/* ============================================
   AMZKIT RATING CALCULATOR — STYLES
   Adopts the Amzkit design system: white/light
   background, primary blue #165DFF, Inter font
   ============================================ */

:root {
  --color-primary: #165DFF;
  --color-primary-hover: #0E42D2;
  --color-primary-light: #EBF0FF;
  --color-white: #FFFFFF;
  --color-surface: #F5F7FA;
  --color-border: #E8ECF0;
  --color-text: #1A202C;
  --color-text-secondary: #5C6B7A;
  --color-text-muted: #9AA6AF;
  --color-star: #F59E0B;
  --color-star-bg: #FFF8E7;
  --color-success: #16A34A;
  --color-warning: #D97706;
  --color-danger: #DC2626;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 12px;

  --shadow-card: 0 2px 12px rgba(22, 93, 255, 0.06);
  --shadow-card-hover: 0 8px 32px rgba(22, 93, 255, 0.12);
  --shadow-nav: 0 1px 0 var(--color-border);

  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'PingFang SC', sans-serif;
  --nav-height: 64px;
  --section-py: 56px;
  --container-max: 1200px;
  --container-px: 24px;
  --transition: 150ms ease;
}

/* ============================================
   RESET & BASE
   ============================================ */

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font);
  color: var(--color-text);
  background: var(--color-white);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img, svg { display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: 3px;
}

::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--color-border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--color-text-muted); }

::selection { background: var(--color-primary-light); color: var(--color-primary); }

/* ============================================
   LAYOUT
   ============================================ */

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-px);
}

/* ============================================
   NAVIGATION (brand-consistent with homepage)
   ============================================ */

.site-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-px);
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 9px;
  flex-shrink: 0;
}

.logo-img {
  height: 64px;
  width: auto;
  flex-shrink: 0;
}

.logo-text {
  display: none;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-link {
  font-size: 15px;
  font-weight: 500;
  color: var(--color-text-secondary);
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  transition: color var(--transition), background var(--transition);
}

.nav-link:hover {
  color: var(--color-primary);
  background: var(--color-primary-light);
}

.nav-cta { margin-left: 8px; }

/* ============================================
   BUTTONS
   ============================================ */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  font-family: var(--font);
  font-size: 15px;
  font-weight: 600;
  line-height: 1;
  padding: 12px 28px;
  border-radius: var(--radius-sm);
  border: 1.5px solid transparent;
  cursor: pointer;
  transition: background var(--transition), border-color var(--transition),
              color var(--transition), box-shadow var(--transition),
              transform 80ms ease;
  white-space: nowrap;
}

.btn:active { transform: scale(0.98); }

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

.btn-ghost { background: transparent; color: var(--color-primary); border-color: var(--color-primary); }
.btn-ghost:hover { background: var(--color-primary-light); }

.btn-sm { font-size: 13px; padding: 8px 18px; }

/* ============================================
   HAMBURGER MENU (mobile)
   ============================================ */

.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 36px;
  height: 36px;
  padding: 6px;
  border-radius: var(--radius-sm);
  transition: background var(--transition);
}

.hamburger:hover { background: var(--color-surface); }

.hamburger-line {
  display: block;
  width: 20px;
  height: 1.5px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform 250ms ease, opacity 250ms ease;
  transform-origin: center;
}

.hamburger.is-active .hamburger-line:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.hamburger.is-active .hamburger-line:nth-child(2) { opacity: 0; transform: scaleX(0); }
.hamburger.is-active .hamburger-line:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* ============================================
   PAGE HEADER
   ============================================ */

.page-header {
  padding-top: calc(var(--nav-height) + 48px);
  padding-bottom: 40px;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-white);
}

.page-breadcrumb {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 16px;
}

.breadcrumb-link {
  font-size: 13px;
  color: var(--color-text-muted);
  transition: color var(--transition);
}

