/* ============================================================
   ByteForge — design tokens
   Developer / data aesthetic: deep ink surfaces, amber "on" bits,
   teal primary accent. Dark-first with full light mode.
   ============================================================ */
:root,
[data-theme='light'] {
  --font-display: 'Cabinet Grotesk', 'Inter', sans-serif;
  --font-body: 'Inter', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, monospace;

  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.8125rem, 0.78rem + 0.2vw, 0.9375rem);
  --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.6vw, 1.375rem);
  --text-xl: clamp(1.5rem, 1.25rem + 1vw, 2rem);

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;

  /* light surfaces — cool paper */
  --color-bg: #f4f6fa;
  --color-surface: #ffffff;
  --color-surface-2: #f7f9fc;
  --color-surface-offset: #eef1f6;
  --color-divider: #e2e7ef;
  --color-border: #d6dce6;
  --color-text: #0f1623;
  --color-text-muted: #5a6478;
  --color-text-faint: #9aa3b5;

  --color-primary: #0c6e8c;
  --color-primary-hover: #0a5a73;
  --color-primary-highlight: #dcf0f5;

  --color-on: #c2620f; /* amber-ish for lit bits */
  --color-on-soft: #fbe6cf;
  --color-low: #6b3fa0; /* low nibble accent (purple) */
  --color-low-soft: #ede4f6;

  --color-grid: rgba(15, 22, 35, 0.04);

  --radius-sm: 0.5rem;
  --radius-md: 0.75rem;
  --radius-lg: 1rem;
  --radius-xl: 1.25rem;

  --shadow-sm: 0 1px 2px rgba(15, 22, 35, 0.06);
  --shadow-md: 0 6px 20px rgba(15, 22, 35, 0.08);
  --shadow-lg: 0 18px 48px rgba(15, 22, 35, 0.12);
  --transition: 180ms cubic-bezier(0.16, 1, 0.3, 1);
}

[data-theme='dark'] {
  --color-bg: #0a0d14;
  --color-surface: #0f131c;
  --color-surface-2: #131826;
  --color-surface-offset: #161c2b;
  --color-divider: #1e2536;
  --color-border: #283145;
  --color-text: #e3e8f2;
  --color-text-muted: #8b95ad;
  --color-text-faint: #5a6478;

  --color-primary: #4cc4e0;
  --color-primary-hover: #6fd4e8;
  --color-primary-highlight: #123240;

  --color-on: #ffb454;
  --color-on-soft: #2a2010;
  --color-low: #b78de6;
  --color-low-soft: #221a33;

  --color-grid: rgba(255, 255, 255, 0.028);

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.45);
  --shadow-lg: 0 22px 56px rgba(0, 0, 0, 0.55);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --color-bg: #0a0d14;
    --color-surface: #0f131c;
    --color-surface-2: #131826;
    --color-surface-offset: #161c2b;
    --color-divider: #1e2536;
    --color-border: #283145;
    --color-text: #e3e8f2;
    --color-text-muted: #8b95ad;
    --color-text-faint: #5a6478;
    --color-primary: #4cc4e0;
    --color-primary-hover: #6fd4e8;
    --color-primary-highlight: #123240;
    --color-on: #ffb454;
    --color-on-soft: #2a2010;
    --color-low: #b78de6;
    --color-low-soft: #221a33;
    --color-grid: rgba(255, 255, 255, 0.028);
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
    --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.45);
    --shadow-lg: 0 22px 56px rgba(0, 0, 0, 0.55);
  }
}

