/* =========================================================
   Flat Feet Shoe Guide — Core Stylesheet
   Mobile-first, no external fonts/frameworks, CWV-optimized.
   ========================================================= */

/* ---------- Design tokens ---------- */
:root {
  --color-primary: #0d6e6e;
  --color-primary-dark: #084f4f;
  --color-primary-light: #e6f2f1;
  --color-accent: #d9791f;
  --color-accent-dark: #b5620f;
  --color-text: #202a2c;
  --color-text-muted: #55666a;
  --color-bg: #ffffff;
  --color-bg-alt: #f6f9f9;
  --color-border: #e0e8e7;
  --color-success: #1f7a4d;
  --color-warn: #a34a1a;
  --color-star: #d9791f;

  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-heading: Georgia, "Times New Roman", ui-serif, serif;

  --max-width: 1160px;
  --radius: 10px;
  --radius-sm: 6px;
  --shadow-sm: 0 1px 3px rgba(15, 40, 40, 0.08);
  --shadow-md: 0 4px 16px rgba(15, 40, 40, 0.10);
  --space-1: 0.5rem;
  --space-2: 1rem;
  --space-3: 1.5rem;
  --space-4: 2rem;
  --space-5: 3rem;
  --space-6: 4.5rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-primary: #2ba39a;
    --color-primary-dark: #1c7a73;
    --color-primary-light: #0f2727;
    --color-accent: #e79038;
    --color-accent-dark: #c97a24;
    --color-text: #e8edec;
    --color-text-muted: #a6b4b3;
    --color-bg: #12181a;
    --color-bg-alt: #182121;
    --color-border: #2a3535;
    --color-success: #3fbf82;
    --color-warn: #e08a4d;
    --color-star: #e79038;
  }
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }
body, h1, h2, h3, h4, p, figure, blockquote, dl, dd, ul, ol { margin: 0; }
ul[class], ol[class] { list-style: none; padding: 0; }
img, picture, svg { max-width: 100%; display: block; }
input, button, textarea, select { font: inherit; }
a { color: inherit; }

html {
  scroll-behavior: smooth;
  color-scheme: light dark;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  font-size: 1.0625rem;
}

h1, h2, h3, h4 {
  font-family: var(--font-heading);
  line-height: 1.2;
  color: var(--color-text);
  font-weight: 700;
}
h1 { font-size: clamp(1.9rem, 4vw, 2.7rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); margin-bottom: var(--space-2); }
h3 { font-size: 1.25rem; margin-bottom: var(--space-1); }

p { margin-bottom: var(--space-2); color: var(--color-text); }
p.lede { font-size: 1.15rem; color: var(--color-text-muted); }

a { text-decoration: underline; text-decoration-color: var(--color-border); text-underline-offset: 2px; }
main a:not(.btn):hover { text-decoration-color: currentColor; }

/* Focus visibility for accessibility */
a:focus-visible, button:focus-visible, input:focus-visible, textarea:focus-visible, summary:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 2px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--color-primary-dark);
  color: #fff;
  padding: 0.75rem 1.25rem;
  z-index: 200;
  border-radius: 0 0 var(--radius-sm) 0;
  text-decoration: none;
}
.skip-link:focus { left: 0; }

/* ---------- Layout helpers ---------- */
.container {
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: var(--space-2);
}
.section { padding-block: var(--space-5); }
.section-alt { background: var(--color-bg-alt); }
.section-tight { padding-block: var(--space-4); }
.text-center { text-align: center; }
.muted { color: var(--color-text-muted); }
.visually-hidden {
  position: absolute; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0 0 0 0); white-space: nowrap; border: 0; padding: 0; margin: -1px;
}

/* ---------- Header / Nav ---------- */
.site-header {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
  position: sticky;
  top: 0;
  z-index: 100;
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 68px;
  gap: var(--space-2);
}
.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.2rem;
  text-decoration: none;
  color: var(--color-text);
  white-space: nowrap;
}
.brand svg { flex: none; }
.brand .brand-sub { display: block; font-family: var(--font-body); font-weight: 400; font-size: 0.68rem; color: var(--color-text-muted); letter-spacing: 0.03em; }

.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 0.5rem 0.75rem;
  cursor: pointer;
  color: var(--color-text);
}
.nav-toggle .bar { width: 18px; height: 2px; background: currentColor; display: block; position: relative; }
.nav-toggle .bar::before, .nav-toggle .bar::after { content: ""; position: absolute; left: 0; width: 18px; height: 2px; background: currentColor; }
.nav-toggle .bar::before { top: -6px; }
.nav-toggle .bar::after { top: 6px; }