.breadcrumb-link:hover { color: var(--color-primary); }

.breadcrumb-sep {
  font-size: 13px;
  color: var(--color-border);
}

.breadcrumb-current {
  font-size: 13px;
  color: var(--color-text-secondary);
}

.page-title {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: clamp(24px, 3.5vw, 32px);
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.6px;
  margin-bottom: 10px;
  line-height: 1.2;
}

.page-sub {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* ============================================
   CALCULATOR MAIN LAYOUT
   ============================================ */

.calculator-main {
  padding: 48px 0 80px;
  background: var(--color-surface);
  min-height: calc(100vh - var(--nav-height));
}

/* ============================================
   TABS
   ============================================ */

.calc-tabs {
  display: flex;
  gap: 10px;
  margin-bottom: 28px;
  flex-wrap: wrap;
}

.calc-tab {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text-secondary);
  background: var(--color-white);
  border: 1.5px solid var(--color-border);
  padding: 10px 20px;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: color var(--transition), border-color var(--transition),
              background var(--transition), box-shadow var(--transition);
}

.calc-tab i { font-size: 15px; }

.calc-tab:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-light);
}

.calc-tab.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-white);
  box-shadow: var(--shadow-card);
}

.calc-tab.active:hover {
  background: var(--color-primary-hover);
  border-color: var(--color-primary-hover);
}

/* ============================================
   CALC PANELS
   ============================================ */

.calc-panel { display: none; }
.calc-panel.active { display: block; }

/* ============================================
   CALC LAYOUT (2-column grid)
   ============================================ */

.calc-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: start;
}

.calc-form, .calc-results {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 28px;
}

.calc-section-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 17px;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 20px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--color-border);
}

.calc-section-title i {
  color: var(--color-primary);
  font-size: 15px;
}

/* ============================================
   HINT
   ============================================ */

.calc-hint {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--color-text-secondary);
  background: var(--color-primary-light);
  border-left: 3px solid var(--color-primary);
  padding: 8px 14px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin-bottom: 20px;
}

.calc-hint i { color: var(--color-primary); font-size: 13px; }

/* ============================================
   FORM FIELDS
   ============================================ */

.calc-group {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 16px;
  margin-bottom: 20px;
}

.calc-group-title {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: 14px;
}

.calc-group-title i { font-size: 13px; color: var(--color-text-muted); }

.field { margin-bottom: 16px; }

.field-label {
  display: block;
  font-size: 13px;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 6px;
  line-height: 1.4;
}

.field-hint {
  color: var(--color-text-muted);
  font-size: 12px;
  font-weight: 400;
  margin-left: 6px;
}

.input-wrap {
  position: relative;
  display: flex;
  align-items: center;
}

.field-input {
  width: 100%;
  padding: 10px 38px 10px 14px;
  background: var(--color-white);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text);
  font-size: 15px;
  font-family: var(--font);
  transition: border-color var(--transition), box-shadow var(--transition);
  -webkit-appearance: none;
}

.field-input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(22, 93, 255, 0.1);
}

.field-input:hover:not(:focus) { border-color: var(--color-text-muted); }

.input-icon {
  position: absolute;
  right: 12px;
  color: var(--color-text-muted);
  font-size: 14px;
  pointer-events: none;
}

.input-suffix {
  position: absolute;
  right: 12px;
  color: var(--color-text-muted);
  font-size: 13px;
  pointer-events: none;
}

.field-input.compact {
  padding-right: 30px;
}

.field-error {
  color: var(--color-danger);
  font-size: 12px;
  margin-top: 5px;
  min-height: 16px;
  display: none;
}

/* ============================================
   STAR DISTRIBUTION
   ============================================ */

.star-distribution { margin-top: 10px; }

.star-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
  margin-top: 8px;
}

.star-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.star-label {
  font-size: 13px;
  color: var(--color-text-secondary);
  min-width: 40px;
  display: flex;
  align-items: center;
  gap: 4px;
}

.star-label i {
  font-size: 11px;
  color: var(--color-star);
}

.star-row .input-wrap { flex: 1; }

.rating-preview {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 10px;
  padding: 8px 12px;
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
}

