/* ==========================================================================
   DSA Field Notes - visual shell
   Token names and class names are contracts with the inline SVG diagrams.
   Teal (--ptr) = a pointer that already existed.
   Orange (--new) = what changed in this step.
   Red (--null) = None.
   ========================================================================== */

:root {
    --bg: #F6F8FB;
    --surface: #FFFFFF;
    --ink: #121821;
    --muted: #55616F;
    --line: #D8E0E9;
    --ptr: #0E7C7B;
    --ptr-soft: #DCEFEE;
    --new: #B25E08;
    --new-soft: #FBEBD9;
    --null: #B3302A;
    --code-bg: #F0F3F7;
    --code-ink: #121821;
    --kw: #7A3E9D;
    --str: #0E7C7B;
    --cmt: #616E7C;
    --shadow: 0 1px 2px rgba(18, 24, 33, .05), 0 1px 8px rgba(18, 24, 33, .03);
    /* additions: never referenced by the diagrams */
    --pad: 20px;
    --radius: 12px;
    --edge-fade: rgba(18, 24, 33, .16);
    --sans: "Source Sans 3", -apple-system, BlinkMacSystemFont, "SF Pro Text",
            "Helvetica Neue", "Segoe UI", system-ui, sans-serif;
    --display: "Bricolage Grotesque", -apple-system, BlinkMacSystemFont,
               "SF Pro Display", "Helvetica Neue", "Segoe UI", system-ui, sans-serif;
    --mono: "JetBrains Mono", ui-monospace, "SF Mono", SFMono-Regular, Menlo,
            Consolas, monospace;
    color-scheme: light;
  }
  @media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
      --bg: #0F141A;
      --surface: #161D26;
      --ink: #E8EDF3;
      --muted: #9AA7B5;
      --line: #2B3542;
      --ptr: #4CC3BF;
      --ptr-soft: #14302F;
      --new: #F0A050;
      --new-soft: #3A2A16;
      --null: #F27D75;
      --code-bg: #0B1016;
      --code-ink: #E8EDF3;
      --kw: #C79BE0;
      --str: #5FD3CF;
      --cmt: #8A97A6;
      --shadow: 0 1px 2px rgba(0, 0, 0, .34), 0 1px 8px rgba(0, 0, 0, .22);
      --edge-fade: rgba(0, 0, 0, .5);
      color-scheme: dark;
    }
  }
  :root[data-theme="dark"] {
    --bg: #0F141A;
    --surface: #161D26;
    --ink: #E8EDF3;
    --muted: #9AA7B5;
    --line: #2B3542;
    --ptr: #4CC3BF;
    --ptr-soft: #14302F;
    --new: #F0A050;
    --new-soft: #3A2A16;
    --null: #F27D75;
    --code-bg: #0B1016;
    --code-ink: #E8EDF3;
    --kw: #C79BE0;
    --str: #5FD3CF;
    --cmt: #8A97A6;
    --shadow: 0 1px 2px rgba(0, 0, 0, .34), 0 1px 8px rgba(0, 0, 0, .22);
    --edge-fade: rgba(0, 0, 0, .5);
    color-scheme: dark;
  }

  /* ---------------------------------------------------------------- base */
  * { box-sizing: border-box; }
  html {
    -webkit-text-size-adjust: 100%;
    text-size-adjust: 100%;
  }
  body {
    margin: 0;
    background: var(--bg);
    color: var(--ink);
    font-family: var(--sans);
    font-size: 17px;
    line-height: 1.65;
    -webkit-tap-highlight-color: transparent;
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
  }
  @media (min-width: 1024px) {
    body { font-size: 18px; }
  }

  .wrap {
    max-width: 1120px;
    margin: 0 auto;
    padding-inline: max(var(--pad), env(safe-area-inset-left))
                    max(var(--pad), env(safe-area-inset-right));
    padding-block: 0 calc(72px + env(safe-area-inset-bottom));
  }

  a { color: var(--ptr); }
  :where(a, button, summary, input, label):focus-visible {
    outline: 2px solid var(--ptr);
    outline-offset: 2px;
    border-radius: 4px;
  }