.main-nav { display: none; }
.main-nav.is-open { display: block; }
.main-nav ul {
  display: flex;
  flex-direction: column;
  border-top: 1px solid var(--color-border);
  list-style: none;
  padding: 0;
  margin: 0;
}
.main-nav a {
  display: block;
  padding: var(--space-2) 0;
  text-decoration: none;
  font-weight: 600;
  border-bottom: 1px solid var(--color-border);
}
.main-nav { position: absolute; left: 0; right: 0; top: 100%; background: var(--color-bg); padding: 0 var(--space-2) var(--space-2); box-shadow: var(--shadow-md); }

@media (min-width: 860px) {
  .nav-toggle { display: none; }
  .main-nav { display: block; position: static; box-shadow: none; padding: 0; background: transparent; }
  .main-nav ul { flex-direction: row; gap: var(--space-3); border-top: none; }
  .main-nav a { padding: 0; border-bottom: none; font-weight: 600; text-decoration: none; }
  .main-nav a[aria-current="page"] { color: var(--color-primary-dark); }
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.8rem 1.4rem;
  border-radius: var(--radius-sm);
  font-weight: 700;
  text-decoration: none;
  border: 2px solid transparent;
  cursor: pointer;
  font-size: 1rem;
  line-height: 1.2;
}
.btn-primary { background: var(--color-accent); color: #ffffff; }
.btn-primary:hover { background: var(--color-accent-dark); }
.btn-secondary { background: transparent; border-color: var(--color-primary); color: var(--color-primary-dark); }
.btn-secondary:hover { background: var(--color-primary-light); }
.btn-block { display: flex; width: 100%; }
.btn-sm { padding: 0.55rem 1rem; font-size: 0.9rem; }

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(180deg, var(--color-primary-light), var(--color-bg) 85%);
  padding-block: var(--space-6) var(--space-5);
}
.hero-grid {
  display: grid;
  gap: var(--space-4);
  align-items: center;
}
@media (min-width: 900px) {
  .hero-grid { grid-template-columns: 1.1fr 0.9fr; }
}
.trust-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  padding: 0.4rem 0.85rem;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-primary-dark);
  margin-bottom: var(--space-2);
}
.hero-ctas { display: flex; gap: var(--space-2); flex-wrap: wrap; margin-top: var(--space-3); }
.hero-photo-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-3);
  box-shadow: var(--shadow-md);
}
.hero-photo-card svg { width: 100%; height: auto; }

/* ---------- Cards / grids ---------- */
.grid { display: grid; gap: var(--space-3); }
.grid-2 { grid-template-columns: 1fr; }
.grid-3 { grid-template-columns: 1fr; }
.grid-4 { grid-template-columns: 1fr; }
@media (min-width: 640px) {
  .grid-2 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 900px) {
  .grid-3 { grid-template-columns: repeat(3, 1fr); }
  .grid-4 { grid-template-columns: repeat(4, 1fr); }
}

.card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-3);
  box-shadow: var(--shadow-sm);
}
.card h3 { margin-top: 0; }
.card-icon { color: var(--color-primary); margin-bottom: var(--space-1); }

.category-card {
  display: block;
  text-decoration: none;
  color: inherit;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-3);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.category-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }
.category-card .tag { display: inline-block; font-size: 0.75rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.05em; color: var(--color-primary-dark); background: var(--color-primary-light); padding: 0.2rem 0.55rem; border-radius: 999px; margin-bottom: 0.6rem; }
.category-card h3 { text-decoration: none; }

/* ---------- Product review block ---------- */
.product-card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-3);
  background: var(--color-bg);
  box-shadow: var(--shadow-sm);
  margin-bottom: var(--space-4);
}
.product-card-header {
  display: grid;
  gap: var(--space-3);
  margin-bottom: var(--space-2);
}
@media (min-width: 700px) {
  .product-card-header { grid-template-columns: 200px 1fr; align-items: start; }
}
.product-photo {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-2);
  display: flex;
  align-items: center;
  justify-content: center;
}
.rank-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  background: var(--color-primary);
  color: #fff;
  border-radius: 50%;
  font-weight: 700;
  font-family: var(--font-heading);
  margin-right: 0.5rem;
}
.rating { color: var(--color-star); font-weight: 700; letter-spacing: 0.05em; }
.spec-list { display: grid; grid-template-columns: auto 1fr; gap: 0.35rem 0.75rem; font-size: 0.95rem; margin: var(--space-2) 0; }
.spec-list dt { font-weight: 700; color: var(--color-text-muted); }
.spec-list dd { margin: 0; }