/* ============================================================
   Base
   ============================================================ */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
html {
  -webkit-text-size-adjust: none;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}
body {
  min-height: 100dvh;
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  overflow-x: hidden;
}
img,
svg {
  display: block;
  max-width: 100%;
}
input,
button,
textarea,
select {
  font: inherit;
  color: inherit;
}
h1,
h2,
h3 {
  text-wrap: balance;
  line-height: 1.12;
}
p {
  text-wrap: pretty;
}
a,
button,
[role='button'],
input {
  transition: color var(--transition), background var(--transition), border-color var(--transition),
    box-shadow var(--transition), transform var(--transition);
}
button {
  cursor: pointer;
  background: none;
  border: none;
}
::selection {
  background: color-mix(in oklab, var(--color-primary) 30%, transparent);
}
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}
.sr-only,
.skip-link {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
}
.skip-link:focus {
  width: auto;
  height: auto;
  clip: auto;
  top: var(--space-3);
  left: var(--space-3);
  z-index: 50;
  padding: var(--space-2) var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
}
.kbd {
  font-family: var(--font-mono);
  font-size: 0.8em;
  padding: 0.1em 0.4em;
  border-radius: 0.35em;
  background: var(--color-surface-offset);
  border: 1px solid var(--color-border);
  color: var(--color-text);
}

/* ============================================================
   Background grid
   ============================================================ */
.grid-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  background-image: linear-gradient(var(--color-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-grid) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(ellipse 90% 70% at 50% 0%, #000 35%, transparent 100%);
  -webkit-mask-image: radial-gradient(ellipse 90% 70% at 50% 0%, #000 35%, transparent 100%);
}

/* ============================================================
   Header
   ============================================================ */
.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 920px;
  margin: 0 auto;
  padding: var(--space-6) var(--space-4) var(--space-4);
}
.brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  color: var(--color-primary);
}
.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1;
}
.brand-name {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: var(--text-lg);
  letter-spacing: -0.02em;
  color: var(--color-text);
}
.brand-sub {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.04em;
  color: var(--color-text-faint);
  text-transform: lowercase;
  margin-top: 3px;
}
.theme-toggle {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-muted);
}
.theme-toggle:hover {
  color: var(--color-text);
  border-color: var(--color-primary);
}

/* ============================================================
   Layout
   ============================================================ */
.container {
  max-width: 920px;
  margin: 0 auto;
  padding: var(--space-4) var(--space-4) var(--space-12);
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
}
.intro {
  padding: var(--space-2) var(--space-1) var(--space-2);
}
.intro h1 {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: var(--text-xl);
  letter-spacing: -0.03em;
  margin-bottom: var(--space-2);
}
.intro .lede {
  color: var(--color-text-muted);
  max-width: 60ch;
  font-size: var(--text-base);
}

.panel {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-5);
  box-shadow: var(--shadow-sm);
}
.panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin-bottom: var(--space-5);
}
.panel-head h2 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--text-lg);
  letter-spacing: -0.01em;
}
.panel-note {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

/* chips / quick actions */
.quick-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}
.chip {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  padding: 0.4rem 0.7rem;
  border-radius: var(--radius-full, 9999px);
  border: 1px solid var(--color-border);
  background: var(--color-surface-2);
  color: var(--color-text-muted);
  letter-spacing: 0.02em;
}
.chip:hover {
  color: var(--color-text);
  border-color: var(--color-primary);
  background: var(--color-primary-highlight);
}
.chip.ghost {
  background: transparent;
}

/* ============================================================
   Byte editor
   ============================================================ */
.byte-stage {
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
}
.weights {
  display: grid;
  grid-template-columns: repeat(4, 1fr) 14px repeat(4, 1fr);
  gap: var(--space-2);
  align-items: center;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}
.weights span {
  text-align: center;
}
.nibble-gap {
  width: 14px;
}
.nibbles {
  display: flex;
  align-items: stretch;
  gap: var(--space-2);
}
.nibble {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  padding: var(--space-3);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  background: var(--color-surface-2);
}
.nibble-tag {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-faint);
  text-align: center;
}
.nibble--high {
  border-color: color-mix(in oklab, var(--color-on) 40%, var(--color-border));
}
.nibble--low {
  border-color: color-mix(in oklab, var(--color-low) 40%, var(--color-border));
}
.bits {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-2);
}
.bit {
  display: block;
  cursor: pointer;
}
.bit input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}
.bit-cell {
  display: grid;
  place-items: center;
  aspect-ratio: 1;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  background: var(--color-surface-offset);
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: var(--text-lg);
  color: var(--color-text-faint);
  transition: all var(--transition);
}
.bit:hover .bit-cell {
  border-color: var(--color-text-muted);
  color: var(--color-text-muted);
}
.bit input:focus-visible + .bit-cell {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}
/* ON state — high nibble amber, low nibble purple */
.nibble--high .bit input:checked + .bit-cell {
  background: var(--color-on-soft);
  border-color: var(--color-on);
  color: var(--color-on);
  box-shadow: 0 0 0 1px var(--color-on), 0 0 18px -4px var(--color-on);
}
.nibble--low .bit input:checked + .bit-cell {
  background: var(--color-low-soft);
  border-color: var(--color-low);
  color: var(--color-low);
  box-shadow: 0 0 0 1px var(--color-low), 0 0 18px -4px var(--color-low);
}

