src/styles.css

/*
 * The Return Path — Cage & Key
 * A self-contained visual system for an editorial feedback laboratory.
 */

@layer reset, tokens, base, layout, components, states, accessibility;

@layer reset {
  *,
  *::before,
  *::after {
    box-sizing: border-box;
  }

  html {
    color-scheme: dark;
    font-synthesis: none;
    text-size-adjust: 100%;
  }

  body,
  h1,
  h2,
  h3,
  p,
  ol,
  ul,
  dl,
  dd,
  figure,
  blockquote {
    margin: 0;
  }

  ol,
  ul {
    padding: 0;
  }

  button,
  input,
  select,
  textarea {
    color: inherit;
    font: inherit;
  }

  button,
  label,
  select,
  input[type="range"] {
    -webkit-tap-highlight-color: transparent;
  }

  img,
  svg {
    display: block;
    max-width: 100%;
  }
}

@layer tokens {
  :root {
    --ink-0: #070908;
    --ink-1: #0c0f0d;
    --ink-2: #111512;
    --ink-3: #171c18;
    --ink-4: #202620;
    --line: #303830;
    --line-soft: rgb(210 220 198 / 12%);
    --paper: #f1f1e7;
    --paper-soft: #c9ccbd;
    --paper-muted: #92998b;
    --key: #c8ff62;
    --key-soft: #a0ca55;
    --key-fade: rgb(200 255 98 / 12%);
    --cage: #ff785a;
    --cage-soft: #d65f49;
    --cage-fade: rgb(255 120 90 / 12%);
    --signal: #78bfff;
    --signal-soft: #6399c8;
    --signal-fade: rgb(120 191 255 / 12%);
    --gold: #e4bb66;
    --shadow: 0 24px 80px rgb(0 0 0 / 34%);
    --shadow-soft: 0 12px 32px rgb(0 0 0 / 22%);
    --sans: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    --serif: Iowan Old Style, Baskerville, "Times New Roman", Times, serif;
    --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
    --radius-xs: 0.3rem;
    --radius-sm: 0.55rem;
    --radius-md: 0.85rem;
    --radius-lg: 1.2rem;
    --content: 90rem;
    --gutter: clamp(1rem, 3vw, 3rem);
    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  }
}

@layer base {
  html {
    min-width: 20rem;
    min-height: 100%;
    background: var(--ink-0);
    scroll-behavior: smooth;
  }

  body {
    min-width: 20rem;
    min-height: 100vh;
    color: var(--paper);
    background:
      radial-gradient(circle at 78% -10%, rgb(200 255 98 / 8%), transparent 31rem),
      radial-gradient(circle at -10% 28%, rgb(120 191 255 / 6%), transparent 27rem),
      linear-gradient(180deg, var(--ink-1) 0%, var(--ink-0) 72%);
    font-family: var(--sans);
    font-size: 1rem;
    line-height: 1.55;
    text-rendering: optimizeLegibility;
  }

  body::before {
    position: fixed;
    z-index: -1;
    inset: 0;
    background-image:
      linear-gradient(var(--line-soft) 1px, transparent 1px),
      linear-gradient(90deg, var(--line-soft) 1px, transparent 1px);
    background-size: 4rem 4rem;
    content: "";
    mask-image: linear-gradient(to bottom, black, transparent 82%);
    pointer-events: none;
  }

  ::selection {
    color: var(--ink-0);
    background: var(--key);
  }

  a {
    color: var(--key);
    text-decoration-color: rgb(200 255 98 / 45%);
    text-underline-offset: 0.22em;
  }

  a:hover {
    text-decoration-color: currentColor;
  }

  button {
    border: 0;
  }
}

@layer layout {
  #root,
  #app {
    min-height: 100vh;
  }

  .app-shell {
    position: relative;
    isolation: isolate;
    width: min(100%, var(--content));
    min-height: 100vh;
    margin-inline: auto;
    padding: 1.15rem var(--gutter) 2.5rem;
  }

  .app-shell::before {
    position: absolute;
    z-index: -1;
    top: 0;
    bottom: 0;
    left: var(--gutter);
    width: 1px;
    background: linear-gradient(var(--key), var(--line) 7rem, transparent 88%);
    content: "";
    opacity: 0.42;
  }