  /* ------------------------------------------------- reading progress bar */
  .progress-bar {
    position: fixed;
    top: env(safe-area-inset-top, 0px);
    left: 0;
    z-index: 20;
    width: 100%;
    height: 3px;
    background: var(--ptr);
    transform: scaleX(0);
    transform-origin: 0 50%;
    will-change: transform;
    pointer-events: none;
  }
  @media (prefers-reduced-motion: no-preference) {
    .progress-bar { transition: transform .08s linear; }
  }

  /* ------------------------------------------------------------ typography */
  h1 {
    font-family: var(--display);
    font-weight: 700;
    font-size: clamp(30px, 7vw, 42px);
    line-height: 1.08;
    letter-spacing: -.015em;
    margin: 6px 0 12px;
    text-wrap: balance;
  }
  h2 {
    font-family: var(--display);
    font-weight: 700;
    font-size: clamp(23px, 4.4vw, 29px);
    line-height: 1.15;
    letter-spacing: -.012em;
    margin: 0 0 8px;
    text-wrap: balance;
  }
  h2 .num { color: var(--ptr); margin-right: 10px; }
  h3 {
    font-family: var(--display);
    font-weight: 700;
    font-size: clamp(18px, 2.6vw, 21px);
    line-height: 1.25;
    margin: 32px 0 8px;
    text-wrap: balance;
  }
  p { margin: 0 0 15px; max-width: 68ch; }
  ul, ol { margin: 0 0 15px; padding-left: 24px; max-width: 68ch; }
  li { margin-bottom: 6px; }
  strong { font-weight: 600; }
  em { font-style: italic; }
  dfn {
    font-style: normal;
    font-weight: 600;
    border-bottom: 2px solid var(--ptr-soft);
  }
  .eyebrow {
    font-family: var(--mono);
    font-size: 12px;
    font-weight: 600;
    letter-spacing: .1em;
    text-transform: uppercase;
    color: var(--ptr);
  }
  .lede {
    font-size: clamp(17px, 2.4vw, 19px);
    color: var(--muted);
    margin: 0;
    max-width: 62ch;
  }

  header.top { padding-block: 26px 14px; }
  section { padding-block: 34px 6px; scroll-margin-top: 68px; }

  /* ----------------------------------------------------------- site chrome */
  .site-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px 16px;
    padding-block: 12px;
    border-bottom: 1px solid var(--line);
    flex-wrap: wrap;
  }
  .site-head .brand {
    font-family: var(--display);
    font-weight: 700;
    font-size: 17px;
    color: var(--ink);
    text-decoration: none;
    letter-spacing: -.01em;
    padding-block: 6px;
  }
  .site-head .brand span { color: var(--ptr); }
  .site-head .crumbs {
    display: flex;
    gap: 8px;
    align-items: center;
    font-size: 13.5px;
    color: var(--muted);
    flex-wrap: wrap;
  }
  .site-head .crumbs a {
    color: var(--muted);
    text-decoration: none;
    font-weight: 600;
    padding-block: 6px;
  }
  .site-head .crumbs a:hover { color: var(--ptr); }

  /* ------------------------------------------------------ layout + sidebar */
  .content { min-width: 0; }

  /* phone and tablet: section links are a sticky chip bar */
  nav.sections {
    position: sticky;
    top: 0;
    z-index: 6;
    display: flex;
    gap: 6px;
    margin-inline: calc(-1 * max(var(--pad), env(safe-area-inset-left)))
                   calc(-1 * max(var(--pad), env(safe-area-inset-right)));
    padding: 8px max(var(--pad), env(safe-area-inset-right)) 8px
                 max(var(--pad), env(safe-area-inset-left));
    background: color-mix(in srgb, var(--bg) 88%, transparent);
    backdrop-filter: saturate(140%) blur(8px);
    -webkit-backdrop-filter: saturate(140%) blur(8px);
    border-bottom: 1px solid var(--line);
    overflow-x: auto;
    overscroll-behavior-x: contain;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }
  nav.sections::-webkit-scrollbar { display: none; }
  nav.sections a {
    flex: 0 0 auto;
    display: inline-flex;
    align-items: center;
    min-height: 34px;
    padding: 4px 13px;
    font-size: 14px;
    font-weight: 600;
    color: var(--muted);
    text-decoration: none;
    border: 1px solid transparent;
    border-radius: 999px;
    white-space: nowrap;
  }
  nav.sections a:hover { color: var(--ptr); border-color: var(--line); }
  nav.sections a.is-active {
    color: var(--ptr);
    background: var(--ptr-soft);
    border-color: color-mix(in srgb, var(--ptr) 30%, transparent);
  }
  nav.sections a.home { color: var(--ink); }
  nav.sections a.home::before { content: "\2190"; margin-right: 6px; }

