    circle at 30% 20%,
    rgba(255, 255, 255, 0.1) 0%,
    transparent 50%
  );
  pointer-events: none;
}

.result-section:hover {
  transform: translateY(-2px);
  box-shadow: 0 32px 64px -12px rgb(0 0 0 / 0.4);
}

.result-percentage {
  font-size: 4rem;
  font-weight: 900;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
  position: relative;
  z-index: 1;
  background: linear-gradient(135deg, #ffffff 0%, #f0f8ff 100%);
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%,
  100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.02);
  }
}

.result-message {
  font-size: 1.375rem;
  font-weight: 700;
  margin-bottom: 1rem;
  opacity: 0.95;
  position: relative;
  z-index: 1;
}

.result-advice {
  font-size: 1rem;
  background: rgba(255, 255, 255, 0.15);
  padding: 1.5rem;
  border-radius: var(--radius-xl);
  margin-top: 1.5rem;
  line-height: 1.6;
  border: 1px solid rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(10px);
  position: relative;
  z-index: 1;
}

.formula-section {
  background: var(--white);
  border-radius: var(--radius-2xl);
  overflow: hidden;
  box-shadow: var(--shadow-xl);
  border: 1px solid var(--gray-200);
  transition: all 0.3s ease;
}

.formula-section:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-2xl);
}

.formula-header {
  background: linear-gradient(135deg, var(--primary-600), var(--primary-700));
  color: var(--white);
  padding: 1.5rem 2rem;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: all 0.3s ease;
  border: none;
  font-size: 1.125rem;
  font-weight: 700;
}

.formula-header:hover {
  background: linear-gradient(135deg, var(--primary-700), var(--primary-800));
}

.formula-content {
  padding: 2.5rem;
  display: none;
  animation: fadeIn 0.3s ease-in-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.formula-content.show {
  display: block;
}

.formula-step {
  margin-bottom: 2rem;
  padding: 1.5rem;
  background: linear-gradient(135deg, var(--gray-50) 0%, var(--white) 100%);
  border-radius: var(--radius-xl);
  border: 1px solid var(--gray-200);
  transition: all 0.3s ease;
}

.formula-step:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-200);
}

.formula-step:last-child {
  margin-bottom: 0;
}

.formula-step h4 {
  color: var(--primary-700);
  margin-bottom: 0.75rem;
  font-size: 1.125rem;
  font-weight: 700;
}

.math-formula {
  background: var(--gray-100);
  padding: 1rem 1.5rem;
  border-radius: var(--radius-lg);
  font-family: "JetBrains Mono", "Fira Code", "Courier New", monospace;
  margin: 1rem 0;
  font-size: 1rem;
  border: 1px solid var(--gray-200);
  font-weight: 500;
  color: var(--gray-800);
}

.toggle-icon {
  transition: transform 0.3s ease;
  font-size: 1.25rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.2);
}

.toggle-icon.rotated {
  transform: rotate(180deg);
}

.footer {
  text-align: center;
  padding: 3rem 2rem;
  color: rgba(255, 255, 255, 0.9);
  font-size: 0.875rem;
}

.footer a {
  color: var(--white);
  text-decoration: none;
  font-weight: 600;
  transition: all 0.3s ease;
  padding: 0.25rem 0.5rem;
  border-radius: var(--radius-md);
}

.footer a:hover {
  color: var(--accent-300);
  text-decoration: underline;
  background: rgba(255, 255, 255, 0.1);
}

/* Responsive Design */
@media (max-width: 1024px) {
  .main-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .result-sidebar {
    position: static;
  }

  .factors-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
}

@media (max-width: 768px) {
  .container {
    padding: 1rem;
  }

  .calculator-card {
    padding: 1.5rem;
  }

  .factor-group {
    padding: 1.5rem;
  }

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

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

  .formula-content {
    padding: 1.5rem;
  }

  .footer {
    padding: 2rem 1rem;
  }

  .main-grid {
    gap: 1rem;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0.75rem;
  }

  .calculator-card {
    padding: 1rem;
  }

  .factor-group {
    padding: 1rem;
  }

  .result-section {
    padding: 1.5rem;
  }

  .slider-container {
    gap: 0.75rem;
  }

  .slider-value {
    padding: 0.375rem 0.5rem;
    font-size: 0.8rem;
    min-width: 2.5rem;
  }
}

/* Enhanced focus states for accessibility */
.slider:focus {
  outline: 2px solid var(--primary-600);
  outline-offset: 2px;
}

.formula-header:focus {
  outline: 2px solid var(--white);
  outline-offset: 2px;
}

/* Smooth scroll behavior */
html {
  scroll-behavior: smooth;
}

/* Loading animation for better perceived performance */
.calculator-card,
.result-section,
.formula-section {
  animation: slideInUp 0.6s ease-out;
}

@keyframes slideInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}