:root {
  --color-bg: #f7f9fc;
  --color-surface: #ffffff;
  --color-surface-soft: #eef4fb;
  --color-text: #172033;
  --color-muted: #607086;
  --color-border: #d8e1ec;
  --color-primary: #1665d8;
  --color-primary-dark: #0f4fa8;
  --color-success: #0f7a4f;
  --color-warning: #a76000;
  --color-danger: #b42318;
  --shadow: 0 12px 28px rgba(23, 32, 51, 0.08);
  --radius: 8px;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-7: 3rem;
  --max-width: 1120px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: Arial, Helvetica, sans-serif;
  font-size: 16px;
  line-height: 1.65;
}

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

a:hover {
  text-decoration: underline;
}

.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 20;
}

.nav-wrap,
.container {
  width: min(100% - 32px, var(--max-width));
  margin: 0 auto;
}

.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding: var(--space-4) 0;
}

.brand {
  color: var(--color-text);
  font-size: 1.12rem;
  font-weight: 700;
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  justify-content: flex-end;
}

.site-nav a {
  border-radius: var(--radius);
  color: var(--color-muted);
  font-weight: 600;
  padding: 0.35rem 0.6rem;
}

.site-nav a:hover,
.site-nav a:focus {
  background: var(--color-surface-soft);
  color: var(--color-primary);
  text-decoration: none;
}

main {
  padding: var(--space-6) 0 var(--space-7);
}

.hero {
  background: linear-gradient(180deg, #ffffff 0%, #eef4fb 100%);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-7) 0;
}

.hero .container {
  display: grid;
  gap: var(--space-5);
}

.hero-copy {
  max-width: 760px;
}

h1,
h2,
h3 {
  letter-spacing: 0;
  line-height: 1.2;
}

h1 {
  font-size: clamp(2rem, 4vw, 3.25rem);
  margin: 0 0 var(--space-4);
}

h2 {
  font-size: clamp(1.45rem, 2.5vw, 2rem);
  margin: var(--space-7) 0 var(--space-4);
}

h3 {
  font-size: 1.15rem;
  margin: var(--space-5) 0 var(--space-2);
}

p {
  margin: 0 0 var(--space-4);
}

.lead {
  color: var(--color-muted);
  font-size: 1.12rem;
  max-width: 760px;
}

.button,
button {
  align-items: center;
  background: var(--color-primary);
  border: 1px solid var(--color-primary);
  border-radius: var(--radius);
  color: #fff;
  cursor: pointer;
  display: inline-flex;
  font: inherit;
  font-weight: 700;
  justify-content: center;
  min-height: 44px;
  padding: 0.7rem 1rem;
}

.button:hover,
button:hover {
  background: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
  color: #fff;
  text-decoration: none;
}

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

.button.secondary:hover,
button.secondary:hover {
  background: var(--color-surface-soft);
  color: var(--color-text);
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin-top: var(--space-4);
}

.grid {
  display: grid;
  gap: var(--space-4);
}

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

.grid.two {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.card,
.tool-panel,
.result-panel,
.note,
.toc,
.faq-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}

.card,
.note,
.toc,
.faq-item {
  padding: var(--space-5);
}

.card h3 {
  margin-top: 0;
}

.card p:last-child,
.note p:last-child,
.faq-item p:last-child {
  margin-bottom: 0;
}

.tool-layout {
  display: grid;
  gap: var(--space-5);
  grid-template-columns: minmax(0, 1.12fr) minmax(300px, 0.88fr);
  align-items: start;
  margin-top: var(--space-5);
}

.tool-panel,
.result-panel {
  box-shadow: var(--shadow);
  padding: var(--space-5);
}

.tool-layout .result-panel {
  position: sticky;
  top: 92px;
}

.form-grid {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.field {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.field.full {
  grid-column: 1 / -1;
}

label {
  color: var(--color-text);
  font-weight: 700;
}

input,
select,
textarea {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  color: var(--color-text);
  font: inherit;
  min-height: 44px;
  padding: 0.65rem 0.75rem;
  width: 100%;
}

textarea {
  min-height: 150px;
  resize: vertical;
}

input:focus,
select:focus,
textarea:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(22, 101, 216, 0.14);
  outline: none;
}

