:root {
  --bg: #f7f9fc;
  --surface: #ffffff;
  --surface-alt: #f1f5f9;
  --text: #18212f;
  --text-soft: #425268;
  --border: #dbe3ec;
  --primary: #1e66f5;
  --primary-hover: #1553cf;
  --secondary: #e9eef6;
  --secondary-hover: #dde6f2;
  --success: #0f9d58;
  --warning-bg: #fff4f4;
  --warning-border: #d66;
  --shadow: 0 10px 30px rgba(20, 32, 51, 0.08);
  --radius: 16px;
  --radius-sm: 10px;
  --max-width: 1120px;
  --transition: 0.2s ease;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: Inter, "Segoe UI", Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img {
  max-width: 100%;
  display: block;
}

a {
  color: var(--primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.container {
  width: min(100% - 2rem, var(--max-width));
  margin-inline: auto;
}

.calculator-container {
  width: min(100% - 2rem, 1440px);
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(247, 249, 252, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(219, 227, 236, 0.8);
}

.header-inner {
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-logo {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--text);
  letter-spacing: -0.02em;
}

.site-logo:hover {
  text-decoration: none;
}

.site-logo-image {
  height: 52px;
  width: auto;
  display: block;
}

.main-nav ul,
.footer-links,
.related-links {
  margin: 0;
  padding: 0;
  list-style: none;
}

.main-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem 1.25rem;
}

.main-nav a {
  font-weight: 600;
  font-size: 1rem;
  color: var(--text-soft);
}

.main-nav a:hover,
.main-nav a[aria-current="page"] {
  color: var(--text);
  text-decoration: none;
}

.hero,
.page-hero,
.intro,
.featured-tools,
.why-use,
.how-it-works,
.international-support,
.assumptions,
.faq,
.final-cta,
.ad-slot-section,
.affiliate-section,
.assumptions-note,
.related-tools {
  padding: 3.75rem 0;
}

.hero {
  padding-top: 4.5rem;
  padding-bottom: 4rem;
}

.eyebrow {
  margin: 0 0 0.75rem;
  font-size: 0.85rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary);
}

h1,
h2,
h3,
legend,
summary {
  color: var(--text);
  letter-spacing: -0.02em;
}

h1 {
  margin: 0 0 1rem;
  font-size: clamp(2rem, 4vw, 3.4rem);
  line-height: 1.08;
}

h2 {
  margin: 0 0 1rem;
  font-size: clamp(1.5rem, 3vw, 2.1rem);
  line-height: 1.15;
}

h3 {
  margin: 0 0 0.6rem;
  font-size: 1.1rem;
  line-height: 1.25;
}

p {
  margin: 0 0 1rem;
  color: var(--text-soft);
}

.hero-text,
.page-intro {
  max-width: 760px;
  font-size: 1.1rem;
}

.hero-actions,
.form-actions,
.results-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  margin-top: 1.5rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0.85rem 1.25rem;
  border-radius: 999px;
  border: 1px solid transparent;
  font-weight: 700;
  line-height: 1;
  transition: background var(--transition), border-color var(--transition), transform var(--transition), color var(--transition);
  cursor: pointer;
  text-decoration: none;
}

.button:hover {
  text-decoration: none;
  transform: translateY(-1px);
}

.button-primary {
  background: var(--primary);
  color: #fff;
}

.button-primary:hover {
  background: var(--primary-hover);
}

.button-secondary {
  background: var(--secondary);
  color: var(--text);
  border-color: var(--border);
}

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

.trust-line {
  margin-top: 1rem;
  font-size: 0.95rem;
  color: var(--text-soft);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.25rem;
  margin-top: 1.5rem;
}

.card-grid.three-up {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.tool-card,
.info-card,
.step-card,
.sidebar-box,
.affiliate-box,
.ad-slot,
.results-panel,
.validation-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.tool-card,
.info-card,
.step-card,
.sidebar-box,
.affiliate-box,
.ad-slot {
  padding: 1.4rem;
}

.ad-slot {
  text-align: center;
  background: linear-gradient(180deg, #ffffff, #f8fbff);
  color: var(--text-soft);
}

.steps-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.25rem;
  margin-top: 1.5rem;
}

.breadcrumb {
  margin-bottom: 1rem;
  font-size: 0.95rem;
  color: var(--text-soft);
}

.breadcrumb a {
  color: var(--text-soft);
}

.calculator-section {
  padding: 1rem 0 3.75rem;
}

.calculator-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.7fr) minmax(420px, 1.1fr);
  gap: 2.25rem;
  align-items: start;
}