  .masthead {
    display: grid;
    grid-template-columns: minmax(0, 1.4fr) minmax(17rem, 0.6fr);
    gap: clamp(1.5rem, 5vw, 5rem);
    align-items: end;
    padding: clamp(3.25rem, 8vw, 7.25rem) 0 clamp(2rem, 4vw, 3.4rem) clamp(0.85rem, 2vw, 1.5rem);
    border-bottom: 1px solid var(--line);
  }

  .masthead-copy {
    min-width: 0;
  }

  .main-grid {
    display: grid;
    grid-template-columns: repeat(12, minmax(0, 1fr));
    gap: clamp(0.8rem, 1.5vw, 1.25rem);
    margin-top: clamp(1.2rem, 3vw, 2.2rem);
  }

  .main-grid > .panel {
    grid-column: span 6;
  }

  .main-grid > .panel--wide,
  .main-grid > .span-8 {
    grid-column: span 8;
  }

  .main-grid > .panel--narrow,
  .main-grid > .span-4 {
    grid-column: span 4;
  }

  .main-grid > .panel--full,
  .main-grid > .span-full {
    grid-column: 1 / -1;
  }

  .control-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
  }

  .candidate-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.75rem;
  }

  .lane-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 0.75rem;
  }

  .metric-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 0.65rem;
  }
}

@layer components {
  .eyebrow {
    display: flex;
    gap: 0.7rem;
    align-items: center;
    margin-bottom: clamp(1rem, 2vw, 1.75rem);
    color: var(--key);
    font-family: var(--mono);
    font-size: 0.68rem;
    font-weight: 700;
    letter-spacing: 0.17em;
    line-height: 1.3;
    text-transform: uppercase;
  }

  .eyebrow::before {
    width: 1.55rem;
    height: 1px;
    background: currentColor;
    content: "";
  }

  .title {
    max-width: 12ch;
    color: var(--paper);
    font-family: var(--serif);
    font-size: clamp(3.15rem, 8vw, 7.4rem);
    font-weight: 400;
    letter-spacing: -0.058em;
    line-height: 0.84;
    text-wrap: balance;
  }

  .title::after {
    color: var(--key);
    content: ".";
  }

  .subtitle {
    max-width: 36rem;
    margin-top: 1.35rem;
    color: var(--paper-soft);
    font-family: var(--serif);
    font-size: clamp(1.1rem, 1.8vw, 1.42rem);
    font-style: italic;
    line-height: 1.45;
  }

  .boundary-note {
    position: relative;
    padding: 2.15rem 1.1rem 1.1rem;
    border: 1px solid var(--line);
    border-left-color: var(--signal);
    border-radius: var(--radius-sm);
    color: var(--paper-soft);
    background: linear-gradient(135deg, var(--signal-fade), transparent 62%);
    font-size: 0.83rem;
    line-height: 1.6;
  }

  .boundary-note::before {
    position: absolute;
    top: 0.75rem;
    left: 1.1rem;
    color: var(--signal);
    content: "OBSERVATION BOUNDARY";
    font-family: var(--mono);
    font-size: 0.58rem;
    font-weight: 700;
    letter-spacing: 0.14em;
  }

  .boundary-note code {
    overflow-wrap: anywhere;
    word-break: break-word;
  }

  .stage-nav {
    display: grid;
    grid-template-columns: repeat(6, minmax(0, 1fr));
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--line);
    overflow-x: auto;
    scrollbar-color: var(--line) transparent;
  }

  .stage-button {
    position: relative;
    display: flex;
    min-width: 8rem;
    min-height: 3.4rem;
    gap: 0.7rem;
    align-items: center;
    justify-content: flex-start;
    padding: 0.65rem 0.85rem;
    border-right: 1px solid var(--line-soft);
    border-radius: var(--radius-xs);
    color: var(--paper-muted);
    background: transparent;
    cursor: pointer;
    font-family: var(--mono);
    font-size: 0.68rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    line-height: 1.25;
    text-align: left;
    text-transform: uppercase;
    transition:
      color 180ms ease,
      background-color 180ms ease,
      transform 180ms var(--ease-out);
  }

  .stage-button:last-child {
    border-right-color: transparent;
  }

  .stage-button::before {
    display: grid;
    flex: 0 0 auto;
    width: 1.75rem;
    height: 1.75rem;
    place-items: center;
    border: 1px solid var(--line);
    border-radius: 50%;
    color: var(--paper-muted);
    content: attr(data-stage);
    font-size: 0.61rem;
    transition: inherit;
  }

  .stage-button:hover {
    color: var(--paper);
    background: rgb(255 255 255 / 3%);
  }

