html {
  scroll-behavior: smooth;
  font-size: 16px;
}

/* Constants */
:root {
  --primary-color: #0f172a;
  /* Deep Navy Blue */
  --secondary-color: #3b82f6;
  /* Vivid Blue */
  --accent-color: #10b981;
  /* Success Green */
  --text-color: #334155;
  /* Slate 700 */
  --bg-color: #f1f5f9;
  /* Slate 100 */
  --card-bg: #ffffff;
  --font-main: 'Inter', system-ui, -apple-system, sans-serif;
  --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);
  --radius: 0.75rem;
}

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

body {
  font-family: var(--font-main);
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  text-decoration: none;
  color: inherit;
}

/* Header */
header {
  background-color: var(--card-bg);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 50;
  padding: 1rem 0;
}

.container {
  max-width: 1024px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.nav-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo-container {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.logo-img {
  height: 90px;
  width: auto;
}

.site-title {
  font-weight: 800;
  font-size: 1.25rem;
  color: var(--primary-color);
  letter-spacing: -0.025em;
  text-transform: uppercase;
}

.main-nav ul {
  display: flex;
  list-style: none;
  gap: 2rem;
  padding: 0;
  margin: 0;
}

.main-nav a {
  text-decoration: none;
  color: var(--text-color);
  font-weight: 600;
  transition: color 0.2s;
}

.main-nav a:hover {
  color: var(--secondary-color);
}

/* Hero Section */
.hero {
  padding: 4rem 0 2rem;
  text-align: center;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 800;
  color: var(--primary-color);
  margin-bottom: 1rem;
  line-height: 1.1;
}

.hero p {
  font-size: 1.125rem;
  color: #64748b;
  max-width: 600px;
  margin: 0 auto;
}

/* Simulator Card */
.simulator-section {
  padding: 2rem 0 4rem;
}

.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  padding: 2rem;
  max-width: 800px;
  margin: 0 auto;
  border: 1px solid rgba(255, 255, 255, 0.5);
}

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

@media (min-width: 768px) {
  .simulator-grid {
    grid-template-columns: 1fr 1fr;
    align-items: start;
  }
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--primary-color);
}

.input-wrapper {
  position: relative;
}

.input-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: #94a3b8;
}

input[type="number"] {
  width: 100%;
  padding: 0.875rem 1rem 0.875rem 2.5rem;
  border: 2px solid #e2e8f0;
  border-radius: 0.5rem;
  font-size: 1rem;
  font-family: inherit;
  transition: all 0.2s;
  outline: none;
}

input[type="number"]:focus {
  border-color: var(--secondary-color);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.calculate-btn {
  display: block;
  width: 100%;
  background-color: var(--secondary-color);
  color: white;
  font-weight: 700;
  padding: 1rem;
  border: none;
  border-radius: 0.5rem;
  cursor: pointer;
  transition: background-color 0.2s;
  font-size: 1rem;
  margin-top: 1rem;
}

.calculate-btn:hover {
  background-color: #2563eb;
}

/* Results Area */
.results-area {
  background-color: #f8fafc;
  border-radius: 0.5rem;
  padding: 1.5rem;
  border: 1px solid #e2e8f0;
}

.result-item {
  margin-bottom: 1.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid #e2e8f0;
}

.result-item:last-child {
  margin-bottom: 0;
  padding-bottom: 0;
  border-bottom: none;
}

.result-label {
  font-size: 0.875rem;
  color: #64748b;
  margin-bottom: 0.25rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-weight: 600;
}

.result-value {
  font-size: 2rem;
  font-weight: 800;
  color: var(--primary-color);
}

.result-value.highlight {
  color: var(--secondary-color);
}

.result-value.success {
  color: var(--accent-color);
}

.hidden {
  display: none;
}

/* FAQ Section */
.faq-section {
  padding: 4rem 0;
  background-color: white;
}

.section-title {
  text-align: center;
  font-size: 2rem;
  font-weight: 800;
  color: var(--primary-color);
  margin-bottom: 3rem;
}

.accordion {
  max-width: 800px;
  margin: 0 auto;
}

.accordion-item {
  border-bottom: 1px solid #e2e8f0;
}

.accordion-button {
  width: 100%;
  text-align: left;
  padding: 1.5rem 0;
  background: none;
  border: none;
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--primary-color);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.accordion-button:hover {
  color: var(--secondary-color);
}

.icon {
  transition: transform 0.3s ease;
}

.accordion-button[aria-expanded="true"] .icon {
  transform: rotate(180deg);
}

.accordion-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease-out;
}

.accordion-body {
  padding-bottom: 1.5rem;
  color: #475569;
}

/* SEO Content Section */
.seo-section {
  padding: 4rem 0;
  background-color: var(--bg-color);
}

.seo-content {
  max-width: 800px;
  margin: 0 auto;
  background: white;
  padding: 2.5rem;
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}

.seo-content h2 {
  font-size: 1.5rem;
  color: var(--primary-color);
  margin-top: 2rem;
  margin-bottom: 1rem;
}

.seo-content h2:first-child {
  margin-top: 0;
}

.seo-content p {
  margin-bottom: 1rem;
  color: #475569;
}

/* Footer */
footer {
  background-color: var(--primary-color);
  color: white;
  padding: 3rem 0;
  text-align: center;
}

.footer-text {
  opacity: 0.8;
  font-size: 0.875rem;
}

/* Burger Menu */
.burger-menu {
  display: none;
  cursor: pointer;
  flex-direction: column;
  gap: 5px;
}

.burger-menu span {
  display: block;
  width: 25px;
  height: 3px;
  background-color: var(--primary-color);
  transition: all 0.3s ease;
}

@media (max-width: 768px) {
  .burger-menu {
    display: flex;
  }

  .main-nav {
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background-color: white;
    border-top: 1px solid #e2e8f0;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    transform: translateY(-200%);
    /* Hidden by default */
    transition: transform 0.3s ease-in-out;
    z-index: 999;
  }

  .main-nav.active {
    transform: translateY(0);
  }

  .main-nav ul {
    flex-direction: column;
    padding: 1rem;
    gap: 1rem;
    align-items: center;
  }
}

@media (max-width: 640px) {
  .hero h1 {
    font-size: 2rem;
  }

  .card {
    padding: 1.5rem;
  }

  .logo-img {
    height: 40px;
  }

  .site-title {
    font-size: 1.1rem;
  }
}