  /* desktop: the same element becomes a sticky left sidebar */
  @media (min-width: 1024px) {
    .layout {
      display: grid;
      grid-template-columns: auto minmax(0, 760px);
      column-gap: 0;
      justify-content: center;
      align-items: start;
    }
    .content { grid-column: 2; }
    nav.sections {
      grid-column: 1;
      grid-row: 1;
      position: sticky;
      top: 24px;
      display: flex;
      flex-direction: column;
      gap: 2px;
      width: 240px;
      margin: 34px 44px 0 0;
      padding: 0;
      max-height: calc(100dvh - 64px);
      overflow-y: auto;
      overflow-x: hidden;
      background: none;
      backdrop-filter: none;
      -webkit-backdrop-filter: none;
      border-bottom: 0;
      border-left: 1px solid var(--line);
    }
    nav.sections a {
      width: 100%;
      min-height: 36px;
      margin-left: -1px;
      padding: 5px 14px;
      border: 0;
      border-left: 2px solid transparent;
      border-radius: 0 6px 6px 0;
      white-space: normal;
    }
    nav.sections a:hover { background: var(--ptr-soft); border-color: transparent; }
    nav.sections a.is-active {
      background: none;
      border-left-color: var(--ptr);
      border-radius: 0;
    }
    nav.sections a.home {
      margin-bottom: 8px;
      padding-bottom: 10px;
      border-bottom: 1px solid var(--line);
      border-radius: 0;
    }
    section { scroll-margin-top: 24px; }
  }

  /* ------------------------------------------------------------ cards etc. */
  .analogy {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 14px;
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 16px 18px;
    margin: 14px 0 22px;
    box-shadow: var(--shadow);
  }
  .analogy .tag {
    font-family: var(--mono);
    font-size: 11px;
    font-weight: 600;
    letter-spacing: .1em;
    text-transform: uppercase;
    color: var(--ptr);
    padding-top: 5px;
  }
  .analogy p { margin: 0; }
  /* on a phone the label column would leave the text too narrow */
  @media (max-width: 560px) {
    .analogy { grid-template-columns: 1fr; gap: 5px; }
    .analogy .tag { padding-top: 0; }
  }

  .callout {
    border: 1px solid color-mix(in srgb, var(--new) 24%, transparent);
    border-left: 3px solid var(--new);
    background: var(--new-soft);
    padding: 13px 16px;
    border-radius: var(--radius);
    margin: 16px 0 20px;
    max-width: 68ch;
  }
  .callout.keep {
    border-color: color-mix(in srgb, var(--ptr) 24%, transparent);
    border-left-color: var(--ptr);
    background: var(--ptr-soft);
  }
  .callout p { margin: 0; }
  .callout p + p { margin-top: 8px; }
  .callout .lab {
    font-family: var(--mono);
    font-size: 11px;
    font-weight: 600;
    letter-spacing: .1em;
    text-transform: uppercase;
    display: block;
    margin-bottom: 5px;
    color: var(--new);
  }
  .callout.keep .lab { color: var(--ptr); }

