/* ============================================
   Gear Calculator — Swiss Grid Style
   ============================================ */

:root {
  --font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;

  /* Colors */
  --color-black: #1a1a1a;
  --color-white: #ffffff;
  --color-gray-50: #f5f4f0;
  --color-gray-100: #eceae5;
  --color-gray-200: #d9d7d2;
  --color-gray-300: #c8c7c3;
  --color-gray-500: #6b6b6b;
  --color-gray-700: #404040;

  /* Drivetrain Colors */
  --color-a: #0a0a0a;
  --color-b: #dc2626;

  /* Spacing */
  --space-1: 0.5rem;
  --space-2: 1rem;
  --space-3: 1.5rem;
  --space-4: 2rem;
  --space-5: 3rem;
  --space-6: 4rem;

  /* Layout */
  --container-max: 1200px;
  --container-padding: var(--space-4);
}

/* Dark Mode */
[data-theme="dark"] {
  --color-black: #f0efe9;
  --color-white: #1c1b18;
  --color-gray-50: #141412;
  --color-gray-100: #1c1b18;
  --color-gray-200: #2e2d29;
  --color-gray-300: #454440;
  --color-gray-500: #a3a298;
  --color-gray-700: #d4d3ce;
  --color-a: #f0efe9;
  --color-b: #f87171;
}

/* ============================================
   Reset & Base
   ============================================ */

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-family);
  font-weight: 400;
  line-height: 1.5;
  color: var(--color-black);
  background-color: var(--color-gray-50);
}

/* ============================================
   Layout
   ============================================ */

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: var(--space-4);
}

.main {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0 var(--space-5);
}

/* ============================================
   Header
   ============================================ */

.header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  padding-bottom: var(--space-3);
  border-bottom: 2px solid var(--color-black);
}

.header-left {
  flex: 1;
}

.logo {
  font-size: 2rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: -0.03em;
  line-height: 1.05;
}

.tagline {
  font-size: 0.875rem;
  color: var(--color-gray-500);
  letter-spacing: 0;
}

/* Dark Mode Toggle */
.dark-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border: none;
  background: transparent;
  color: var(--color-gray-500);
  cursor: pointer;
  transition: color 0.15s;
}

.dark-toggle:hover {
  color: var(--color-black);
}

.dark-toggle .icon-moon {
  display: none;
}

[data-theme="dark"] .dark-toggle .icon-sun {
  display: none;
}

[data-theme="dark"] .dark-toggle .icon-moon {
  display: block;
}

/* ============================================
   Drivetrain Input Sections
   ============================================ */

.drivetrain {
  padding-block: var(--space-3);
}

#drivetrain-a {
  padding-right: var(--space-5);
}

#drivetrain-b {
  padding-left: 0;
}

.drivetrain-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-3);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--color-black);
}

.drivetrain-title {
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-gray-500);
}

.color-indicator {
  width: 12px;
  height: 12px;
}

.copy-btn {
  font-family: inherit;
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-gray-500);
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
  transition: color 0.15s;
}

.copy-btn:hover {
  color: var(--color-black);
}

.input-group {
  margin-bottom: var(--space-2);
}

.input-group:last-child {
  margin-bottom: 0;
}

.input-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-2);
}

.input-row .input-group {
  margin-bottom: 0;
}

.label {
  display: block;
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-gray-500);
  margin-bottom: var(--space-1);
}

.input {
  width: 100%;
  padding: 0.5rem 0;
  font-family: inherit;
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  border: none;
  border-bottom: 1px solid var(--color-gray-300);
  background: transparent;
  color: var(--color-black);
  transition: border-color 0.15s;
  border-radius: 0;
  -webkit-appearance: none;
}

.input:focus {
  outline: none;
  border-bottom-color: var(--color-black);
}

select.input {
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  -moz-appearance: none;
  padding-right: 1.5rem;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%236b6b6b' fill='none' stroke-width='1.5'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0 center;
}

select.input option {
  font-size: 1rem;
  font-weight: 400;
}

.input-hint {
  display: block;
  font-size: 0.625rem;
  color: var(--color-gray-500);
  margin-top: 0.25rem;
}

/* Custom input - hidden by default, shown when Custom is selected */
.input-custom {
  display: none;
  margin-top: var(--space-1);
}

.input-custom.visible {
  display: block;
}

/* ============================================
   Cadence Section
   ============================================ */

