/* Base Reset & Variables */
:root {
  --color-primary: #FF6B35;
  --color-primary-dark: #E55A2B;
  --color-secondary: #004E64;
  --color-bg: #F9F9F9;
  --color-surface: #FFFFFF;
  --color-text: #1A1A1A;
  --color-text-light: #666666;
  --color-border: #E0E0E0;
  --radius: 12px;
  --shadow: 0 4px 20px rgba(0,0,0,0.08);
  --transition: 0.2s ease;
  --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

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

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

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(8px);
}

.site-header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 64px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-secondary);
}

.logo-text {
  letter-spacing: -0.5px;
}

.main-nav {
  display: flex;
  gap: 24px;
}

.main-nav a {
  color: var(--color-text);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  transition: color var(--transition);
}

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

/* Hero */
.hero {
  background: linear-gradient(135deg, #004E64 0%, #002B36 100%);
  color: #FFFFFF;
  padding: 80px 0;
  text-align: center;
}

.hero h1 {
  font-size: 2.8rem;
  font-weight: 800;
  margin-bottom: 16px;
  letter-spacing: -0.5px;
}

.hero-subtitle {
  font-size: 1.2rem;
  max-width: 600px;
  margin: 0 auto 32px;
  opacity: 0.9;
}

.btn-primary {
  display: inline-block;
  background: var(--color-primary);
  color: white;
  padding: 14px 32px;
  border-radius: 50px;
  text-decoration: none;
  font-weight: 600;
  font-size: 1.1rem;
  transition: background var(--transition), transform var(--transition);
  box-shadow: 0 4px 14px rgba(255,107,53,0.3);
}

.btn-primary:hover {
  background: var(--color-primary-dark);
  transform: translateY(-2px);
}

/* Calculator Section */
.calculator-section {
  padding: 60px 0;
}

.calculator-section h2 {
  text-align: center;
  font-size: 2rem;
  margin-bottom: 32px;
  color: var(--color-secondary);
}

.calculator-card {
  background: var(--color-surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 32px;
  max-width: 600px;
  margin: 0 auto;
}

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

.input-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--color-secondary);
}

.input-with-unit {
  display: flex;
  align-items: center;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  overflow: hidden;
  transition: border-color var(--transition);
}

.input-with-unit:focus-within {
  border-color: var(--color-primary);
}

.input-with-unit input {
  flex: 1;
  border: none;
  padding: 12px 16px;
  font-size: 1rem;
  outline: none;
  background: transparent;
}

.input-with-unit .unit {
  padding: 0 16px;
  font-weight: 600;
  color: var(--color-text-light);
  background: #f0f0f0;
  height: 100%;
  display: flex;
  align-items: center;
}

select {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  font-size: 1rem;
  background: white;
  outline: none;
  transition: border-color var(--transition);
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23333' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 16px center;
}

select:focus {
  border-color: var(--color-primary);
}

.btn-calculate {
  width: 100%;
  background: var(--color-primary);
  color: white;
  border: none;
  padding: 14px;
  border-radius: 8px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background var(--transition);
  margin-top: 8px;
}

.btn-calculate:hover {
  background: var(--color-primary-dark);
}

.result {
  margin-top: 24px;
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  justify-content: center;
}

.result-card {
  background: #f0f7fb;
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  flex: 1;
  min-width: 120px;
}

.pressure-value {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--color-secondary);
  line-height: 1;
}

.pressure-unit {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text-light);
}

.pressure-detail {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin-top: 4px;
}

.result-note {
  width: 100%;
  text-align: center;
  font-size: 0.95rem;
  color: var(--color-text-light);
  margin-top: 8px;
}

/* How It Works */
.how-it-works {
  background: var(--color-surface);
  padding: 60px 0;
}

.how-it-works h2 {
  text-align: center;
  font-size: 2rem;
  margin-bottom: 40px;
  color: var(--color-secondary);
}

.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 32px;
}

.step {
  text-align: center;
  padding: 24px;
}

.step-icon {
  margin-bottom: 16px;
}

.step h3 {
  font-size: 1.3rem;
  margin-bottom: 12px;
  color: var(--color-secondary);
}

.step p {
  color: var(--color-text-light);
}

/* Tips Section */
.tips-section {
  padding: 60px 0;
}

.tips-section h2 {
  text-align: center;
  font-size: 2rem;
  margin-bottom: 40px;
  color: var(--color-secondary);
}

.tips-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.tip-card {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  transition: transform var(--transition);
}

.tip-card:hover {
  transform: translateY(-4px);
}

.tip-card h3 {
  color: var(--color-primary);
  margin-bottom: 12px;
  font-size: 1.3rem;
}

.tip-card p {
  color: var(--color-text-light);
  line-height: 1.7;
}

/* FAQ */
.faq-section {
  background: var(--color-surface);
  padding: 60px 0;
}

.faq-section h2 {
  text-align: center;
  font-size: 2rem;
  margin-bottom: 40px;
  color: var(--color-secondary);
}

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

.faq-item {
  border-bottom: 1px solid var(--color-border);
  padding: 16px 0;
}

.faq-item summary {
  font-weight: 600;
  font-size: 1.1rem;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--color-secondary);
}

.faq-item summary::after {
  content: "+";
  font-size: 1.5rem;
  color: var(--color-primary);
  transition: transform var(--transition);
}

.faq-item[open] summary::after {
  content: "−";
}

.faq-item p {
  margin-top: 12px;
  color: var(--color-text-light);
  line-height: 1.7;
}

/* Ad slot */
.ad-slot {
  max-width: 720px;
  margin: 40px auto;
  padding: 0 20px;
  text-align: center;
}

/* Footer */
.site-footer {
  background: var(--color-secondary);
  color: white;
  padding: 32px 0;
  text-align: center;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.footer-links a {
  color: rgba(255,255,255,0.8);
  text-decoration: none;
  transition: color var(--transition);
}

.footer-links a:hover {
  color: var(--color-primary);
}

.footer-copy {
  font-size: 0.9rem;
  opacity: 0.7;
}

/* Responsive */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2rem;
  }
  .hero-subtitle {
    font-size: 1rem;
  }
  .main-nav {
    display: none;
  }
  .calculator-card {
    padding: 24px;
  }
  .steps, .tips-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .hero {
    padding: 40px 0;
  }
  .pressure-value {
    font-size: 2rem;
  }
}



/* Factory-injected deployment helpers. The AI owns the site design above this block. */
.ad-unit {
  width: min(100%, 720px);
  min-height: 120px;
  margin: 24px auto;
  display: block;
}

.legal-page {
  width: min(900px, calc(100% - 32px));
  margin: 40px auto;
}

.site-utility-links {
  width: min(900px, calc(100% - 32px));
  margin: 32px auto;
  padding-top: 16px;
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  border-top: 1px solid rgba(127, 127, 127, 0.25);
  font-size: 0.9rem;
}

.site-utility-links a {
  color: inherit;
  opacity: 0.75;
}