  .stage-button.is-active,
  .stage-button[aria-selected="true"],
  .stage-button[aria-current="step"] {
    color: var(--key);
    background: var(--key-fade);
  }

  .stage-button.is-active::before,
  .stage-button[aria-selected="true"]::before,
  .stage-button[aria-current="step"]::before {
    border-color: var(--key);
    color: var(--ink-0);
    background: var(--key);
    box-shadow: 0 0 1.5rem rgb(200 255 98 / 18%);
  }

  .panel {
    position: relative;
    min-width: 0;
    padding: clamp(1rem, 2vw, 1.5rem);
    border: 1px solid var(--line);
    border-radius: var(--radius-md);
    background:
      linear-gradient(145deg, rgb(255 255 255 / 2.6%), transparent 40%),
      var(--ink-2);
    box-shadow: var(--shadow-soft);
    overflow: hidden;
    animation: panel-in 560ms var(--ease-out) both;
  }

  .panel:nth-child(2) {
    animation-delay: 70ms;
  }

  .panel:nth-child(3) {
    animation-delay: 140ms;
  }

  .panel:nth-child(4) {
    animation-delay: 210ms;
  }

  .panel::after {
    position: absolute;
    top: -2.5rem;
    right: -2.5rem;
    width: 7rem;
    height: 7rem;
    border: 1px solid rgb(200 255 98 / 8%);
    border-radius: 50%;
    content: "";
    pointer-events: none;
  }

  .panel-header {
    position: relative;
    z-index: 1;
    display: flex;
    gap: 1rem;
    align-items: flex-start;
    justify-content: space-between;
    margin: calc(clamp(1rem, 2vw, 1.5rem) * -1);
    margin-bottom: 1.15rem;
    padding: 0.85rem clamp(1rem, 2vw, 1.5rem);
    border-bottom: 1px solid var(--line);
    background: rgb(0 0 0 / 14%);
  }

  .panel-title {
    color: var(--paper);
    font-family: var(--serif);
    font-size: 1.12rem;
    font-weight: 500;
    letter-spacing: -0.01em;
    line-height: 1.25;
  }

  .panel-copy,
  .helper-text {
    max-width: 65ch;
    color: var(--paper-muted);
    font-size: 0.77rem;
    line-height: 1.5;
  }

  .panel-index {
    color: var(--paper-muted);
    font-family: var(--mono);
    font-size: 0.64rem;
    letter-spacing: 0.1em;
  }

  .field {
    display: grid;
    min-width: 0;
    gap: 0.45rem;
    color: var(--paper-soft);
    font-family: var(--mono);
    font-size: 0.65rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
  }

  .field--full {
    grid-column: 1 / -1;
  }

  .field select,
  .field input:not([type="range"]):not([type="radio"]):not([type="checkbox"]),
  .field textarea {
    width: 100%;
    min-height: 2.75rem;
    padding: 0.65rem 0.75rem;
    border: 1px solid var(--line);
    border-radius: var(--radius-xs);
    color: var(--paper);
    background: var(--ink-0);
    font-family: var(--sans);
    font-size: 0.85rem;
    font-weight: 450;
    letter-spacing: 0;
    line-height: 1.35;
    text-transform: none;
  }

  .field select {
    padding-right: 2rem;
    cursor: pointer;
  }

  .field textarea {
    min-height: 6.5rem;
    resize: vertical;
  }

  .field output {
    justify-self: end;
    color: var(--key);
    font-family: var(--mono);
    font-size: 0.7rem;
  }

  .field input[type="range"] {
    width: 100%;
    height: 1.4rem;
    margin: 0;
    appearance: none;
    background: transparent;
    cursor: pointer;
  }

  .field input[type="range"]::-webkit-slider-runnable-track {
    height: 0.25rem;
    border-radius: 999px;
    background: linear-gradient(90deg, var(--key), var(--line));
  }

  .field input[type="range"]::-moz-range-track {
    height: 0.25rem;
    border-radius: 999px;
    background: linear-gradient(90deg, var(--key), var(--line));
  }

  .field input[type="range"]::-webkit-slider-thumb {
    width: 1rem;
    height: 1rem;
    margin-top: -0.375rem;
    border: 2px solid var(--ink-0);
    border-radius: 50%;
    appearance: none;
    background: var(--key);
    box-shadow: 0 0 0 1px var(--key), 0 0 1rem rgb(200 255 98 / 35%);
  }