.cadence-section {
  grid-column: 1 / -1;
  padding-block: var(--space-3);
  border-top: 2px solid var(--color-black);
}

.cadence-section .input-group {
  margin-bottom: 0;
}

.cadence-section .input-group:first-child {
  max-width: 140px;
}

.cadence-row {
  display: flex;
  gap: var(--space-4);
  align-items: flex-end;
}

/* Toggle */
.toggle {
  display: flex;
  align-items: center;
  border: 1.5px solid var(--color-gray-300);
  transition: border-color 0.15s;
}

.toggle:hover {
  border-color: var(--color-black);
}

.toggle-btn {
  padding: 0.375rem 0.75rem;
  font-family: inherit;
  font-size: 0.8125rem;
  font-weight: 500;
  border: none;
  background: transparent;
  color: var(--color-gray-500);
  cursor: pointer;
  transition: color 0.15s;
}

.toggle-btn:first-child {
}

.toggle-btn.active {
  color: var(--color-black);
  font-weight: 700;
}

.toggle-btn:hover:not(.active) {
  color: var(--color-black);
}

/* ============================================
   Results Section
   ============================================ */

.results {
  grid-column: 1 / -1;
  padding-block: var(--space-3) 0;
  border-top: 2px solid var(--color-black);
}

.section-title {
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-gray-500);
  margin-bottom: var(--space-3);
}

/* Chart */
.chart-container {
  margin-bottom: var(--space-3);
  padding: 0 var(--space-3);
  display: grid;
  grid-template-columns: auto 1fr;
  grid-template-rows: auto auto;
  column-gap: var(--space-1);
}

.chart-container .chart {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: subgrid;
  row-gap: 4px;
}

.chart-container .chart-label {
  grid-row: 2;
  grid-column: 1;
}

.chart-container .chart-axis {
  grid-row: 2;
  grid-column: 2;
}

.chart {
  margin-bottom: var(--space-1);
}

.chart-row {
  display: contents;
}

.chart-row-label {
  font-size: 0.5625rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-gray-500);
  align-self: center;
  text-align: right;
  white-space: nowrap;
  height: 14px;
  display: flex;
  align-items: center;
  justify-content: flex-end;
}

.chart-row-bars {
  position: relative;
  height: 8px;
  align-self: center;
}

.chart-gap {
  grid-column: 1 / -1;
  height: 6px;
}

.chart-bar {
  position: absolute;
  height: 8px;
  min-width: 2px;
  top: 0;
  transition: all 0.2s ease;
}

.chart-bar.set-a {
  background: var(--color-a);
}

.chart-bar.set-b {
  background: var(--color-b);
}

.chart-bar:hover {
  height: 12px;
  top: -2px;
}

.chart-axis {
  display: flex;
  justify-content: space-between;
  align-self: center;
  font-size: 0.625rem;
  color: var(--color-gray-500);
  font-variant-numeric: tabular-nums;
}

.chart-label {
  text-align: right;
  font-size: 0.625rem;
  font-weight: 400;
  color: var(--color-gray-500);
  align-self: center;
  white-space: nowrap;
  font-style: italic;
}

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr var(--space-5) 1fr 1fr 1fr;
  gap: 0;
  border-top: 1px solid var(--color-gray-300);
  border-bottom: 1px solid var(--color-gray-300);
}

/* Desktop: place A,B,A,B,A,B into columns A,A,A, gap, B,B,B */
.stat-card[data-stat="range-a"] { grid-column: 1; grid-row: 1; }
.stat-card[data-stat="low-a"]   { grid-column: 2; grid-row: 1; }
.stat-card[data-stat="high-a"]  { grid-column: 3; grid-row: 1; }
.stat-card[data-stat="range-b"] { grid-column: 5; grid-row: 1; }
.stat-card[data-stat="low-b"]   { grid-column: 6; grid-row: 1; }
.stat-card[data-stat="high-b"]  { grid-column: 7; grid-row: 1; }

.stat-card {
  padding: var(--space-2) var(--space-1);
}

.stat-card[data-stat="range-a"],
.stat-card[data-stat="range-b"] {
  padding-left: 0;
}

.stat-label {
  font-size: 0.625rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-gray-500);
  margin-bottom: 0.375rem;
}

.stat-value {
  font-size: 1.25rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
  line-height: 1;
}

