/* ============================================================
   INVERTED PENDULUM & PID CONTROL — research paper page
   Extends the site design system (styles.css tokens).
   Author: Giorgi Suramlishvili
   ============================================================ */

:root {
  --pp-read: 720px;            /* comfortable reading measure */
  --pp-pole: var(--ink);
  --pp-stroke: var(--ink-2);
  --pp-dim: var(--ink-3);
  --pp-faint: var(--rule);
  --pp-grid: var(--rule-2);
  --pp-good: #1f9d63;          /* stable / left-half-plane */
  --pp-bad: var(--signal);     /* unstable / right-half-plane */
}
html[data-theme="dark"] {
  --pp-good: #34d399;
}

/* ------------------------------------------------------------
   HERO
   ------------------------------------------------------------ */
.paper-hero { padding: 60px 0 52px; }
.paper-hero .coord b { color: var(--signal); }

.paper-hero-grid {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 52px;
  align-items: center;
}
@media (max-width: 900px) {
  .paper-hero-grid { grid-template-columns: 1fr; gap: 36px; }
}

.tag-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 18px 0 26px; }
.paper-tag {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-2);
  border: 1px solid var(--rule);
  background: var(--paper-2);
  padding: 5px 10px;
  border-radius: 2px;
  font-weight: 500;
}
.paper-tag.signal { color: var(--paper); background: var(--signal); border-color: var(--signal); }

.detail-title .amp { color: var(--signal); font-style: normal; }

.paper-lede {
  font-size: 17px;
  line-height: 1.65;
  color: var(--ink-2);
  max-width: 60ch;
  margin-top: 6px;
}
.paper-lede strong { color: var(--ink); font-weight: 600; }

.paper-hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 34px; }

.byline {
  margin-top: 30px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 22px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.05em;
  color: var(--ink-3);
}
.byline b { color: var(--ink); font-weight: 500; }

/* hero figure frame */
.hero-figure {
  position: relative;
  border: 1px solid var(--rule);
  background:
    linear-gradient(var(--pp-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--pp-grid) 1px, transparent 1px),
    var(--paper-2);
  background-size: 22px 22px, 22px 22px, auto;
  background-position: center;
  border-radius: 4px;
  overflow: hidden;
  aspect-ratio: 1 / 1;
  box-shadow: 6px 6px 0 color-mix(in oklab, var(--ink) 7%, transparent);
}
.hero-figure .fig-tag {
  position: absolute;
  top: 12px; left: 12px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-3);
  z-index: 2;
}
.hero-figure .fig-readout {
  position: absolute;
  bottom: 12px; right: 14px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.08em;
  color: var(--ink-3);
  text-align: right;
  z-index: 2;
}
.hero-figure .fig-readout b { color: var(--signal); font-weight: 600; }
.hero-figure svg { display: block; width: 100%; height: 100%; }

/* ------------------------------------------------------------
   PAPER LAYOUT — sticky TOC + article column
   ------------------------------------------------------------ */
.paper-layout {
  display: grid;
  grid-template-columns: 232px minmax(0, 1fr);
  gap: 56px;
  padding: 56px 0 24px;
  align-items: start;
}
@media (max-width: 940px) {
  .paper-layout {
    grid-template-columns: minmax(0, 1fr);
    gap: 8px;
    min-width: 0;
  }
  .paper-layout > * {
    min-width: 0;
  }
}

.paper-toc {
  position: sticky;
  top: 84px;
  align-self: start;
}
@media (max-width: 940px) {
  .paper-toc {
    position: static;
    width: 100%;
    max-width: 100%;
    min-width: 0;
    border: 1px solid var(--rule);
    background: var(--paper-2);
    border-radius: 4px;
    margin-bottom: 28px;
    overflow: hidden;
  }
  .paper-toc-inner {
    width: 100%;
    max-width: 100%;
    min-width: 0;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease;
  }
  .paper-toc.open .paper-toc-inner { max-height: 1400px; }
  .toc-mobile-btn { display: flex; }
}
.toc-mobile-btn {
  display: none;
  width: 100%;
  align-items: center;
  justify-content: space-between;
  background: none;
  border: 0;
  padding: 16px 18px;
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink);
  font-weight: 500;
}
.toc-mobile-btn .chev { transition: transform 0.3s ease; color: var(--signal); }
.paper-toc.open .toc-mobile-btn .chev { transform: rotate(180deg); }