  /* ------------------------------------------------------------- code */
  .codewrap { position: relative; margin: 12px 0 20px; }
  .codewrap pre { margin: 0; }

  pre {
    margin: 12px 0 20px;
    padding: 14px 16px;
    color: var(--code-ink);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    font-family: var(--mono);
    font-size: 14px;
    line-height: 1.6;
    tab-size: 4;
    white-space: pre;
    overflow-x: auto;
    overscroll-behavior-x: contain;
    -webkit-overflow-scrolling: touch;
    /* right-edge fade that disappears once scrolled to the end */
    background-color: var(--code-bg);
    background-image:
      linear-gradient(to left, var(--code-bg), var(--code-bg)),
      linear-gradient(to left, var(--edge-fade), transparent);
    background-position: right center, right center;
    background-repeat: no-repeat;
    background-size: 28px 100%, 22px 100%;
    background-attachment: local, scroll;
  }
  @media (min-width: 1024px) {
    pre { font-size: 15px; }
  }
  code {
    font-family: var(--mono);
    font-size: .92em;
    background: var(--code-bg);
    padding: 1px 5px;
    border-radius: 5px;
    /* a long identifier in running prose must never widen the page */
    overflow-wrap: break-word;
  }
  pre code {
    background: none;
    padding: 0;
    font-size: inherit;
    overflow-wrap: normal;
  }
  .k { color: var(--kw); } .s { color: var(--str); } .c { color: var(--cmt); font-style: italic; }
  .hl { background: var(--new-soft); display: inline-block; width: 100%; }

  .copy-btn {
    position: absolute;
    top: 7px;
    right: 7px;
    z-index: 2;
    min-height: 30px;
    padding: 5px 9px;
    font-family: var(--mono);
    font-size: 11px;
    font-weight: 600;
    letter-spacing: .07em;
    text-transform: uppercase;
    color: var(--muted);
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: 7px;
    cursor: pointer;
  }
  .copy-btn:hover { color: var(--ptr); border-color: var(--ptr); }
  .copy-btn.ok { color: var(--ptr); border-color: var(--ptr); }

  /* ------------------------------------------------------------- figures */
  figure {
    position: relative;
    margin: 18px 0 22px;
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 14px 14px 10px;
    box-shadow: var(--shadow);
    overflow-x: auto;
    overscroll-behavior-x: contain;
    -webkit-overflow-scrolling: touch;
  }
  figure svg {
    display: block;
    max-width: 100%;
    height: auto;
    margin: 0 auto;
    font-family: var(--mono);
  }
  figcaption {
    font-size: 14px;
    color: var(--muted);
    margin-top: 10px;
    line-height: 1.5;
    max-width: 68ch;
  }
  figcaption b { color: var(--ink); font-weight: 600; }

  /* Phone: render diagrams at a legible size and let the figure scroll.
     The hint sits in the scrolled area, so it leaves after the first swipe. */
  @media (max-width: 720px) {
    figure { padding: 30px 10px 8px; }
    figure svg { max-width: none; min-width: 640px; margin: 0; }
    figure::after {
      content: "swipe \2192";
      position: absolute;
      top: 9px;
      left: 11px;
      font-family: var(--mono);
      font-size: 11px;
      font-weight: 600;
      letter-spacing: .08em;
      text-transform: uppercase;
      color: var(--muted);
    }
    /* the figure scrolls, but the caption stays put and stays readable */
    figcaption {
      position: sticky;
      left: 0;
      width: min(100%, calc(100dvw - 62px));
    }
  }

  /* --------------------------------------------------------- SVG vocabulary */
  .nd { fill: var(--surface); stroke: currentColor; stroke-width: 1.4; }
  .nd.dim { opacity: .35; }
  .nd.newnd { stroke: var(--new); stroke-width: 2; }
  .cell { stroke: currentColor; stroke-width: 1; }
  .t { fill: currentColor; font-size: 13px; }
  .t.small { font-size: 11px; fill: var(--muted); }
  .t.mono { font-size: 12px; }
  .t.ptrlab { fill: var(--ptr); font-weight: 600; }
  .t.newlab { fill: var(--new); font-weight: 600; }
  .t.nulltxt { fill: var(--null); font-weight: 600; }
  .ptr { stroke: var(--ptr); stroke-width: 2; fill: none; }
  .ptr.newp { stroke: var(--new); }
  .ptr.old { stroke: var(--muted); stroke-dasharray: 5 4; opacity: .6; }
  .ptr.prevp { stroke: var(--ptr); opacity: .55; }
  .dot { fill: var(--ptr); }
  .dot.newd { fill: var(--new); }
  .arr { fill: var(--ptr); }
  .arrNew { fill: var(--new); }
  .arrOld { fill: var(--muted); opacity: .6; }
  .arrCur { fill: currentColor; }
  .cur { stroke: currentColor; stroke-width: 1.6; fill: none; }
  .mem { fill: none; stroke: var(--line); stroke-dasharray: 3 3; }