.stat-unit {
  font-size: 0.625rem;
  color: var(--color-gray-500);
  margin-top: 0.25rem;
}

/* ============================================
   Tables Section
   ============================================ */

.tables {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0 var(--space-5);
  border-top: 2px solid var(--color-black);
  padding-top: var(--space-3);
}

.table-wrap {
  overflow: hidden;
}

.table-wrap:first-child {
  padding-right: var(--space-5);
}

.table-title {
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-gray-500);
  margin-bottom: var(--space-2);
  padding-bottom: var(--space-1);
  border-bottom: 1px solid var(--color-black);
}

.table-scroll {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.table {
  width: 100%;
  border-collapse: collapse;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.table th,
.table td {
  padding: 0.5rem 0.5rem;
  text-align: right;
  border-bottom: 1px solid var(--color-gray-200);
}

.table td {
  font-size: 0.9375rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--color-black);
}

.table th {
  font-weight: 700;
  font-size: 0.625rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-gray-500);
  background: var(--color-gray-50);
  position: sticky;
  top: 0;
}

.table th:first-child,
.table td:first-child {
  text-align: left;
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-gray-500);
  position: sticky;
  left: 0;
  padding-left: 0;
  background: var(--color-gray-50);
}

.table th:first-child {
  z-index: 1;
}

.table tr:hover td {
  background: var(--color-gray-100);
}

.table tr:hover td:first-child {
  background: var(--color-gray-200);
}

.table .speed {
  font-size: 0.625rem;
  font-weight: 400;
  letter-spacing: 0;
  color: var(--color-gray-500);
  display: block;
  margin-top: 0.125rem;
}

/* ============================================
   Footer
   ============================================ */

.footer {
  margin-top: var(--space-4);
  padding-top: var(--space-3);
  border-top: 2px solid var(--color-black);
  font-size: 0.6875rem;
  color: var(--color-gray-500);
}

.footer p {
  margin-bottom: 0.25rem;
}

/* ============================================
   Responsive — Tablet
   ============================================ */

@media (max-width: 900px) {
  .main {
    grid-template-columns: 1fr;
  }

  #drivetrain-a {
    border-right: none;
    padding-right: 0;
    border-bottom: 2px solid var(--color-black);
    padding-bottom: var(--space-3);
  }

  #drivetrain-b {
    padding-top: var(--space-3);
  }

  .tables {
    grid-template-columns: 1fr;
    gap: var(--space-4) 0;
  }

  .table-wrap:first-child {
    border-right: none;
    padding-right: 0;
    border-bottom: 2px solid var(--color-black);
    padding-bottom: var(--space-3);
  }

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

  .stat-card[data-stat] {
    grid-column: unset;
    grid-row: unset;
  }

  .stat-card {
    padding: var(--space-2) var(--space-1);
  }

  .stat-card[data-stat="range-a"],
  .stat-card[data-stat="range-b"] {
    padding-left: var(--space-1);
  }

  .stat-card:nth-child(-n+4) {
    border-bottom: 1px solid var(--color-gray-300);
    padding-bottom: var(--space-2);
    margin-bottom: var(--space-2);
  }

  .stat-card:first-child {
    padding-left: 0;
  }
}

/* ============================================
   Responsive — Mobile
   ============================================ */

@media (max-width: 600px) {
  :root {
    --container-padding: var(--space-2);
  }

  .header {
    margin-bottom: var(--space-3);
    padding-bottom: var(--space-2);
  }

  .logo {
    font-size: 1.5rem;
  }

  .tagline {
    font-size: 0.75rem;
  }

  .main {
    gap: var(--space-2);
  }

  .input-row {
    grid-template-columns: 1fr;
    gap: var(--space-2);
  }

  .input-row .input-group {
    margin-bottom: 0;
  }

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

  .stat-card {
    padding: var(--space-1) var(--space-1);
  }

  .stat-card:first-child {
    padding-left: 0;
  }

  .stat-card:nth-child(-n+4) {
    border-bottom: 1px solid var(--color-gray-300);
    padding-bottom: var(--space-1);
    margin-bottom: var(--space-1);
  }

  .stat-value {
    font-size: 1rem;
  }

  .table th,
  .table td {
    padding: 0.375rem 0.25rem;
  }

  .table td {
    font-size: 0.8125rem;
  }

  .table .speed {
    font-size: 0.5625rem;
  }

  .footer {
    font-size: 0.625rem;
  }
}