.toc-label {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-3);
  display: flex; align-items: center; gap: 9px;
  margin: 0 0 16px;
}
.toc-label::before { content: ""; width: 22px; height: 1px; background: var(--signal); }
@media (max-width: 940px) {
  .toc-label { display: none; }
  .toc-mobile-btn { display: flex; }
  .paper-toc-inner { padding: 0 18px; }
  .paper-toc.open .paper-toc-inner { padding-bottom: 18px; }
}

.toc-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.toc-list li { min-width: 0; }
.toc-link {
  display: flex;
  gap: 10px;
  align-items: baseline;
  width: 100%;
  min-width: 0;
  padding: 6px 10px 6px 0;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.4;
  color: var(--ink-3);
  border-left: 2px solid transparent;
  padding-left: 12px;
  transition: color 0.18s ease, border-color 0.18s ease, background 0.18s ease;
}
.toc-link span:last-child { min-width: 0; overflow-wrap: anywhere; }
.toc-link .tn { color: var(--ink-4); font-size: 10.5px; min-width: 18px; }
.toc-link:hover { color: var(--ink); border-left-color: var(--rule); }
.toc-link.active { color: var(--signal); border-left-color: var(--signal); font-weight: 500; }
.toc-link.active .tn { color: var(--signal); }

/* reading-progress for the article (uses the global .scroll-progress instead;
   this is a slim per-section indicator) */
.read-meta {
  margin-top: 26px;
  padding-top: 18px;
  border-top: 1px solid var(--rule);
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.05em;
  color: var(--ink-3);
  line-height: 1.8;
}
.read-meta b { color: var(--ink); font-weight: 500; }
@media (max-width: 940px) { .read-meta { display: none; } }

@media (max-width: 940px) {
  .paper-article {
    width: 100%;
    max-width: 100%;
    min-width: 0;
  }
}

/* ------------------------------------------------------------
   ARTICLE
   ------------------------------------------------------------ */
.paper-article { max-width: var(--pp-read); }

.psec { padding: 14px 0 30px; scroll-margin-top: 80px; }
.psec + .psec { border-top: 1px solid var(--rule); padding-top: 40px; }

.psec-kicker {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--signal);
  display: flex; align-items: center; gap: 10px;
  font-weight: 500;
  margin-bottom: 14px;
}
.psec-kicker::before { content: ""; width: 26px; height: 1px; background: var(--signal); }

.psec-title {
  font-family: var(--font-display);
  font-size: clamp(26px, 3.4vw, 38px);
  letter-spacing: -0.025em;
  line-height: 1.06;
  font-weight: 500;
  color: var(--ink);
  margin: 0 0 22px;
  display: flex; gap: 16px; align-items: baseline;
}
.psec-title .psec-num {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--ink-4);
  font-weight: 500;
  letter-spacing: 0.04em;
  flex: none;
  padding-top: 6px;
}

.psec h3 {
  font-family: var(--font-display);
  font-size: 19px;
  letter-spacing: -0.015em;
  font-weight: 600;
  color: var(--ink);
  margin: 34px 0 14px;
}
.psec h3 .h3-mark { color: var(--signal); margin-right: 8px; font-weight: 500; }

.paper-article p {
  font-size: 15.5px;
  line-height: 1.78;
  color: var(--ink-2);
  margin: 0 0 16px;
  max-width: 66ch;
}
.paper-article p strong { color: var(--ink); font-weight: 600; }
.paper-article a.inl { color: var(--signal); border-bottom: 1px solid color-mix(in oklab, var(--signal) 35%, transparent); }
.paper-article a.inl:hover { border-bottom-color: var(--signal); }