.pros-cons { display: grid; gap: var(--space-2); margin-block: var(--space-2); }
@media (min-width: 640px) { .pros-cons { grid-template-columns: 1fr 1fr; } }
.pros, .cons { border-radius: var(--radius-sm); padding: var(--space-2); }
.pros { background: color-mix(in srgb, var(--color-success) 10%, transparent); }
.cons { background: color-mix(in srgb, var(--color-warn) 10%, transparent); }
.pros h4, .cons h4 { font-family: var(--font-body); font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.04em; margin-bottom: 0.5rem; }
.pros h4 { color: var(--color-success); }
.cons h4 { color: var(--color-warn); }
.pros ul, .cons ul { list-style: none; padding: 0; margin: 0; display: grid; gap: 0.35rem; font-size: 0.95rem; }

.who-grid { display: grid; gap: var(--space-2); margin-block: var(--space-2); }
@media (min-width: 640px) { .who-grid { grid-template-columns: 1fr 1fr; } }
.who-grid > div { background: var(--color-bg-alt); border-radius: var(--radius-sm); padding: var(--space-2); }
.who-grid h4 { font-size: 0.95rem; margin-bottom: 0.4rem; }

.affiliate-cta { display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-2); margin-top: var(--space-2); }
.price-note { font-size: 0.85rem; color: var(--color-text-muted); }

/* ---------- Tables (comparisons) ---------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--color-border); border-radius: var(--radius); }
table.compare {
  width: 100%;
  border-collapse: collapse;
  min-width: 640px;
  font-size: 0.95rem;
}
table.compare th, table.compare td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--color-border);
  text-align: left;
  vertical-align: top;
}
table.compare thead th {
  background: var(--color-bg-alt);
  font-family: var(--font-heading);
  position: sticky;
  top: 0;
}
table.compare tbody tr:last-child td { border-bottom: none; }
table.compare tbody tr:hover { background: var(--color-bg-alt); }

/* ---------- FAQ / accordion ---------- */
.faq-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  margin-bottom: var(--space-1);
  overflow: hidden;
}
.faq-item summary {
  cursor: pointer;
  padding: var(--space-2);
  font-weight: 700;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-2);
  background: var(--color-bg);
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+";
  font-size: 1.4rem;
  line-height: 1;
  color: var(--color-primary);
  flex: none;
}
.faq-item[open] summary::after { content: "\2212"; }
.faq-item .faq-answer { padding: 0 var(--space-2) var(--space-2); color: var(--color-text-muted); }

/* ---------- Breadcrumbs ---------- */
.breadcrumbs { font-size: 0.85rem; color: var(--color-text-muted); padding-block: var(--space-2); }
.breadcrumbs ol { display: flex; flex-wrap: wrap; gap: 0.35rem; list-style: none; padding: 0; margin: 0; }
.breadcrumbs a { text-decoration: none; color: var(--color-text-muted); }
.breadcrumbs a:hover { text-decoration: underline; }
.breadcrumbs li:not(:last-child)::after { content: "/"; margin-left: 0.35rem; color: var(--color-border); }

/* ---------- Callouts ---------- */
.callout {
  border-left: 4px solid var(--color-primary);
  background: var(--color-primary-light);
  padding: var(--space-2) var(--space-3);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin-block: var(--space-3);
}
.callout.callout-warn { border-color: var(--color-warn); background: color-mix(in srgb, var(--color-warn) 10%, transparent); }
.callout strong { display: block; margin-bottom: 0.3rem; }

.disclosure-banner {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-2);
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin-block: var(--space-3);
}

/* ---------- Author / trust box ---------- */
.author-box {
  display: flex;
  gap: var(--space-2);
  align-items: flex-start;
  background: var(--color-bg-alt);
  border-radius: var(--radius);
  padding: var(--space-3);
  margin-block: var(--space-3);
}
.author-avatar { flex: none; width: 56px; height: 56px; border-radius: 50%; overflow: hidden; }
.author-box h4 { margin-bottom: 0.2rem; }
.author-box p { margin-bottom: 0; font-size: 0.95rem; }

/* ---------- Article content ---------- */
.article-body { max-width: 74ch; }
.article-body h2 { margin-top: var(--space-4); }
.article-body h3 { margin-top: var(--space-3); }
.article-body ul, .article-body ol { padding-left: 1.3rem; margin-bottom: var(--space-2); }
.article-body li { margin-bottom: 0.4rem; }
.article-meta { color: var(--color-text-muted); font-size: 0.9rem; margin-bottom: var(--space-3); }
.toc { background: var(--color-bg-alt); border-radius: var(--radius); padding: var(--space-3); margin-bottom: var(--space-3); max-width: 74ch; }
.toc h2 { font-size: 1.1rem; margin-bottom: 0.75rem; }
.toc ol { padding-left: 1.2rem; margin: 0; }
.toc li { margin-bottom: 0.3rem; }

