/* ============================================================
   Brand Size Matcher — Stylesheet
   Aesthetic: COS/Everlane/Aesop-inspired minimalism
   ============================================================ */

/* --- Custom Properties --- */
:root {
  --color-primary: #1A1A1A;
  --color-bg: #F5F5F5;
  --color-accent: #C7A17A;
  --color-text: #2D2D2D;
  --color-border: #E8E8E8;
  --color-white: #FFFFFF;
  --color-muted: #888888;
  --color-success: #4A7C59;
  --color-good: #6B8F3D;
  --color-approx: #C7A17A;
  --color-loose: #B0B0B0;

  --font-heading: 'Playfair Display', Georgia, serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;

  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.12);
  --shadow-hover: 0 8px 24px rgba(0,0,0,0.15);

  --transition-base: 0.2s ease;
  --transition-slow: 0.4s ease;

  --max-width: 1200px;
  --max-width-narrow: 800px;
}

/* --- Reset & Base --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.6;
  min-height: 100vh;
}

img { max-width: 100%; display: block; }
a { color: var(--color-primary); text-decoration: none; }
a:hover { color: var(--color-accent); }

h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.2;
  color: var(--color-primary);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 1.75rem; }
h3 { font-size: 1.25rem; }

/* --- Layout --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.container--narrow {
  max-width: var(--max-width-narrow);
}

/* --- Navigation --- */
.nav {
  background: var(--color-white);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.nav__brand {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: -0.02em;
}

.nav__links {
  display: flex;
  gap: var(--space-xl);
  list-style: none;
}

.nav__link {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-muted);
  transition: color var(--transition-base);
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.nav__link:hover,
.nav__link--active {
  color: var(--color-primary);
}

.nav__toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
}

.nav__toggle-bar {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-primary);
  margin: 4px 0;
  transition: var(--transition-base);
}

/* --- Hero --- */
.hero {
  text-align: center;
  padding: var(--space-4xl) var(--space-lg);
  background: var(--color-white);
}

.hero__title {
  font-size: 3.5rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-lg);
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
}

.hero__accent {
  color: var(--color-accent);
}

.hero__subtitle {
  font-size: 1.125rem;
  color: var(--color-muted);
  max-width: 500px;
  margin: 0 auto var(--space-2xl);
  line-height: 1.7;
}

.hero__cta {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  background: var(--color-primary);
  color: var(--color-white);
  padding: var(--space-md) var(--space-2xl);
  border-radius: var(--radius-md);
  font-size: 0.9375rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  transition: all var(--transition-base);
}

.hero__cta:hover {
  background: var(--color-accent);
  color: var(--color-white);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* --- Section --- */
.section {
  padding: var(--space-4xl) var(--space-lg);
}

.section--white {
  background: var(--color-white);
}

.section__title {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.section__label {
  display: block;
  font-family: var(--font-body);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-sm);
}

/* --- How It Works --- */
.steps {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
  max-width: var(--max-width);
  margin: 0 auto;
}

.step {
  text-align: center;
  padding: var(--space-xl);
}

.step__number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--color-primary);
  color: var(--color-white);
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: var(--space-md);
}

.step__title {
  margin-bottom: var(--space-sm);
}

.step__desc {
  color: var(--color-muted);
  font-size: 0.9375rem;
}

/* --- Brand Card Grid --- */
.brand-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
  max-width: var(--max-width);
  margin: 0 auto;
}

.brand-card {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  display: flex;
  align-items: center;
  gap: var(--space-md);
  cursor: pointer;
  transition: all var(--transition-base);
}

.brand-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
  border-color: var(--color-accent);
}

.brand-card--selected {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 2px var(--color-accent);
}

.brand-card__logo {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-white);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 0.875rem;
  flex-shrink: 0;
}

.brand-card__info { flex: 1; }

.brand-card__name {
  font-family: var(--font-body);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--color-primary);
}

.brand-card__origin {
  font-size: 0.8125rem;
  color: var(--color-muted);
}

/* --- Step Flow (App Page) --- */
.step-indicator {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-xl) 0;
}

.step-indicator__step {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.step-indicator__dot {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  border: 2px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-muted);
  transition: all var(--transition-base);
}

.step-indicator__dot--active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-white);
}

.step-indicator__dot--complete {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-white);
}

.step-indicator__label {
  font-size: 0.8125rem;
  color: var(--color-muted);
  display: none;
}

.step-indicator__line {
  width: 40px;
  height: 2px;
  background: var(--color-border);
  transition: background var(--transition-base);
}

.step-indicator__line--active {
  background: var(--color-accent);
}

/* --- Step Container --- */
.step-container {
  max-width: var(--max-width-narrow);
  margin: 0 auto;
  padding: 0 var(--space-lg) var(--space-4xl);
}