  .field input[type="range"]::-moz-range-thumb {
    width: 0.8rem;
    height: 0.8rem;
    border: 2px solid var(--ink-0);
    border-radius: 50%;
    background: var(--key);
    box-shadow: 0 0 0 1px var(--key), 0 0 1rem rgb(200 255 98 / 35%);
  }

  .segmented {
    display: inline-grid;
    grid-auto-columns: 1fr;
    grid-auto-flow: column;
    width: 100%;
    padding: 0.2rem;
    border: 1px solid var(--line);
    border-radius: var(--radius-sm);
    background: var(--ink-0);
  }

  .segmented button,
  .segmented label {
    display: grid;
    min-height: 2.35rem;
    place-items: center;
    padding: 0.45rem 0.65rem;
    border-radius: 0.36rem;
    color: var(--paper-muted);
    background: transparent;
    cursor: pointer;
    font-family: var(--mono);
    font-size: 0.62rem;
    font-weight: 700;
    letter-spacing: 0.06em;
    line-height: 1.2;
    text-align: center;
    text-transform: uppercase;
    transition: 160ms ease;
  }

  .segmented button:hover,
  .segmented label:hover {
    color: var(--paper);
  }

  .segmented button.is-active,
  .segmented button[aria-pressed="true"],
  .segmented label:has(input:checked) {
    color: var(--ink-0);
    background: var(--paper);
  }

  .segmented input {
    position: absolute;
    width: 1px;
    height: 1px;
    opacity: 0;
  }

  .candidate-card {
    position: relative;
    display: grid;
    min-height: 10.5rem;
    gap: 0.7rem;
    align-content: start;
    padding: 1rem;
    border: 1px solid var(--line);
    border-radius: var(--radius-sm);
    color: var(--paper-soft);
    background: var(--ink-1);
    text-align: left;
    transition:
      border-color 180ms ease,
      background-color 180ms ease,
      transform 180ms var(--ease-out);
  }

  button.candidate-card,
  label.candidate-card {
    width: 100%;
    cursor: pointer;
  }

  .candidate-card:hover {
    border-color: #4a5549;
    background: var(--ink-3);
    transform: translateY(-2px);
  }

  .candidate-card.is-selected,
  .candidate-card[aria-pressed="true"],
  .candidate-card:has(input:checked) {
    border-color: var(--key-soft);
    background: var(--key-fade);
    box-shadow: inset 0 0 0 1px rgb(200 255 98 / 12%);
  }

  .candidate-card input[type="radio"],
  .candidate-card input[type="checkbox"] {
    position: absolute;
    top: 0.9rem;
    right: 0.9rem;
    width: 1rem;
    height: 1rem;
    accent-color: var(--key);
  }

  .candidate-kicker {
    color: var(--paper-muted);
    font-family: var(--mono);
    font-size: 0.59rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
  }

  .candidate-content {
    color: var(--paper);
    font-family: var(--serif);
    font-size: 0.98rem;
    line-height: 1.45;
  }

  .lane-title {
    color: var(--paper);
    font-family: var(--serif);
    font-size: clamp(1.35rem, 2.2vw, 1.85rem);
    font-weight: 500;
    letter-spacing: -0.025em;
    line-height: 1.05;
  }

  .benchmark-lane-card {
    min-height: 24rem;
  }

  .metric-list {
    display: grid;
    gap: 0.35rem;
    padding-left: 1.1rem;
    color: var(--paper-soft);
    font-size: 0.75rem;
  }

  .benchmark-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.65rem;
    align-items: center;
    justify-content: space-between;
    margin-top: 1rem;
  }

  .table-scroll {
    max-width: 100%;
    border: 1px solid var(--line-soft);
    border-radius: var(--radius-sm);
    overflow-x: auto;
  }

  .benchmark-table {
    width: 100%;
    border-collapse: collapse;
    color: var(--paper-soft);
    font-size: 0.72rem;
    font-variant-numeric: tabular-nums;
  }

  .benchmark-table th,
  .benchmark-table td {
    padding: 0.65rem 0.75rem;
    border-bottom: 1px solid var(--line-soft);
    text-align: left;
  }

  .benchmark-table thead th {
    color: var(--paper-muted);
    background: rgb(0 0 0 / 16%);
    font-family: var(--mono);
    font-size: 0.58rem;
    letter-spacing: 0.07em;
    text-transform: uppercase;
  }