  /* -------------------------------------------------------------- tables */
  .tbl {
    margin: 12px 0 22px;
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    overflow-x: auto;
    overscroll-behavior-x: contain;
    -webkit-overflow-scrolling: touch;
    background-image:
      linear-gradient(to left, var(--surface), var(--surface)),
      linear-gradient(to left, var(--edge-fade), transparent);
    background-position: right center, right center;
    background-repeat: no-repeat;
    background-size: 28px 100%, 20px 100%;
    background-attachment: local, scroll;
  }
  table {
    border-collapse: collapse;
    width: 100%;
    margin: 0;
    font-size: 15px;
    background: var(--surface);
    border: 0;
  }
  .tbl table { min-width: 100%; }
  th, td {
    text-align: left;
    padding: 10px 13px;
    border-bottom: 1px solid var(--line);
    vertical-align: top;
  }
  th {
    font-size: 11.5px;
    letter-spacing: .07em;
    text-transform: uppercase;
    color: var(--muted);
    font-weight: 600;
    background: var(--code-bg);
    white-space: nowrap;
  }
  tr:last-child td { border-bottom: none; }
  td code { white-space: nowrap; }
  /* keep the row label readable while the rest of a wide table scrolls */
  .tbl th:first-child, .tbl td:first-child {
    position: sticky;
    left: 0;
    min-width: 7.5em;
    background: var(--surface);
    border-right: 1px solid var(--line);
  }
  .tbl th:first-child { background: var(--code-bg); }
  .big { font-family: var(--mono); font-weight: 600; }
  .big.fast { color: var(--ptr); }
  .big.slow { color: var(--null); }

  /* --------------------------------------------------------------- steps */
  .steps { counter-reset: step; list-style: none; padding: 0; margin: 12px 0 20px; }
  .steps li { counter-increment: step; position: relative; padding-left: 42px; margin-bottom: 11px; }
  .steps li::before {
    content: counter(step);
    position: absolute;
    left: 0;
    top: 2px;
    width: 27px;
    height: 27px;
    border-radius: 50%;
    background: var(--ptr);
    color: #fff;
    font-family: var(--mono);
    font-size: 13px;
    font-weight: 600;
    display: grid;
    place-items: center;
  }

  /* ------------------------------------------------------------- details */
  details {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 4px 16px;
    margin-bottom: 10px;
  }
  details[open] { padding-bottom: 14px; }
  /* block, not flex: inline <code> inside a question must be allowed to wrap */
  summary {
    display: block;
    position: relative;
    cursor: pointer;
    font-weight: 600;
    list-style: none;
    min-height: 48px;
    padding: 12px 32px 12px 0;
  }
  summary::-webkit-details-marker { display: none; }
  summary .q {
    font-family: var(--mono);
    font-size: 12px;
    color: var(--ptr);
    margin-right: 9px;
  }
  summary::after {
    content: "";
    position: absolute;
    top: 50%;
    right: 8px;
    width: 9px;
    height: 9px;
    border-right: 2px solid var(--muted);
    border-bottom: 2px solid var(--muted);
    transform: translateY(-70%) rotate(45deg);
  }
  details[open] summary::after { transform: translateY(-30%) rotate(-135deg); }
  details > div {
    padding-top: 11px;
    border-top: 1px solid var(--line);
    margin-top: 4px;
  }
  details p:last-child { margin-bottom: 0; }
  @media (prefers-reduced-motion: no-preference) {
    summary::after { transition: transform .2s ease; }
    details[open] > div { animation: reveal .2s ease both; }
    @keyframes reveal {
      from { opacity: 0; transform: translateY(-4px); }
      to   { opacity: 1; transform: none; }
    }
  }