.rating-preview-label {
  font-size: 13px;
  color: var(--color-text-muted);
}

.rating-preview-value {
  font-size: 20px;
  font-weight: 700;
  color: var(--color-star);
}

/* ============================================
   STAR PICKER
   ============================================ */

.star-picker {
  display: flex;
  gap: 8px;
  margin-top: 8px;
}

.star-btn {
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 22px;
  cursor: pointer;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  transition: color var(--transition), border-color var(--transition),
              background var(--transition), transform 80ms ease;
  line-height: 1;
}

.star-btn i { display: block; }

.star-btn:hover {
  color: var(--color-star);
  border-color: var(--color-star);
  background: var(--color-star-bg);
  transform: scale(1.1);
}

.star-btn.active {
  color: var(--color-star);
  border-color: var(--color-star);
  background: var(--color-star-bg);
}

.star-btn:active { transform: scale(0.97); }

.star-picked {
  margin-top: 8px;
  font-size: 13px;
  color: var(--color-text-muted);
}

.star-picked strong { color: var(--color-star); font-size: 15px; }

/* ============================================
   ADVANCED SECTION
   ============================================ */

.calc-advanced-toggle {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 500;
  color: var(--color-primary);
  background: none;
  border: 1px solid var(--color-border);
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  width: 100%;
  justify-content: center;
  transition: background var(--transition), border-color var(--transition);
  margin: 4px 0 20px;
  font-family: var(--font);
}

.calc-advanced-toggle i { transition: transform 250ms ease; font-size: 12px; }
.calc-advanced-toggle.expanded i { transform: rotate(180deg); }
.calc-advanced-toggle:hover { background: var(--color-primary-light); border-color: var(--color-primary); }

.calc-advanced {
  max-height: 0;
  overflow: hidden;
  transition: max-height 400ms ease;
}

.calc-advanced.show { max-height: 800px; }

.calc-advanced-group {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 16px;
  margin-bottom: 12px;
}

.calc-advanced-title {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 6px;
}

.calc-advanced-title i { font-size: 13px; color: var(--color-primary); }

.calc-advanced-hint {
  font-size: 12px;
  color: var(--color-text-muted);
  margin-bottom: 12px;
}

.slider-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.slider-label {
  min-width: 80px;
  font-size: 13px;
  color: var(--color-text-secondary);
  display: flex;
  align-items: center;
  gap: 4px;
}

.slider-label i { font-size: 11px; color: var(--color-star); }

.range-slider {
  flex: 1;
  -webkit-appearance: none;
  appearance: none;
  height: 5px;
  background: var(--color-border);
  border-radius: 3px;
  outline: none;
  cursor: pointer;
}

.range-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  background: var(--color-primary);
  border-radius: 50%;
  cursor: pointer;
  transition: transform var(--transition);
}

.range-slider::-webkit-slider-thumb:hover { transform: scale(1.2); }
.range-slider::-moz-range-thumb {
  width: 16px; height: 16px;
  background: var(--color-primary);
  border-radius: 50%;
  border: none;
  cursor: pointer;
}

.range-val {
  min-width: 40px;
  text-align: right;
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text);
}

.mixed-result {
  display: flex;
  align-items: center;
  gap: 10px;
  padding-top: 10px;
  border-top: 1px solid var(--color-border);
  margin-top: 6px;
}

.mixed-label { font-size: 13px; color: var(--color-text-secondary); }
.mixed-value { font-size: 18px; font-weight: 700; color: var(--color-star); }

.mixed-stars {
  display: flex;
  gap: 2px;
  color: var(--color-star);
  font-size: 13px;
}

/* ============================================
   SUBMIT BUTTON
   ============================================ */

.calc-submit-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 14px;
  background: var(--color-primary);
  color: var(--color-white);
  border: none;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 600;
  font-family: var(--font);
  cursor: pointer;
  transition: background var(--transition), box-shadow var(--transition), transform 80ms ease;
  box-shadow: 0 2px 8px rgba(22, 93, 255, 0.25);
  margin-top: 4px;
}