.nibble-bridge {
  align-self: center;
  width: 2px;
  flex: 0 0 2px;
  background: var(--color-divider);
  border-radius: 2px;
  margin: var(--space-6) 0;
}

.decimal-readout {
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  border-top: 1px dashed var(--color-divider);
}
.readout-label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-faint);
}
.readout-value {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: var(--text-lg);
  color: var(--color-text);
  font-variant-numeric: tabular-nums;
}

/* ============================================================
   Result panel
   ============================================================ */
.result-stage {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
}
.hex-display {
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: clamp(2.5rem, 4vw + 1rem, 4rem);
  letter-spacing: -0.02em;
  line-height: 1;
  display: flex;
  align-items: baseline;
}
.hex-prefix {
  color: var(--color-primary);
  margin-right: 0.05em;
}
.hex-digit {
  position: relative;
  padding: 0 0.06em;
}
.hex-digit--high {
  color: var(--color-on);
}
.hex-digit--low {
  color: var(--color-low);
}
.hex-display.fmt-bare .hex-prefix,
.hex-display.fmt-bin .hex-prefix {
  display: none;
}
.hex-display.fmt-bin {
  letter-spacing: 0.04em;
}
.hex-display.fmt-bin .hex-digit {
  color: var(--color-text);
  font-weight: 700;
  font-size: 0.62em;
}

.copy-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: 0.7rem 1.2rem;
  border-radius: var(--radius-md);
  background: var(--color-primary);
  color: #04141a;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: var(--text-sm);
  box-shadow: var(--shadow-md);
}
.copy-btn:hover {
  background: var(--color-primary-hover);
  transform: translateY(-1px);
}
.copy-btn.copied {
  background: var(--color-on);
}
.copy-hint {
  margin-top: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-primary);
  min-height: 1em;
}

/* format switch */
.format-switch {
  display: inline-flex;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full, 9999px);
  padding: 3px;
  background: var(--color-surface-2);
}
.fmt {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  padding: 0.35rem 0.7rem;
  border-radius: 9999px;
  color: var(--color-text-muted);
  white-space: nowrap;
}
.fmt.active {
  background: var(--color-surface);
  color: var(--color-text);
  box-shadow: var(--shadow-sm);
}

/* ============================================================
   Nibble-split map
   ============================================================ */
.map-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-4);
}
.map-card {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  padding: var(--space-4);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  background: var(--color-surface-2);
}
.map-card--high {
  border-color: color-mix(in oklab, var(--color-on) 35%, var(--color-border));
}
.map-card--low {
  border-color: color-mix(in oklab, var(--color-low) 35%, var(--color-border));
}
.map-card-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.map-tag {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-faint);
}
.map-weight-sum {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}
.map-bits {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-2);
}
.map-bit {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: var(--space-2) 4px;
  border-radius: var(--radius-sm);
  background: var(--color-surface-offset);
  border: 1px solid var(--color-border);
}
.map-bit-val {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: var(--text-lg);
  color: var(--color-text-faint);
}
.map-bit-weight {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  color: var(--color-text-faint);
}
.map-card--high .map-bit.on .map-bit-val {
  color: var(--color-on);
}
.map-card--high .map-bit.on {
  background: var(--color-on-soft);
  border-color: var(--color-on);
}
.map-card--low .map-bit.on .map-bit-val {
  color: var(--color-low);
}
.map-card--low .map-bit.on {
  background: var(--color-low-soft);
  border-color: var(--color-low);
}
.map-arrow {
  text-align: center;
  color: var(--color-text-faint);
  font-size: var(--text-lg);
  line-height: 1;
}
.map-result {
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: var(--space-3);
}
.map-result-label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-faint);
}
.map-hex {
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: var(--text-xl);
}
.map-card--high .map-hex {
  color: var(--color-on);
}
.map-card--low .map-hex {
  color: var(--color-low);
}