  /* ------------------------------------------------------------ mistakes */
  .mistake { display: grid; grid-template-columns: 1fr; gap: 10px; }
  .mistake > div {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 13px 15px;
  }
  .mistake .bad {
    color: var(--null);
    font-weight: 600;
    font-size: 12px;
    letter-spacing: .07em;
    text-transform: uppercase;
  }
  .mistake p { margin: 5px 0 0; }
  .mistake pre { margin: 10px 0 0; }

  .cheat {
    background: var(--ink);
    color: var(--bg);
    border-radius: var(--radius);
    padding: 18px 20px;
    margin: 16px 0 24px;
  }
  .cheat h3 { margin: 0 0 10px; color: inherit; }
  .cheat ul { margin: 0; padding-left: 20px; max-width: none; }
  .cheat li { margin-bottom: 7px; }
  .cheat code { background: rgba(255, 255, 255, .14); color: inherit; }
  :root[data-theme="dark"] .cheat, :root:not([data-theme="light"]) .cheat { }

  /* --------------------------------------------------------------- pager */
  .pager {
    display: grid;
    grid-template-columns: 1fr;
    gap: 10px;
    margin-top: 36px;
  }
  @media (min-width: 560px) {
    .pager { grid-template-columns: 1fr 1fr; }
  }
  .pager a {
    display: block;
    min-height: 44px;
    border: 1px solid var(--line);
    background: var(--surface);
    border-radius: var(--radius);
    padding: 12px 15px;
    text-decoration: none;
    color: var(--ink);
    box-shadow: var(--shadow);
  }
  .pager a:hover { border-color: var(--ptr); }
  .pager a small {
    display: block;
    font-family: var(--mono);
    font-size: 11px;
    letter-spacing: .08em;
    text-transform: uppercase;
    color: var(--muted);
    margin-bottom: 3px;
  }
  .pager a.next { text-align: right; }

  footer {
    margin-top: 40px;
    color: var(--muted);
    font-size: 14px;
    border-top: 1px solid var(--line);
    padding-top: 16px;
    max-width: 68ch;
  }

  /* ----------------------------------------------------------- index page */
  .topic-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 12px;
    margin: 18px 0 8px;
  }
  @media (min-width: 560px) { .topic-grid { grid-template-columns: repeat(2, 1fr); } }
  @media (min-width: 1024px) { .topic-grid { grid-template-columns: repeat(3, 1fr); } }

  .topic-slot { position: relative; display: grid; }
  .topic-card {
    display: block;
    height: 100%;
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 36px 16px 15px;
    text-decoration: none;
    color: var(--ink);
    box-shadow: var(--shadow);
  }
  .topic-card:hover { border-color: var(--ptr); }
  .topic-card .n {
    font-family: var(--mono);
    font-size: 11.5px;
    font-weight: 600;
    color: var(--ptr);
    letter-spacing: .07em;
  }
  .topic-card h3 { margin: 5px 0 6px; font-size: 19px; }
  .topic-card p { margin: 0; font-size: 14px; color: var(--muted); max-width: none; }
  .topic-card .lessons {
    margin-top: 9px;
    font-size: 11.5px;
    line-height: 1.5;
    color: var(--muted);
    font-family: var(--mono);
  }
  .done-box {
    position: absolute;
    top: 6px;
    right: 8px;
    z-index: 2;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    min-height: 34px;
    padding: 0 6px;
    font-family: var(--mono);
    font-size: 11px;
    font-weight: 600;
    letter-spacing: .08em;
    text-transform: uppercase;
    color: var(--muted);
    cursor: pointer;
    -webkit-user-select: none;
    user-select: none;
  }
  .done-box input {
    width: 17px;
    height: 17px;
    margin: 0;
    accent-color: var(--ptr);
    cursor: pointer;
  }
  .done-box:hover, .done-box:focus-within { color: var(--ptr); }
  .topic-slot.is-done .topic-card { border-color: var(--ptr); }
  .topic-slot.is-done .done-box { color: var(--ptr); }
  .done-count {
    font-family: var(--mono);
    font-size: 12px;
    font-weight: 600;
    letter-spacing: .08em;
    text-transform: uppercase;
    color: var(--ptr);
    margin: 2px 0 12px;
  }
  .roadmap { margin: 20px 0; }

  @media (prefers-reduced-motion: no-preference) {
    html { scroll-behavior: smooth; }
  }