.step-panel {
  display: none;
  animation: fadeIn 0.3s ease;
}

.step-panel--active {
  display: block;
}

.step-panel__title {
  text-align: center;
  margin-bottom: var(--space-sm);
}

.step-panel__subtitle {
  text-align: center;
  color: var(--color-muted);
  margin-bottom: var(--space-2xl);
  font-size: 0.9375rem;
}

/* --- Size Buttons --- */
.size-grid {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
  justify-content: center;
}

.size-btn {
  min-width: 64px;
  padding: var(--space-md) var(--space-xl);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-white);
  font-family: var(--font-body);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  transition: all var(--transition-base);
}

.size-btn:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.size-btn--selected {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-white);
}

/* --- Category Buttons --- */
.category-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
  max-width: 400px;
  margin: 0 auto;
}

.category-btn {
  padding: var(--space-lg) var(--space-xl);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-white);
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 500;
  color: var(--color-text);
  cursor: pointer;
  transition: all var(--transition-base);
  text-align: center;
}

.category-btn:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.category-btn--selected {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-white);
}

/* --- Results --- */
.results {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}

.result-card {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  transition: all var(--transition-base);
  animation: slideUp 0.3s ease;
  animation-fill-mode: both;
}

.result-card:hover {
  box-shadow: var(--shadow-md);
}

.result-card__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-md);
}

.result-card__brand {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.result-card__logo {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-white);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 0.75rem;
  flex-shrink: 0;
}

.result-card__name {
  font-weight: 600;
  font-size: 1rem;
}

.result-card__size {
  font-size: 0.875rem;
  color: var(--color-muted);
}

.result-card__source {
  font-size: 0.75rem;
  color: var(--color-primary, #4f46e5);
  text-decoration: none;
  opacity: 0.8;
}
.result-card__source:hover {
  opacity: 1;
  text-decoration: underline;
}

.result-card__match {
  text-align: right;
}

.result-card__percentage {
  font-size: 1.5rem;
  font-weight: 700;
  font-family: var(--font-heading);
}

.result-card__percentage--excellent { color: var(--color-success); }
.result-card__percentage--good { color: var(--color-good); }
.result-card__percentage--approximate { color: var(--color-approx); }
.result-card__percentage--loose { color: var(--color-loose); }

.result-card__label {
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.result-card__label--excellent { color: var(--color-success); }
.result-card__label--good { color: var(--color-good); }
.result-card__label--approximate { color: var(--color-approx); }
.result-card__label--loose { color: var(--color-loose); }

/* --- Match Bar --- */
.match-bar {
  margin-top: var(--space-md);
}

.match-bar__track {
  height: 6px;
  background: var(--color-border);
  border-radius: 3px;
  overflow: hidden;
}

.match-bar__fill {
  height: 100%;
  border-radius: 3px;
  transition: width 0.6s ease;
  width: 0;
}

.match-bar__fill--excellent { background: var(--color-success); }
.match-bar__fill--good { background: var(--color-good); }
.match-bar__fill--approximate { background: var(--color-approx); }
.match-bar__fill--loose { background: var(--color-loose); }

/* --- Measurement Detail --- */
.measurement-detail {
  margin-top: var(--space-md);
  padding-top: var(--space-md);
  border-top: 1px solid var(--color-border);
  display: none;
}

.measurement-detail--open {
  display: block;
}

.measurement-detail__row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-xs) 0;
  font-size: 0.8125rem;
}

.measurement-detail__dim {
  text-transform: capitalize;
  color: var(--color-muted);
  flex: 1;
}

.measurement-detail__source,
.measurement-detail__match {
  flex: 1;
  text-align: center;
  font-variant-numeric: tabular-nums;
}

.measurement-detail__iou {
  flex: 0.5;
  text-align: right;
  font-weight: 600;
}

.result-card__toggle {
  display: block;
  width: 100%;
  margin-top: var(--space-md);
  padding: var(--space-sm);
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-size: 0.8125rem;
  color: var(--color-muted);
  cursor: pointer;
  transition: all var(--transition-base);
}

.result-card__toggle:hover {
  border-color: var(--color-accent);
  color: var(--color-text);
}

/* --- Back Button --- */
.back-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  background: none;
  border: none;
  font-family: var(--font-body);
  font-size: 0.875rem;
  color: var(--color-muted);
  cursor: pointer;
  padding: var(--space-sm) 0;
  margin-bottom: var(--space-lg);
  transition: color var(--transition-base);
}