.calc-submit-btn:hover {
  background: var(--color-primary-hover);
  box-shadow: 0 4px 16px rgba(22, 93, 255, 0.3);
}

.calc-submit-btn:active { transform: scale(0.98); }

/* ============================================
   RESULTS
   ============================================ */

.results-box {
  background: var(--color-surface);
  border-radius: var(--radius-md);
  padding: 16px;
  margin-bottom: 16px;
}

.result-row {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px;
  background: var(--color-white);
  border-radius: var(--radius-sm);
  margin-bottom: 10px;
  border: 1px solid var(--color-border);
  transition: border-color var(--transition);
}

.result-row:last-child { margin-bottom: 0; }
.result-row:hover { border-color: var(--color-primary); }

.result-icon {
  width: 38px;
  height: 38px;
  background: var(--color-primary-light);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary);
  font-size: 16px;
  flex-shrink: 0;
}

.result-info { flex: 1; }

.result-label {
  font-size: 12px;
  color: var(--color-text-muted);
  margin-bottom: 3px;
  line-height: 1.3;
}

.result-val {
  font-size: 22px;
  font-weight: 700;
  color: var(--color-success);
  line-height: 1;
}

.result-val.highlight { color: var(--color-star); font-size: 26px; }

.result-val.small {
  font-size: 13px;
  font-weight: 500;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

/* ============================================
   PROGRESS BLOCK
   ============================================ */

.progress-block {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 16px;
  margin-bottom: 16px;
}

.progress-track {
  background: var(--color-border);
  border-radius: 6px;
  height: 26px;
  overflow: hidden;
  margin: 12px 0 8px;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary) 0%, #5ca3ff 100%);
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: width 600ms ease;
  min-width: 40px;
}

.progress-text {
  color: white;
  font-size: 11px;
  font-weight: 700;
  white-space: nowrap;
}

.progress-meta {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  color: var(--color-text-muted);
}

.progress-meta strong { color: var(--color-text); }

/* ============================================
   WARNING BOX
   ============================================ */

.calc-warning {
  background: #FFF8E7;
  border-left: 4px solid var(--color-warning);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 14px 16px;
  margin-top: 16px;
}

.warning-heading {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-warning);
  margin-bottom: 8px;
}

.calc-warning p {
  font-size: 13px;
  color: var(--color-text-secondary);
  line-height: 1.65;
  margin-bottom: 6px;
}

.calc-warning p:last-child { margin-bottom: 0; }

.calc-warning strong { color: var(--color-text); font-weight: 600; }

.warning-highlight { color: var(--color-danger) !important; font-weight: 600 !important; }

/* ============================================
   PRODUCT MERGE
   ============================================ */

.merge-wrap { max-width: 900px; margin: 0 auto; }

.merge-header { margin-bottom: 28px; }

.product-card {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-bottom: 16px;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.product-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-card-hover);
}

.product-card-head {
  margin-bottom: 20px;
  padding-bottom: 14px;
  border-bottom: 2px solid var(--color-border);
}

.product-card-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 16px;
  font-weight: 600;
  color: var(--color-primary);
}

.product-card-title i { font-size: 15px; color: var(--color-text-muted); }

.star-grid-merge {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px;
  margin-top: 10px;
}

.star-grid-merge .star-row {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.star-grid-merge .field-input { padding-right: 30px; }

.merge-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin: 24px 0;
}

.calc-btn {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 14px;
  font-weight: 600;
  font-family: var(--font);
  padding: 11px 20px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  border: 1.5px solid transparent;
  transition: background var(--transition), border-color var(--transition),
              color var(--transition), transform 80ms ease;
}

.calc-btn:active { transform: scale(0.98); }

.calc-btn-add {
  background: var(--color-primary);
  color: var(--color-white);
  border-color: var(--color-primary);
}

.calc-btn-add:hover {
  background: var(--color-primary-hover);
  border-color: var(--color-primary-hover);
}

.calc-btn-primary {
  background: var(--color-success);
  color: var(--color-white);
  border-color: var(--color-success);
}