/* formula button + tooltip */
.formula-wrap {
  position: relative;
}
.map-formula {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  width: 100%;
  padding: 0.5rem var(--space-3);
  border-radius: var(--radius-sm);
  border: 1px dashed var(--color-border);
  background: var(--color-surface);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-text-muted);
}
.map-formula:hover {
  color: var(--color-text);
  border-color: var(--color-primary);
}
.map-formula-text {
  font-variant-numeric: tabular-nums;
}
.info-icon {
  flex: 0 0 auto;
  color: var(--color-text-faint);
}
.tooltip {
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%) translateY(4px);
  width: max-content;
  max-width: 240px;
  padding: var(--space-3);
  border-radius: var(--radius-sm);
  background: var(--color-text);
  color: var(--color-bg);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  line-height: 1.5;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition), transform var(--transition);
  z-index: 5;
}
.tooltip strong {
  color: var(--color-on);
}
.map-card--low .tooltip strong {
  color: var(--color-low);
}
.map-formula:hover + .tooltip,
.map-formula:focus-visible + .tooltip,
.map-formula:focus + .tooltip,
.map-formula:focus-within + .tooltip {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* equation row */
.map-equation {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
  margin-top: var(--space-5);
  padding-top: var(--space-4);
  border-top: 1px dashed var(--color-divider);
  font-family: var(--font-mono);
  flex-wrap: wrap;
}
.eq-hex {
  font-weight: 800;
  font-size: var(--text-lg);
}
.map-equation .eq-hex:first-of-type {
  color: var(--color-on);
}
.map-equation .eq-hex:last-of-type {
  color: var(--color-low);
}
.eq-join {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}
.eq-eq {
  color: var(--color-text-faint);
  font-size: var(--text-lg);
}
.eq-final {
  font-weight: 800;
  font-size: var(--text-lg);
  color: var(--color-primary);
}

/* ============================================================
   Math breakdown
   ============================================================ */
.math-body {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
}
.math-body[hidden] {
  display: none;
}
.math-step {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-sm);
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
}
.math-num {
  flex: 0 0 auto;
  width: 22px;
  height: 22px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: var(--color-primary-highlight);
  color: var(--color-primary);
  font-size: var(--text-xs);
  font-weight: 700;
}
.math-content {
  flex: 1;
  line-height: 1.7;
}
.math-content .hl-high {
  color: var(--color-on);
  font-weight: 700;
}
.math-content .hl-low {
  color: var(--color-low);
  font-weight: 700;
}
.math-content .hl-pri {
  color: var(--color-primary);
  font-weight: 700;
}
.math-content code {
  font-family: var(--font-mono);
  padding: 0 0.3em;
  border-radius: 0.3em;
  background: var(--color-surface-offset);
  border: 1px solid var(--color-border);
}

/* ============================================================
   Footer
   ============================================================ */
.site-footer {
  max-width: 920px;
  margin: 0 auto;
  padding: var(--space-8) var(--space-4) var(--space-10);
  text-align: center;
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  font-family: var(--font-mono);
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 640px) {
  .map-grid {
    grid-template-columns: 1fr;
  }
  .weights {
    grid-template-columns: repeat(4, 1fr) 10px repeat(4, 1fr);
    font-size: 0.65rem;
    gap: var(--space-1);
  }
  .nibbles {
    gap: var(--space-1);
  }
  .nibble {
    padding: var(--space-2);
  }
  .bits,
  .map-bits {
    gap: var(--space-1);
  }
  .result-stage {
    justify-content: center;
    text-align: center;
  }
  .panel-head {
    flex-direction: column;
    align-items: flex-start;
  }
}
@media (max-width: 380px) {
  .bit-cell {
    font-size: var(--text-base);
  }
}

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