.calculator-form {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 2rem;
}

.calculator-form fieldset {
  margin: 0 0 1.5rem;
  padding: 1.1rem 1rem 0.25rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: #fcfdff;
}

.calculator-form fieldset:last-of-type {
  margin-bottom: 1rem;
}

.calculator-form legend {
  padding: 0 0.4rem;
  font-weight: 800;
  font-size: 1rem;
}

.form-row {
  margin-bottom: 1rem;
}

.form-row label {
  display: block;
  margin-bottom: 0.45rem;
  font-weight: 700;
  color: var(--text);
}

input,
select,
textarea {
  width: 100%;
  min-height: 48px;
  padding: 0.8rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: #fff;
  color: var(--text);
  font: inherit;
  transition: border-color var(--transition), box-shadow var(--transition), background var(--transition);
}

input:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: rgba(30, 102, 245, 0.7);
  box-shadow: 0 0 0 4px rgba(30, 102, 245, 0.12);
}

.field-help {
  display: block;
  margin-top: 0.35rem;
  font-size: 0.9rem;
  color: var(--text-soft);
}

.validation-box {
  padding: 1rem 1rem 0.8rem;
  margin-bottom: 1rem;
  background: var(--warning-bg);
  border-color: var(--warning-border);
}

.validation-box strong {
  display: block;
  margin-bottom: 0.35rem;
}

.validation-box ul {
  margin: 0.3rem 0 0;
  padding-left: 1.2rem;
  color: var(--text);
}

.results-panel {
  position: static;
  padding: 2rem;
}

.results-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.8rem;
  margin-top: 1.25rem;
}

.result-item {
  padding: 0.95rem 1rem;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface-alt);
}

.result-label {
  display: block;
  margin-bottom: 0.3rem;
  font-size: 0.95rem;
  color: var(--text-soft);
}

.result-item strong {
  font-size: 1.3rem;
  color: var(--text);
  font-weight: 800;
}

.assumptions-used {
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-size: 0.95rem;
  color: var(--text-soft);
}

.assumptions-used ul {
  margin: 0.35rem 0 0;
  padding-left: 1.1rem;
}

.related-links {
  display: grid;
  gap: 0.6rem;
  margin-top: 1rem;
}

.related-links a {
  display: inline-block;
  font-weight: 600;
}

.faq-list {
  display: grid;
  gap: 0.9rem;
  margin-top: 1.25rem;
}

details {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 1rem 1.1rem;
  box-shadow: var(--shadow);
}

summary {
  cursor: pointer;
  font-weight: 700;
  list-style: none;
}

summary::-webkit-details-marker {
  display: none;
}

details p {
  margin-top: 0.8rem;
  margin-bottom: 0;
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 2rem 0 3rem;
  background: #f4f7fb;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem 1.25rem;
  margin-bottom: 1rem;
}

.footer-links a {
  color: var(--text-soft);
  font-weight: 600;
}

.footer-copy {
  margin: 0;
  font-size: 0.95rem;
}

@media (max-width: 960px) {
  .card-grid,
  .card-grid.three-up,
  .steps-grid,
  .calculator-layout {
    grid-template-columns: 1fr;
  }

  .results-panel {
    position: static;
  }
}

@media (max-width: 760px) {
  .header-inner {
    flex-direction: column;
    align-items: flex-start;
    padding: 0.85rem 0;
  }

  .main-nav ul {
    gap: 0.75rem 1rem;
  }

  .hero,
  .page-hero,
  .intro,
  .featured-tools,
  .why-use,
  .how-it-works,
  .international-support,
  .assumptions,
  .faq,
  .final-cta,
  .ad-slot-section,
  .affiliate-section,
  .assumptions-note,
  .related-tools {
    padding: 3rem 0;
  }

  .calculator-form,
  .results-panel {
    padding: 1.15rem;
  }

  .tool-card,
  .info-card,
  .step-card,
  .sidebar-box,
  .affiliate-box,
  .ad-slot {
    padding: 1.15rem;
  }

  .button {
    width: 100%;
  }
}

@media print {
  body {
    background: #fff;
    color: #000;
  }

  .site-header,
  .main-nav,
  .hero-actions,
  .form-actions,
  .results-actions,
  .site-footer,
  .sidebar-box,
  .affiliate-section,
  .ad-slot-section,
  .related-tools,
  .faq {
    display: none !important;
  }

  .calculator-layout {
    display: block;
  }

  .calculator-form,
  .results-panel,
  .validation-box {
    box-shadow: none;
    border: 1px solid #ccc;
    background: #fff;
  }

  a {
    color: #000;
    text-decoration: none;
  }
}