  .benchmark-table tbody th {
    color: var(--paper);
    font-weight: 600;
  }

  .benchmark-table tr:last-child th,
  .benchmark-table tr:last-child td {
    border-bottom: 0;
  }

  .candidate-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
    margin-top: auto;
  }

  .annotation-list {
    display: grid;
    gap: 0;
    list-style: none;
  }

  .annotation-list > li,
  .annotation-item {
    position: relative;
    display: grid;
    grid-template-columns: 0.7rem minmax(0, 1fr) auto;
    gap: 0.65rem;
    align-items: baseline;
    padding: 0.72rem 0;
    border-bottom: 1px solid var(--line-soft);
    color: var(--paper-soft);
    font-size: 0.78rem;
  }

  .annotation-list > li::before,
  .annotation-marker {
    width: 0.48rem;
    height: 0.48rem;
    border: 1px solid var(--key);
    border-radius: 50%;
    content: "";
    box-shadow: 0 0 0 0.2rem var(--key-fade);
  }

  .annotation-list > li:last-child,
  .annotation-item:last-child {
    border-bottom: 0;
  }

  .annotation-source {
    color: var(--paper-muted);
    font-family: var(--mono);
    font-size: 0.58rem;
    letter-spacing: 0.05em;
    white-space: nowrap;
  }

  .loss-stack {
    display: grid;
    gap: 0.5rem;
  }

  .loss-item {
    position: relative;
    display: grid;
    grid-template-columns: minmax(7rem, 0.7fr) minmax(0, 1.3fr) auto;
    gap: 0.75rem;
    align-items: center;
    min-height: 3.25rem;
    padding: 0.65rem 0.75rem;
    border: 1px solid var(--line-soft);
    border-radius: var(--radius-xs);
    color: var(--paper-soft);
    background: rgb(0 0 0 / 14%);
    font-size: 0.72rem;
  }

  .loss-item::before {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    width: 2px;
    border-radius: inherit;
    background: var(--cage);
    content: "";
    opacity: 0.8;
  }

  .loss-label {
    color: var(--paper);
    font-weight: 650;
  }

  .loss-value {
    color: var(--cage);
    font-family: var(--mono);
    font-size: 0.66rem;
    font-weight: 700;
  }

  .metric-card {
    min-width: 0;
    padding: 0.8rem;
    border: 1px solid var(--line-soft);
    border-radius: var(--radius-sm);
    background: rgb(0 0 0 / 16%);
  }

  .metric-label {
    display: block;
    margin-bottom: 0.45rem;
    color: var(--paper-muted);
    font-family: var(--mono);
    font-size: 0.57rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    line-height: 1.35;
    text-transform: uppercase;
  }

  .metric-value {
    display: block;
    color: var(--paper);
    font-family: var(--serif);
    font-size: clamp(1.45rem, 2.7vw, 2.15rem);
    font-variant-numeric: tabular-nums;
    letter-spacing: -0.035em;
    line-height: 1;
  }

  .metric-delta {
    display: block;
    margin-top: 0.45rem;
    color: var(--key-soft);
    font-family: var(--mono);
    font-size: 0.58rem;
    font-variant-numeric: tabular-nums;
  }

  .metric-delta.is-negative {
    color: var(--cage);
  }

  .bar {
    position: relative;
    width: 100%;
    height: 0.35rem;
    border-radius: 999px;
    background: var(--ink-4);
    overflow: hidden;
  }

  .bar > span,
  .bar-fill {
    display: block;
    width: var(--value, 0%);
    height: 100%;
    border-radius: inherit;
    background: var(--key);
    box-shadow: 0 0 0.8rem rgb(200 255 98 / 35%);
    transform-origin: left;
    animation: bar-grow 680ms var(--ease-out) both;
  }

  .bar.is-loss > span,
  .bar.is-loss .bar-fill {
    background: var(--cage);
    box-shadow: 0 0 0.8rem rgb(255 120 90 / 28%);
  }

  .bar.is-signal > span,
  .bar.is-signal .bar-fill {
    background: var(--signal);
    box-shadow: 0 0 0.8rem rgb(120 191 255 / 28%);
  }

  .chart {
    position: relative;
    min-height: 17rem;
    padding: 0.75rem;
    border: 1px solid var(--line-soft);
    border-radius: var(--radius-sm);
    background:
      linear-gradient(var(--line-soft) 1px, transparent 1px),
      linear-gradient(90deg, var(--line-soft) 1px, transparent 1px),
      var(--ink-1);
    background-size: 2.5rem 2.5rem;
    overflow: hidden;
  }