.back-btn:hover {
  color: var(--color-primary);
}

/* --- Selection Summary --- */
.selection-summary {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-md);
  padding: var(--space-md) var(--space-lg);
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-xl);
  font-size: 0.875rem;
}

.selection-summary__item {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.selection-summary__label {
  color: var(--color-muted);
}

.selection-summary__value {
  font-weight: 600;
  color: var(--color-primary);
}

.selection-summary__separator {
  color: var(--color-border);
}

/* --- Footer --- */
.footer {
  background: var(--color-primary);
  color: rgba(255,255,255,0.6);
  padding: var(--space-2xl) var(--space-lg);
  text-align: center;
  font-size: 0.8125rem;
}

.footer a {
  color: var(--color-accent);
}

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

.footer__links {
  display: flex;
  justify-content: center;
  gap: var(--space-xl);
  list-style: none;
  margin-bottom: var(--space-md);
}

/* --- Disclaimer --- */
.disclaimer {
  font-size: 0.75rem;
  color: var(--color-muted);
  text-align: center;
  padding: var(--space-md);
  border-top: 1px solid var(--color-border);
  margin-top: var(--space-xl);
}

/* --- Static Content (About / Contribute) --- */
.content {
  max-width: var(--max-width-narrow);
  margin: 0 auto;
  padding: var(--space-3xl) var(--space-lg);
}

.content h1 {
  margin-bottom: var(--space-xl);
}

.content h2 {
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-md);
}

.content h3 {
  margin-top: var(--space-xl);
  margin-bottom: var(--space-sm);
}

.content p {
  margin-bottom: var(--space-md);
  line-height: 1.7;
}

.content ul, .content ol {
  margin-bottom: var(--space-md);
  padding-left: var(--space-xl);
}

.content li {
  margin-bottom: var(--space-sm);
  line-height: 1.6;
}

.content pre {
  background: var(--color-primary);
  color: #E0E0E0;
  padding: var(--space-lg);
  border-radius: var(--radius-md);
  overflow-x: auto;
  font-size: 0.8125rem;
  line-height: 1.6;
  margin-bottom: var(--space-md);
}

.content code {
  background: var(--color-border);
  padding: 0.15em 0.4em;
  border-radius: var(--radius-sm);
  font-size: 0.875em;
}

.content pre code {
  background: none;
  padding: 0;
}

.content table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: var(--space-md);
}

.content th, .content td {
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--color-border);
  text-align: left;
  font-size: 0.875rem;
}

.content th {
  background: var(--color-white);
  font-weight: 600;
}

/* --- Animations --- */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fillBar {
  from { width: 0; }
}

.animate-on-scroll {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.animate-on-scroll--visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- Loading --- */
.loading {
  text-align: center;
  padding: var(--space-3xl);
  color: var(--color-muted);
}

.loading__spinner {
  width: 32px;
  height: 32px;
  border: 3px solid var(--color-border);
  border-top-color: var(--color-accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: 0 auto var(--space-md);
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* --- Responsive: Tablet --- */
@media (min-width: 768px) {
  h1 { font-size: 3rem; }
  .hero__title { font-size: 4rem; }

  .steps { grid-template-columns: repeat(3, 1fr); }
  .brand-grid { grid-template-columns: repeat(3, 1fr); }

  .step-indicator__label { display: block; }

  .category-grid { grid-template-columns: repeat(3, 1fr); max-width: 100%; }

  .nav__toggle { display: none; }
  .nav__links { display: flex; }
}

/* --- Responsive: Desktop --- */
@media (min-width: 1024px) {
  .hero__title { font-size: 4.5rem; }
  .brand-grid { grid-template-columns: repeat(4, 1fr); }
}

@media (min-width: 1280px) {
  .brand-grid { grid-template-columns: repeat(4, 1fr); gap: var(--space-lg); }
}

/* --- Responsive: Mobile --- */
@media (max-width: 767px) {
  .nav__links {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--color-white);
    flex-direction: column;
    padding: var(--space-md) var(--space-lg);
    border-bottom: 1px solid var(--color-border);
    gap: var(--space-md);
  }

  .nav__links--open {
    display: flex;
  }

  .nav__toggle {
    display: block;
  }

  .hero { padding: var(--space-2xl) var(--space-lg); }
  .hero__title { font-size: 2.25rem; }
  .hero__subtitle { font-size: 1rem; }

  .section { padding: var(--space-2xl) var(--space-lg); }

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

  .step-indicator__line { width: 20px; }

  .selection-summary {
    flex-wrap: wrap;
    font-size: 0.8125rem;
  }

  .result-card__header { flex-direction: column; align-items: flex-start; gap: var(--space-md); }
  .result-card__match { text-align: left; }
}