.calc-btn-primary:hover {
  background: #15803d;
  border-color: #15803d;
}

.calc-btn-ghost {
  background: var(--color-surface);
  color: var(--color-text-secondary);
  border-color: var(--color-border);
}

.calc-btn-ghost:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-light);
}

/* ============================================
   MERGE RESULT
   ============================================ */

.merge-result {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px;
}

.merge-highlight {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px;
  background: var(--color-star-bg);
  border: 2px solid rgba(245, 158, 11, 0.25);
  border-radius: var(--radius-md);
  margin-bottom: 20px;
}

.merge-highlight .result-icon {
  background: rgba(245, 158, 11, 0.15);
  color: var(--color-star);
  width: 48px;
  height: 48px;
  font-size: 20px;
}

.merge-highlight .result-val { font-size: 30px; color: var(--color-star); }

.merge-table-wrap {
  overflow-x: auto;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}

.merge-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--color-surface);
}

.merge-table thead { background: var(--color-white); }

.merge-table th,
.merge-table td {
  padding: 11px 16px;
  text-align: center;
  border-bottom: 1px solid var(--color-border);
  font-size: 14px;
}

.merge-table th {
  color: var(--color-primary);
  font-weight: 600;
  font-size: 13px;
}

.merge-table td { color: var(--color-text-secondary); }

.merge-table tbody tr:hover { background: var(--color-white); }
.merge-table tbody tr:last-child td { border-bottom: none; }

/* ============================================
   FOOTER
   ============================================ */

.site-footer {
  background: var(--color-surface);
  padding: 40px 0;
  border-top: 1px solid var(--color-border);
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  text-align: center;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
}

.footer-logo .logo-text { font-size: 18px; }

.footer-tagline { font-size: 13px; color: var(--color-text-muted); }

.footer-links {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
}

.footer-link {
  font-size: 13px;
  color: var(--color-text-muted);
  transition: color var(--transition);
}

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

.footer-sep { color: var(--color-border); font-size: 13px; }

.footer-copy { font-size: 13px; color: var(--color-text-muted); }

/* ============================================
   RESPONSIVE — DESKTOP (≥1024px)
   ============================================ */

@media (min-width: 1024px) {
  :root {
    --container-px: 40px;
  }
}

/* ============================================
   RESPONSIVE — MOBILE (<768px)
   ============================================ */

@media (max-width: 767px) {
  :root {
    --section-py: 48px;
  }

  /* Nav */
  .nav-links {
    position: fixed;
    top: var(--nav-height);
    left: 0; right: 0; bottom: 0;
    background: var(--color-white);
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 4px;
    padding: 16px var(--container-px) 40px;
    border-top: 1px solid var(--color-border);
    transform: translateX(100%);
    transition: transform 250ms ease;
    overflow-y: auto;
  }

  .nav-links.is-open { transform: translateX(0); }

  .nav-link {
    font-size: 16px;
    padding: 12px 16px;
    border-radius: var(--radius-sm);
  }

  .nav-cta {
    margin-left: 0;
    margin-top: 8px;
    text-align: center;
  }

  .hamburger { display: flex; }

  /* Page header */
  .page-header {
    padding-top: calc(var(--nav-height) + 32px);
    padding-bottom: 32px;
  }

  /* Calculator */
  .calculator-main { padding: 32px 0 60px; }

  .calc-layout { grid-template-columns: 1fr; }

  .calc-form, .calc-results { padding: 20px; }

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

  .star-picker { justify-content: space-between; }

  .star-btn { font-size: 20px; padding: 7px 10px; }

  .result-val { font-size: 20px; }
  .result-val.highlight { font-size: 24px; }

  /* Merge */
  .merge-actions { flex-direction: column; }
  .calc-btn { width: 100%; justify-content: center; }

  .star-grid-merge { grid-template-columns: 1fr 1fr; }

  .merge-highlight .result-val { font-size: 26px; }

  /* Tabs */
  .calc-tabs { flex-direction: column; }
  .calc-tab { width: 100%; justify-content: center; }
}