  .chart::after {
    position: absolute;
    inset: 0;
    border-radius: inherit;
    background: linear-gradient(90deg, transparent, rgb(200 255 98 / 3%), transparent);
    content: "";
    pointer-events: none;
  }

  .chart svg {
    width: 100%;
    height: 100%;
    min-height: 15rem;
    overflow: visible;
  }

  .chart text {
    fill: var(--paper-muted);
    font-family: var(--mono);
    font-size: 0.62rem;
  }

  .chart .grid-line,
  .chart .axis-line {
    stroke: var(--line);
    vector-effect: non-scaling-stroke;
  }

  .chart .proxy-line,
  .chart .key-line {
    fill: none;
    stroke: var(--key);
    stroke-linecap: round;
    stroke-linejoin: round;
    stroke-width: 2.5;
    vector-effect: non-scaling-stroke;
  }

  .chart .holdout-line,
  .chart .signal-line {
    fill: none;
    stroke: var(--signal);
    stroke-dasharray: 5 5;
    stroke-linecap: round;
    stroke-linejoin: round;
    stroke-width: 2;
    vector-effect: non-scaling-stroke;
  }

  .chart .loss-line {
    fill: none;
    stroke: var(--cage);
    stroke-linecap: round;
    stroke-linejoin: round;
    stroke-width: 2;
    vector-effect: non-scaling-stroke;
  }

  .legend {
    display: flex;
    flex-wrap: wrap;
    gap: 0.55rem 1rem;
    align-items: center;
    margin-top: 0.75rem;
    color: var(--paper-muted);
    font-family: var(--mono);
    font-size: 0.59rem;
    letter-spacing: 0.04em;
  }

  .legend-item {
    display: inline-flex;
    gap: 0.4rem;
    align-items: center;
  }

  .legend-swatch {
    width: 1.15rem;
    height: 2px;
    background: var(--key);
  }

  .legend-swatch.is-signal {
    background: var(--signal);
  }

  .legend-swatch.is-loss {
    background: var(--cage);
  }

  .receipt {
    position: relative;
    padding: clamp(1rem, 2vw, 1.5rem);
    border: 1px solid var(--key-soft);
    border-radius: var(--radius-sm);
    background:
      linear-gradient(135deg, var(--key-fade), transparent 45%),
      var(--ink-1);
    box-shadow: inset 0 0 2.5rem rgb(200 255 98 / 3%);
  }

  .receipt::before,
  .receipt::after {
    position: absolute;
    left: 0;
    width: 100%;
    height: 4px;
    background: repeating-linear-gradient(90deg, var(--ink-0) 0 5px, transparent 5px 10px);
    content: "";
  }

  .receipt::before {
    top: -2px;
  }

  .receipt::after {
    bottom: -2px;
  }

  .receipt-grid {
    display: grid;
    grid-template-columns: minmax(8rem, 0.7fr) minmax(0, 1.3fr);
    gap: 0;
  }

  .receipt-row {
    display: contents;
  }

  .receipt-key,
  .receipt-value {
    padding: 0.58rem 0;
    border-bottom: 1px dashed var(--line);
    font-size: 0.7rem;
  }

  .receipt-key {
    color: var(--paper-muted);
    font-family: var(--mono);
    letter-spacing: 0.06em;
    text-transform: uppercase;
  }

  .receipt-value {
    min-width: 0;
    color: var(--paper);
    overflow-wrap: anywhere;
  }

  .code-block {
    max-width: 100%;
    margin: 0;
    padding: 1rem;
    border: 1px solid var(--line);
    border-radius: var(--radius-sm);
    color: var(--key-soft);
    background: var(--ink-0);
    font-family: var(--mono);
    font-size: clamp(0.68rem, 1.4vw, 0.78rem);
    line-height: 1.65;
    white-space: pre-wrap;
    overflow: auto;
    overflow-wrap: anywhere;
    tab-size: 2;
  }

  .badge,
  .pill {
    display: inline-flex;
    max-width: 100%;
    min-height: 1.4rem;
    gap: 0.3rem;
    align-items: center;
    padding: 0.2rem 0.48rem;
    border: 1px solid var(--line);
    border-radius: 999px;
    color: var(--paper-muted);
    background: rgb(0 0 0 / 18%);
    font-family: var(--mono);
    font-size: 0.54rem;
    font-weight: 700;
    letter-spacing: 0.06em;
    line-height: 1.15;
    text-transform: uppercase;
  }