.contact-shell {
  margin: 0 auto;
  max-width: 760px;
}

.contact-card {
  box-shadow: var(--shadow);
  margin-top: var(--space-5);
}

.contact-card .field {
  margin-bottom: var(--space-4);
}

.contact-card button {
  width: 100%;
}

.direct-email {
  color: var(--color-muted);
  font-size: 0.92rem;
  margin: var(--space-3) 0 0;
  text-align: center;
}

.field-hint,
.small,
.breadcrumbs {
  color: var(--color-muted);
  font-size: 0.92rem;
}

.breadcrumbs {
  margin-bottom: var(--space-4);
}

.tool-group {
  border-top: 1px solid var(--color-border);
  margin-top: var(--space-5);
  padding-top: var(--space-5);
}

.tool-group h2,
.result-panel h2 {
  font-size: 1.35rem;
  margin: 0 0 var(--space-4);
}

.results-list {
  display: grid;
  gap: var(--space-2);
  margin: 0;
}

.result-row {
  border-bottom: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  gap: var(--space-4);
  padding: var(--space-2) 0;
}

.result-row strong {
  text-align: right;
}

.result-row.highlight strong {
  color: var(--color-success);
  font-size: 1.2rem;
}

.message {
  border-radius: var(--radius);
  margin-top: var(--space-4);
  padding: var(--space-3) var(--space-4);
}

.message.error {
  background: #fff0ed;
  border: 1px solid #ffd0c7;
  color: var(--color-danger);
}

.message.warning {
  background: #fff7e8;
  border: 1px solid #ffdf9c;
  color: var(--color-warning);
}

.message.success {
  background: #eaf8f1;
  border: 1px solid #bfe8d3;
  color: var(--color-success);
}

.table-wrap {
  overflow-x: auto;
  width: 100%;
}

table {
  border-collapse: collapse;
  min-width: 880px;
  width: 100%;
}

th,
td {
  border-bottom: 1px solid var(--color-border);
  padding: 0.75rem;
  text-align: left;
  vertical-align: top;
}

th {
  background: var(--color-surface-soft);
  color: var(--color-text);
  font-weight: 700;
}

tr.best-profit td {
  background: #eaf8f1;
}

tr.best-margin td {
  background: #edf4ff;
}

tr.loss td {
  color: var(--color-danger);
}

.comparison-product {
  background: var(--color-surface-soft);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  margin-bottom: var(--space-4);
  padding: var(--space-4);
}

.comparison-product h3 {
  margin-top: 0;
}

.toc ul,
.link-list {
  margin: 0;
  padding-left: 1.2rem;
}

.faq-item {
  margin-bottom: var(--space-3);
}

.site-footer {
  background: var(--color-text);
  color: #d9e4f0;
  padding: var(--space-6) 0;
}

.footer-grid {
  display: grid;
  gap: var(--space-5);
  grid-template-columns: 1.2fr 1fr 1fr;
}

.site-footer a {
  color: #ffffff;
}

.footer-links {
  display: grid;
  gap: var(--space-2);
}

.disclaimer-box {
  background: #fff7e8;
  border: 1px solid #ffdf9c;
  border-radius: var(--radius);
  color: #4d3300;
  padding: var(--space-4);
}

@media (max-width: 840px) {
  .nav-wrap,
  .site-nav,
  .footer-grid,
  .tool-layout,
  .grid.two,
  .grid.three {
    grid-template-columns: 1fr;
  }

  .nav-wrap {
    align-items: flex-start;
    flex-direction: column;
  }

  .site-nav {
    justify-content: flex-start;
  }

  .tool-layout {
    display: block;
  }

  .result-panel {
    margin-top: var(--space-5);
    position: static;
  }
}

@media (max-width: 640px) {
  .nav-wrap,
  .container {
    width: min(100% - 24px, var(--max-width));
  }

  main {
    padding-top: var(--space-5);
  }

  .hero {
    padding: var(--space-6) 0;
  }

  .form-grid {
    grid-template-columns: 1fr;
  }

  .card,
  .tool-panel,
  .result-panel,
  .note,
  .toc,
  .faq-item {
    padding: var(--space-4);
  }

  .button,
  button {
    width: 100%;
  }

  .button-row {
    align-items: stretch;
    flex-direction: column;
  }
}