.lead {
  font-size: 18px !important;
  line-height: 1.7 !important;
  color: var(--ink) !important;
  font-family: var(--font-display);
  letter-spacing: -0.01em;
  max-width: 64ch;
}
.lead .drop {
  float: left;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 58px;
  line-height: 0.82;
  padding: 6px 12px 0 0;
  color: var(--signal);
}

.paper-article ul.pp-bullets { list-style: none; margin: 4px 0 20px; padding: 0; display: flex; flex-direction: column; gap: 11px; }
.paper-article ul.pp-bullets li {
  position: relative;
  padding-left: 26px;
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--ink-2);
}
.paper-article ul.pp-bullets li::before {
  content: "→";
  position: absolute; left: 0; top: 0;
  color: var(--signal);
  font-family: var(--font-mono);
}
.paper-article ul.pp-bullets li b { color: var(--ink); font-weight: 600; }

/* ------------------------------------------------------------
   EQUATIONS
   ------------------------------------------------------------ */
.eq {
  position: relative;
  margin: 22px 0;
  padding: 18px 56px 18px 22px;
  border: 1px solid var(--rule);
  border-left: 2px solid var(--signal);
  background: var(--paper-2);
  border-radius: 3px;
  overflow-x: auto;
  overflow-y: hidden;
}
.eq.center { text-align: center; }
.eq .katex-display { margin: 0; }
.eq .katex { font-size: 1.12em; }
.eq-num {
  position: absolute;
  top: 50%; right: 16px;
  transform: translateY(-50%);
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-3);
}
.eq-note {
  font-family: var(--font-mono);
  font-size: 11.5px;
  color: var(--ink-3);
  margin: -6px 0 18px;
  letter-spacing: 0.02em;
}
/* inline math sizing */
.paper-article .katex { font-size: 1.04em; }

/* a compact inline equation chip used mid-sentence */
.eq-chip {
  display: inline-block;
  background: var(--paper-3);
  border: 1px solid var(--rule);
  border-radius: 3px;
  padding: 1px 7px;
  margin: 0 1px;
}

/* ------------------------------------------------------------
   VARIABLE GLOSSARY
   ------------------------------------------------------------ */
.vardefs {
  margin: 20px 0 24px;
  border: 1px solid var(--rule);
  border-radius: 4px;
  overflow: hidden;
  background: var(--paper-2);
}
.vardefs-head {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-3);
  padding: 11px 16px;
  border-bottom: 1px solid var(--rule);
  background: var(--paper-3);
}
.vardef {
  display: grid;
  grid-template-columns: 78px 1fr;
  gap: 16px;
  padding: 13px 16px;
  align-items: start;
}
.vardef + .vardef { border-top: 1px solid var(--rule); }
.vardef .sym { text-align: center; padding-top: 2px; color: var(--ink); }
.vardef .sym .katex { font-size: 1.15em; }
.vardef .def { font-size: 13.5px; line-height: 1.6; color: var(--ink-2); }
.vardef .def b { color: var(--ink); font-weight: 600; }

/* ------------------------------------------------------------
   CALLOUTS / NOTES
   ------------------------------------------------------------ */
.note {
  position: relative;
  margin: 24px 0;
  padding: 18px 20px 18px 52px;
  border: 1px solid var(--rule);
  border-radius: 4px;
  background: var(--paper-2);
}
.note::before {
  content: "i";
  position: absolute;
  left: 16px; top: 18px;
  width: 22px; height: 22px;
  display: grid; place-items: center;
  border-radius: 50%;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 13px;
  color: var(--paper);
  background: var(--ink-3);
}
.note .note-label {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-3);
  font-weight: 500;
  margin-bottom: 6px;
  display: block;
}
.note p { margin: 0; font-size: 14px !important; line-height: 1.68 !important; }
.note.warn { border-left: 2px solid var(--signal); }
.note.warn::before { content: "!"; background: var(--signal); }
.note.warn .note-label { color: var(--signal); }
.note.tip { border-left: 2px solid var(--pp-good); }
.note.tip::before { content: "✓"; background: var(--pp-good); font-size: 12px; }
.note.tip .note-label { color: var(--pp-good); }