  .badge.is-key,
  .pill.is-key {
    border-color: rgb(200 255 98 / 40%);
    color: var(--key);
    background: var(--key-fade);
  }

  .badge.is-loss,
  .pill.is-loss {
    border-color: rgb(255 120 90 / 40%);
    color: var(--cage);
    background: var(--cage-fade);
  }

  .badge.is-signal,
  .pill.is-signal {
    border-color: rgb(120 191 255 / 40%);
    color: var(--signal);
    background: var(--signal-fade);
  }

  .button-group {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
    align-items: center;
  }

  .primary-button,
  .secondary-button {
    display: inline-flex;
    min-height: 2.7rem;
    gap: 0.45rem;
    align-items: center;
    justify-content: center;
    padding: 0.65rem 0.9rem;
    border: 1px solid var(--key);
    border-radius: var(--radius-xs);
    color: var(--ink-0);
    background: var(--key);
    cursor: pointer;
    font-family: var(--mono);
    font-size: 0.63rem;
    font-weight: 800;
    letter-spacing: 0.07em;
    line-height: 1.2;
    text-transform: uppercase;
    transition:
      transform 180ms var(--ease-out),
      box-shadow 180ms ease,
      background-color 180ms ease;
  }

  .primary-button:hover {
    background: #d7ff8d;
    box-shadow: 0 0 1.5rem rgb(200 255 98 / 16%);
    transform: translateY(-1px);
  }

  .secondary-button {
    border-color: var(--line);
    color: var(--paper-soft);
    background: transparent;
  }

  .secondary-button:hover {
    border-color: var(--paper-muted);
    color: var(--paper);
    background: rgb(255 255 255 / 4%);
  }

  .footer {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 1rem;
    align-items: end;
    margin-top: clamp(2.5rem, 6vw, 5rem);
    padding: 1.4rem 0 0 clamp(0.85rem, 2vw, 1.5rem);
    border-top: 1px solid var(--line);
    color: var(--paper-muted);
    font-family: var(--mono);
    font-size: 0.62rem;
    line-height: 1.55;
  }

  .empty-state {
    display: grid;
    min-height: 12rem;
    place-items: center;
    padding: 2rem;
    border: 1px dashed var(--line);
    border-radius: var(--radius-sm);
    color: var(--paper-muted);
    font-family: var(--serif);
    font-style: italic;
    text-align: center;
  }

  .skip-link {
    position: fixed;
    z-index: 100;
    top: 0.75rem;
    left: 0.75rem;
    padding: 0.65rem 0.85rem;
    border: 2px solid var(--ink-0);
    border-radius: var(--radius-xs);
    color: var(--ink-0);
    background: var(--key);
    box-shadow: 0 0 0 2px var(--key);
    font-family: var(--mono);
    font-size: 0.7rem;
    font-weight: 800;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    transform: translateY(calc(-100% - 1rem));
    transition: transform 160ms var(--ease-out);
  }

  .skip-link:focus {
    transform: translateY(0);
  }
}

@layer states {
  [hidden] {
    display: none !important;
  }

  button:disabled,
  input:disabled,
  select:disabled,
  textarea:disabled {
    cursor: not-allowed;
    filter: saturate(0.25);
    opacity: 0.52;
  }

  .is-loading {
    cursor: progress;
  }

  .is-loading::before {
    display: inline-block;
    width: 0.75rem;
    height: 0.75rem;
    border: 1px solid currentColor;
    border-right-color: transparent;
    border-radius: 50%;
    content: "";
    animation: spin 750ms linear infinite;
  }

  @keyframes panel-in {
    from {
      opacity: 0;
      transform: translateY(0.75rem);
    }

    to {
      opacity: 1;
      transform: translateY(0);
    }
  }

  @keyframes bar-grow {
    from {
      transform: scaleX(0);
    }

    to {
      transform: scaleX(1);
    }
  }

  @keyframes spin {
    to {
      transform: rotate(1turn);
    }
  }
}

@layer accessibility {
  :where(a, button, input, select, textarea, [tabindex]):focus-visible {
    outline: 3px solid var(--signal);
    outline-offset: 3px;
  }

  .candidate-card:has(input:focus-visible),
  .segmented label:has(input:focus-visible) {
    outline: 3px solid var(--signal);
    outline-offset: 3px;
  }