/* ---------- Footer ---------- */
.site-footer {
  background: var(--color-primary-dark);
  color: #f0f5f4;
  padding-block: var(--space-5) var(--space-4);
  margin-top: var(--space-5);
}
.site-footer a { color: #dcece9; text-decoration: none; }
.site-footer a:hover { text-decoration: underline; }
.footer-grid { display: grid; gap: var(--space-3); grid-template-columns: 1fr; }
@media (min-width: 700px) {
  .footer-grid { grid-template-columns: 1.4fr 1fr 1fr; }
}
.footer-grid h2 { font-size: 1rem; color: #fff; margin-bottom: 0.75rem; }
.footer-grid ul { display: grid; gap: 0.5rem; list-style: none; padding: 0; margin: 0; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.15);
  margin-top: var(--space-4);
  padding-top: var(--space-3);
  font-size: 0.85rem;
  color: #b7cbc8;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  justify-content: space-between;
}

/* ---------- Misc ---------- */
.eyebrow { text-transform: uppercase; letter-spacing: 0.06em; font-size: 0.8rem; font-weight: 700; color: var(--color-primary-dark); }
.section-head { max-width: 68ch; margin-bottom: var(--space-4); }
hr.divider { border: none; border-top: 1px solid var(--color-border); margin-block: var(--space-4); }

.contact-form { display: grid; gap: var(--space-2); max-width: 560px; }
.contact-form label { font-weight: 700; display: block; margin-bottom: 0.35rem; }
.contact-form input, .contact-form textarea {
  width: 100%;
  padding: 0.7rem 0.9rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-bg);
  color: var(--color-text);
}
.contact-form textarea { min-height: 140px; resize: vertical; }

/* ---------- Size calculator ---------- */
.calculator {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-3);
  margin-block: var(--space-3);
}
.calc-form {
  display: grid;
  gap: var(--space-2);
  align-items: end;
  grid-template-columns: 1fr;
}
@media (min-width: 640px) {
  .calc-form { grid-template-columns: 1fr 1.3fr auto; }
}
.calc-field label { font-weight: 700; display: block; margin-bottom: 0.35rem; font-size: 0.9rem; }
.calc-field input, .calc-field select {
  width: 100%;
  padding: 0.7rem 0.9rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-bg);
  color: var(--color-text);
  font-size: 1rem;
}
.calc-result {
  margin-top: var(--space-3);
}
.calc-result-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-2);
}
@media (min-width: 640px) {
  .calc-result-grid { grid-template-columns: repeat(5, 1fr); }
}
.calc-result-item {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-2);
  text-align: center;
}
.calc-result-item .calc-label { display: block; font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.04em; color: var(--color-text-muted); margin-bottom: 0.3rem; }
.calc-result-item .calc-value { display: block; font-family: var(--font-heading); font-size: 1.4rem; font-weight: 700; color: var(--color-primary-dark); }
.calc-result-item.is-input { border-color: var(--color-primary); border-width: 2px; }
.calc-note { font-size: 0.85rem; color: var(--color-text-muted); margin-top: var(--space-2); }
.calc-error { color: var(--color-warn); font-weight: 600; margin-top: var(--space-2); }
.calc-result[hidden] { display: none; }

/* ---------- Glossary ---------- */
.glossary-list { max-width: 74ch; }
.glossary-list dt {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
  margin-top: var(--space-3);
  padding-top: var(--space-3);
  border-top: 1px solid var(--color-border);
}
.glossary-list dt:first-of-type { margin-top: 0; padding-top: 0; border-top: none; }
.glossary-list dd { margin: 0.4rem 0 0; color: var(--color-text-muted); }

/* ---------- Back to top ---------- */
.back-to-top {
  position: fixed;
  right: 1.25rem;
  bottom: 1.25rem;
  width: 3rem;
  height: 3rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--color-primary-dark);
  color: #fff;
  text-decoration: none;
  font-size: 1.3rem;
  box-shadow: var(--shadow-md);
  opacity: 0;
  transform: translateY(0.5rem);
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease;
  z-index: 90;
}
.back-to-top.is-visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}
.back-to-top:hover { background: var(--color-primary); }
@media (prefers-reduced-motion: reduce) {
  .back-to-top { transition: none; }
}