/* ------------------------------------------------------------
   FIGURES (animated SVG diagrams)
   ------------------------------------------------------------ */
.figbox {
  margin: 30px 0 16px;
  border: 1px solid var(--rule);
  border-radius: 4px;
  background:
    linear-gradient(var(--pp-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--pp-grid) 1px, transparent 1px),
    var(--paper-2);
  background-size: 22px 22px, 22px 22px, auto;
  position: relative;
  overflow: hidden;
}
.figbox .fig-head {
  display: flex; justify-content: space-between; align-items: center;
  padding: 12px 16px;
  border-bottom: 1px solid var(--rule);
  background: color-mix(in oklab, var(--paper-3) 70%, transparent);
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-3);
}
.figbox .fig-head .fig-id { color: var(--signal); font-weight: 600; }
.figbox .fig-stage { padding: 22px 18px; display: grid; place-items: center; }
.figbox svg { display: block; width: 100%; height: auto; max-width: 100%; }
.figcap {
  font-family: var(--font-mono);
  font-size: 11.5px;
  color: var(--ink-3);
  line-height: 1.6;
  margin: 0 0 26px;
  letter-spacing: 0.01em;
}
.figcap b { color: var(--ink); font-weight: 500; }

/* shared diagram primitives */
.d-stroke { stroke: var(--pp-stroke); fill: none; }
.d-dim { stroke: var(--pp-dim); fill: none; }
.d-faint { stroke: var(--pp-faint); fill: none; }
.d-pole { stroke: var(--pp-pole); fill: none; }
.d-accent { stroke: var(--signal); fill: none; }
.d-fill-accent { fill: var(--signal); }
.d-fill-ink { fill: var(--ink); }
.d-fill-paper { fill: var(--paper); }
.d-good { stroke: var(--pp-good); fill: none; }
.d-fill-good { fill: var(--pp-good); }
.d-label { font-family: var(--font-mono); font-size: 11px; fill: var(--ink-2); letter-spacing: 0.04em; }
.d-label-sm { font-family: var(--font-mono); font-size: 9.5px; fill: var(--ink-3); letter-spacing: 0.05em; }
.d-label-accent { fill: var(--signal); }
.d-label-good { fill: var(--pp-good); }

/* ---- animations ---- */
@keyframes pp-dash { to { stroke-dashoffset: -28; } }
@keyframes pp-draw { to { stroke-dashoffset: 0; } }
@keyframes pp-pulse-dot { 0%,100% { opacity: 0.3; } 50% { opacity: 1; } }
@keyframes pp-fade-rise { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }
@keyframes pp-orbit { to { offset-distance: 100%; } }

/* hero free-body: tasteful, physics-safe idle motion (geometry stays put) */
@keyframes pp-stage-in { from { opacity: 0; transform: scale(0.965); } to { opacity: 1; transform: scale(1); } }
@keyframes pp-glow { 0%,100% { opacity: 0.12; transform: scale(0.9); } 50% { opacity: 0.34; transform: scale(1.14); } }
@keyframes pp-correct { 0%,100% { opacity: 0.6; transform: translateX(2px); } 50% { opacity: 1; transform: translateX(-1.5px); } }
@keyframes pp-disturb { 0%,100% { opacity: 0.45; transform: translateX(0); } 50% { opacity: 0.9; transform: translateX(-4px); } }

.hero-figure .pp-stage { transform-box: fill-box; transform-origin: center; animation: pp-stage-in 1s cubic-bezier(0.16,1,0.3,1) both; }
.pp-glow { opacity: 0.18; transform-box: fill-box; transform-origin: center; animation: pp-glow 3.6s ease-in-out infinite; }
.pp-correct { transform-box: fill-box; transform-origin: center; animation: pp-correct 3.2s ease-in-out infinite; }
.pp-disturb { transform-box: fill-box; transform-origin: center; animation: pp-disturb 4.4s ease-in-out infinite; }