  .sr-only {
    position: absolute !important;
    width: 1px !important;
    height: 1px !important;
    padding: 0 !important;
    border: 0 !important;
    margin: -1px !important;
    clip: rect(0, 0, 0, 0) !important;
    clip-path: inset(50%) !important;
    white-space: nowrap !important;
    overflow: hidden !important;
  }

  @media (prefers-reduced-motion: reduce) {
    html {
      scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
      scroll-behavior: auto !important;
      animation-duration: 0.01ms !important;
      animation-iteration-count: 1 !important;
      transition-duration: 0.01ms !important;
    }
  }

  @media (prefers-contrast: more) {
    :root {
      --line: #697267;
      --line-soft: rgb(241 241 231 / 30%);
      --paper-soft: #e1e3d8;
      --paper-muted: #bac0b3;
    }

    .panel,
    .candidate-card,
    .metric-card,
    .boundary-note,
    .chart {
      border-width: 2px;
    }
  }

  @media (forced-colors: active) {
    :root {
      --key: LinkText;
      --cage: Mark;
      --signal: Highlight;
    }

    body::before,
    .app-shell::before,
    .panel::after,
    .receipt::before,
    .receipt::after {
      display: none;
    }

    .stage-button.is-active,
    .stage-button[aria-selected="true"],
    .stage-button[aria-current="step"],
    .candidate-card.is-selected,
    .candidate-card[aria-pressed="true"] {
      border: 2px solid Highlight;
    }

    .primary-button {
      border: 2px solid ButtonText;
    }
  }
}

@media (max-width: 68rem) {
  .masthead {
    grid-template-columns: minmax(0, 1.25fr) minmax(15rem, 0.75fr);
  }

  .main-grid > .panel,
  .main-grid > .panel--wide,
  .main-grid > .panel--narrow,
  .main-grid > .span-8,
  .main-grid > .span-4 {
    grid-column: span 6;
  }

  .main-grid > .panel--full,
  .main-grid > .span-full {
    grid-column: 1 / -1;
  }

  .metric-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

  .benchmark-lane-card {
    min-height: 0;
  }
}

@media (max-width: 48rem) {
  .app-shell {
    padding-top: 0.75rem;
  }

  .masthead {
    grid-template-columns: 1fr;
    gap: 1.6rem;
    align-items: start;
    padding-top: 3.25rem;
  }

  .title {
    max-width: 10ch;
    font-size: clamp(3.2rem, 15vw, 5.75rem);
  }

  .boundary-note {
    max-width: 35rem;
  }

  .stage-nav {
    grid-template-columns: repeat(6, minmax(0, 1fr));
    overflow-x: visible;
  }

  .stage-button {
    grid-column: span 2;
    min-width: 0;
    min-height: 4.3rem;
    flex-direction: column;
    gap: 0.45rem;
    align-items: flex-start;
    justify-content: center;
    padding-inline: 0.65rem;
    font-size: 0.58rem;
    letter-spacing: 0.035em;
  }

  .stage-button::before {
    width: 1.55rem;
    height: 1.55rem;
  }

  .main-grid > .panel,
  .main-grid > .panel--wide,
  .main-grid > .panel--narrow,
  .main-grid > .span-8,
  .main-grid > .span-4,
  .main-grid > .panel--full,
  .main-grid > .span-full {
    grid-column: 1 / -1;
  }

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

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

  .candidate-card {
    min-height: 8rem;
  }

  .footer {
    grid-template-columns: 1fr;
    align-items: start;
  }
}

@media (max-width: 34rem) {
  .app-shell {
    --gutter: 0.8rem;
  }

  .masthead {
    padding-left: 0.6rem;
  }

  .title {
    font-size: clamp(2.95rem, 17vw, 4.7rem);
  }

  .subtitle {
    font-size: 1.03rem;
  }

  .panel {
    padding: 0.9rem;
    border-radius: var(--radius-sm);
  }

  .panel-header {
    margin: -0.9rem -0.9rem 1rem;
    padding: 0.8rem 0.9rem;
  }

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

  .loss-item {
    grid-template-columns: 1fr auto;
  }

  .loss-item .bar {
    grid-column: 1 / -1;
    grid-row: 2;
  }

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

  .receipt-row {
    display: grid;
    padding: 0.55rem 0;
    border-bottom: 1px dashed var(--line);
  }

  .receipt-key,
  .receipt-value {
    padding: 0;
    border: 0;
  }

  .segmented {
    grid-auto-flow: row;
    grid-auto-rows: 1fr;
  }
}