/* marching signal flow */
.pp-flow { stroke-dasharray: 6 8; animation: pp-dash 1.1s linear infinite; }

/* draw-in strokes (triggered when figure has .in) */
.pp-drawable { stroke-dasharray: var(--len, 1200); stroke-dashoffset: var(--len, 1200); }
.figbox.in .pp-drawable { animation: pp-draw 1.5s cubic-bezier(0.7,0,0.3,1) forwards; }
.figbox.in .pp-drawable.d2 { animation-delay: 0.4s; }
.figbox.in .pp-drawable.d3 { animation-delay: 0.8s; }

/* loop pulse dot travelling along a path */
.pp-loop-dot { fill: var(--signal); offset-path: var(--op); animation: pp-orbit 4s linear infinite; }

/* s-plane poles flying in */
.pp-pole-pt { opacity: 0; }
.figbox.in .pp-pole-pt { animation: pp-fade-rise 0.7s ease forwards; }
.figbox.in .pp-pole-pt.p2 { animation-delay: 0.18s; }
.figbox.in .pp-pole-pt.p3 { animation-delay: 0.36s; }
.figbox.in .pp-pole-pt.p4 { animation-delay: 0.54s; }
.pp-pulse { animation: pp-pulse-dot 2s ease-in-out infinite; }

/* PID response sparklines draw */
.pp-trace { stroke-dasharray: var(--len, 1200); stroke-dashoffset: var(--len, 1200); }
.figbox.in .pp-trace { animation: pp-draw 1.8s ease forwards; }
.figbox.in .pp-trace.t2 { animation-delay: 0.5s; }
.figbox.in .pp-trace.t3 { animation-delay: 1s; }

/* ------------------------------------------------------------
   MATRIX / NUMERIC SHOWCASE
   ------------------------------------------------------------ */
.matrix-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin: 22px 0;
}
@media (max-width: 620px) { .matrix-grid { grid-template-columns: 1fr; } }
.matrix-card {
  border: 1px solid var(--rule);
  background: var(--paper-2);
  border-radius: 4px;
  padding: 20px 18px;
  display: grid;
  place-items: center;
  position: relative;
}
.matrix-card .mc-tag {
  position: absolute; top: 10px; left: 12px;
  font-family: var(--font-mono);
  font-size: 9.5px; letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--ink-3);
}
.matrix-card .katex { font-size: 1.15em; }

/* ------------------------------------------------------------
   KEY RESULTS
   ------------------------------------------------------------ */
.keyresults {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  border: 1px solid var(--rule);
  border-radius: 4px;
  overflow: hidden;
  margin: 8px 0 30px;
}
@media (max-width: 760px) { .keyresults { grid-template-columns: repeat(2, 1fr); } }
.kr {
  padding: 20px 18px;
  border-right: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  background: var(--paper-2);
}
.kr .kr-k { font-family: var(--font-mono); font-size: 10px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 10px; }
.kr .kr-v { font-family: var(--font-display); font-size: 26px; letter-spacing: -0.02em; color: var(--ink); font-weight: 600; line-height: 1; }
.kr .kr-v .u { font-size: 13px; color: var(--ink-3); font-weight: 500; }
.kr .kr-sub { font-family: var(--font-mono); font-size: 10.5px; color: var(--ink-3); margin-top: 8px; line-height: 1.5; }

/* ------------------------------------------------------------
   WORKED-EXAMPLE STEPS
   ------------------------------------------------------------ */
.steps { counter-reset: step; margin: 18px 0 8px; }
.step {
  position: relative;
  padding: 0 0 30px 56px;
  border-left: 1px solid var(--rule);
  margin-left: 16px;
}
.step:last-child { border-left-color: transparent; padding-bottom: 4px; }
.step::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: -16px; top: -4px;
  width: 32px; height: 32px;
  border-radius: 50%;
  background: var(--paper);
  border: 1px solid var(--signal);
  color: var(--signal);
  display: grid; place-items: center;
  font-family: var(--font-mono);
  font-size: 13px; font-weight: 600;
}
.step h4 {
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--ink);
  margin: 2px 0 10px;
}
.step p { font-size: 14.5px !important; }

/* ------------------------------------------------------------
   PARAMETER TABLE
   ------------------------------------------------------------ */
.ptable-wrap { margin: 20px 0 24px; border: 1px solid var(--rule); border-radius: 4px; overflow: hidden; }
.ptable { width: 100%; border-collapse: collapse; font-family: var(--font-mono); }
.ptable th {
  text-align: left;
  font-size: 10px; letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--ink-3); font-weight: 500;
  padding: 12px 16px;
  background: var(--paper-3);
  border-bottom: 1px solid var(--rule);
}
.ptable td { padding: 11px 16px; font-size: 13px; color: var(--ink-2); border-bottom: 1px solid var(--rule); }
.ptable tr:last-child td { border-bottom: 0; }
.ptable tr:hover td { background: var(--paper-2); }
.ptable td:first-child { color: var(--ink); }
.ptable .sym { color: var(--signal); }
.ptable td .katex { font-size: 1em; }

/* ------------------------------------------------------------
   CODE CARD
   ------------------------------------------------------------ */
.codecard {
  margin: 20px 0 24px;
  border: 1px solid var(--rule);
  border-radius: 4px;
  overflow: hidden;
  background: var(--paper-2);
}
.codecard .cc-head {
  display: flex; align-items: center; gap: 8px;
  padding: 10px 14px;
  border-bottom: 1px solid var(--rule);
  background: var(--paper-3);
  font-family: var(--font-mono);
  font-size: 10px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-3);
}
.codecard .cc-dot { width: 9px; height: 9px; border-radius: 50%; background: var(--ink-4); }
.codecard .cc-dot.s { background: var(--signal); }
.codecard pre { margin: 0; padding: 16px 18px; overflow-x: auto; }
.codecard code {
  font-family: var(--font-mono);
  font-size: 12.5px;
  line-height: 1.7;
  color: var(--ink-2);
  white-space: pre;
}
.codecard code .kw { color: var(--signal); }
.codecard code .fn { color: var(--ink); font-weight: 600; }
.codecard code .cm { color: var(--ink-4); font-style: italic; }

/* ------------------------------------------------------------
   ORIGINAL SKETCH STRIP
   ------------------------------------------------------------ */
.sketch-strip {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 22px;
  align-items: center;
  margin: 26px 0;
  padding: 18px;
  border: 1px dashed var(--rule);
  border-radius: 4px;
  background: var(--paper-2);
}
@media (max-width: 620px) { .sketch-strip { grid-template-columns: 1fr; } }
.sketch-strip img {
  width: 100%; height: auto; display: block;
  border-radius: 3px;
  background: #fff;
  border: 1px solid var(--rule);
}
.sketch-strip .ss-text .label { margin-bottom: 8px; display: block; }
.sketch-strip .ss-text p { font-size: 13.5px !important; margin: 0; }

/* ------------------------------------------------------------
   CROSS-LINK TO ROBOT PROJECT
   ------------------------------------------------------------ */
.crosslink {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 14px 20px;
  margin: 36px 0 8px;
  padding: 20px 22px;
  border: 1px solid var(--rule);
  border-left: 3px solid var(--signal);
  border-radius: 4px;
  background: var(--paper-2);
  color: var(--ink);
  transition: transform 0.25s cubic-bezier(0.22,1,0.36,1), box-shadow 0.25s ease, border-color 0.25s ease, background-color 0.25s ease;
}
.crosslink:hover { transform: translate(-3px,-3px); box-shadow: 5px 5px 0 var(--signal); border-color: var(--signal); color: var(--ink); }
.crosslink .cl-icon { flex: none; width: 44px; height: 44px; color: var(--signal); }
.crosslink .cl-icon svg { width: 100%; height: 100%; }
.crosslink .cl-body { flex: 1 1 190px; }
.crosslink .cl-k { font-family: var(--font-mono); font-size: 10px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--signal); margin-bottom: 6px; }
.crosslink .cl-t { font-family: var(--font-display); font-size: 20px; font-weight: 600; letter-spacing: -0.015em; color: var(--ink); }
.crosslink .cl-status {
  flex: none;
  display: inline-flex; align-items: center; gap: 7px;
  font-family: var(--font-mono); font-size: 10px; font-weight: 500;
  letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--signal);
  background: var(--signal-soft);
  border: 1px solid color-mix(in oklab, var(--signal) 38%, transparent);
  padding: 6px 11px; border-radius: 999px;
  white-space: nowrap;
}
.crosslink .cl-dot { width: 6px; height: 6px; border-radius: 50%; background: var(--signal); animation: pp-pulse-dot 1.8s ease-in-out infinite; }
.crosslink .cl-arrow { flex: none; font-size: 22px; color: var(--signal); transition: transform 0.3s cubic-bezier(0.22,1,0.36,1); }
.crosslink:hover .cl-arrow { transform: translateX(8px); }

/* ------------------------------------------------------------
   PROJECT THUMBNAIL (homepage) — pendulum schematic accent
   handled in main styles via .thumb-schematic; nothing needed here.
   ------------------------------------------------------------ */

/* ------------------------------------------------------------
   REDUCED MOTION — freeze all motion, show final states
   ------------------------------------------------------------ */
@media (prefers-reduced-motion: reduce) {
  .pp-flow, .pp-loop-dot, .pp-pulse, .pp-glow, .pp-correct, .pp-disturb, .cl-dot { animation: none !important; }
  .hero-figure .pp-stage { animation: none !important; opacity: 1 !important; transform: none !important; }
  .pp-drawable, .pp-trace { stroke-dashoffset: 0 !important; animation: none !important; }
  .pp-pole-pt { opacity: 1 !important; animation: none !important; }
  .pp-glow { opacity: 0.22 !important; }
  .pp-correct { opacity: 1 !important; transform: none !important; }
}

/* ------------------------------------------------------------
   RESPONSIVE — tablet
   ------------------------------------------------------------ */
@media (max-width: 760px) {
  .matrix-card { overflow-x: auto; }
  .matrix-card .katex { font-size: 1.05em; }
}

/* ------------------------------------------------------------
   RESPONSIVE — phone: keep wide technical diagrams legible by
   letting them scroll horizontally instead of shrinking to dust
   ------------------------------------------------------------ */
@media (max-width: 640px) {
  .figbox .fig-stage {
    padding: 18px 14px;
    display: block;
    overflow-x: auto;
    overflow-y: hidden;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: thin;
  }
  .figbox .fig-stage > svg { min-width: 540px; margin: 0 auto; }
  /* the hero figure is square and scales fine — never force it to scroll */
  .hero-figure svg { min-width: 0; }
  .fig-scroll-hint { display: block; }
}

/* small screens: tighten hero + article */
@media (max-width: 560px) {
  .paper-hero { padding: 38px 0 34px; }
  .paper-hero-grid { gap: 30px; }
  .hero-figure { max-width: 340px; margin: 0 auto; width: 100%; }
  .eq { padding: 14px 16px; margin: 18px 0; }
  .eq-num { display: none; }
  .eq .katex { font-size: 1.02em; }
  .lead { font-size: 16.5px !important; }
  .lead .drop { font-size: 44px; }
  .step { padding-left: 42px; }
  .step::before { width: 28px; height: 28px; left: -14px; }
  .psec-title { gap: 12px; }
  .vardef { grid-template-columns: 60px 1fr; gap: 12px; }
  .keyresults { grid-template-columns: 1fr 1fr; }
  .byline { gap: 6px 16px; }
  .ptable th, .ptable td { padding: 10px 12px; font-size: 12px; }
}

/* very narrow */
@media (max-width: 380px) {
  .matrix-grid { gap: 12px; }
  .kr .kr-v { font-size: 22px; }
}