/* Zero Theta — "Proof" design system (shared) */

:root{
  --paper:#FBFAF7;
  --ink:#14120F;
  --oxblood:#7A1F2B;
  --grid:#DCE4EE;
  --gray:#6B675F;
  --hairline:rgba(20,18,15,.28);
  --serif:"STIX Two Text", "Times New Roman", serif;
  --sans:"Public Sans", "Helvetica Neue", Arial, sans-serif;
}

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

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

body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--sans);
  font-size:1rem;
  line-height:1.65;
  font-weight:400;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

a{ color:var(--oxblood); text-decoration:underline; text-decoration-thickness:1px; text-underline-offset:2px; }
a:hover{ text-decoration-thickness:2px; }

:focus-visible{
  outline:2px solid var(--oxblood);
  outline-offset:2px;
  border-radius:1px;
}

.skip-link{
  position:absolute; left:-999px; top:0;
  background:var(--ink); color:var(--paper);
  padding:.5rem 1rem; z-index:10; font-size:.85rem;
  text-decoration:none;
}
.skip-link:focus{ left:1rem; top:1rem; }

/* ---------- Masthead ---------- */
header.masthead{
  border-bottom:1px solid var(--hairline);
}
.masthead-inner{
  max-width:calc(68ch + 302px);
  margin:0 auto;
  padding:1.1rem 24px 1rem;
  display:flex;
  flex-wrap:wrap;
  align-items:baseline;
  justify-content:space-between;
  gap:.6rem 2rem;
}
.wordmark{
  margin:0;
  font-family:var(--sans);
  font-size:.8rem;
  letter-spacing:.14em;
  text-transform:uppercase;
  white-space:nowrap;
}
.wordmark a{
  color:var(--ink);
  text-decoration:none;
  display:flex;
  align-items:baseline;
  gap:.65rem;
}
.wordmark a:hover .co{ color:var(--oxblood); }
.theta-mark{
  position:relative;
  display:inline-block;
  font-family:var(--serif);
  font-style:italic;
  font-size:1.35rem;
  line-height:1;
  letter-spacing:0;
  transform:translateY(.12em);
  color:var(--ink);
}
.theta-mark::after{
  content:"";
  position:absolute;
  left:-14%;
  right:-14%;
  top:52%;
  height:1.5px;
  background:var(--oxblood);
  transform:rotate(-14deg);
  pointer-events:none;
}
.wordmark .co{ font-weight:500; }

nav.paper-nav ul{
  list-style:none;
  margin:0; padding:0;
  display:flex;
  gap:1.6rem;
}
nav.paper-nav a{
  font-family:var(--sans);
  font-size:.78rem;
  letter-spacing:.12em;
  text-transform:uppercase;
  color:var(--ink);
  text-decoration:none;
}
nav.paper-nav a:hover{ color:var(--oxblood); text-decoration:underline; text-decoration-thickness:1px; text-underline-offset:4px; }
nav.paper-nav a[aria-current="page"]{
  color:var(--oxblood);
  text-decoration:underline;
  text-decoration-thickness:1.5px;
  text-underline-offset:4px;
}

/* ---------- Page frame: article column + wide right margin ---------- */
.wrap{
  max-width:calc(68ch + 302px);
  margin:0 auto;
  padding:0 24px;
}
.article{
  max-width:68ch;
}

/* Margin notes (Tufte-style float on wide screens) */
.mnote{
  float:right;
  clear:right;
  width:232px;
  margin-right:-278px;
  margin-top:.15rem;
  margin-bottom:1.2rem;
  font-size:.76rem;
  line-height:1.55;
  color:var(--gray);
}
.mnote .mnote-mark{
  color:var(--oxblood);
  font-family:var(--serif);
}

/* ---------- Title block ---------- */
.titleblock{
  text-align:center;
  padding-top:3.4rem;
}
.titleblock h1{
  font-family:var(--serif);
  font-weight:500;
  font-size:clamp(1.7rem, 4.6vw, 2.75rem);
  line-height:1.22;
  margin:0 auto .4rem;
  max-width:26ch;
  letter-spacing:.005em;
}
.titleblock h1 .subtitle{
  display:block;
  font-size:.62em;
  font-weight:400;
  font-style:italic;
  margin-top:.55rem;
  color:var(--ink);
}
.authors{
  font-family:var(--serif);
  font-size:1rem;
  margin:1.4rem 0 0;
  color:var(--ink);
}
.authors .affil{
  display:block;
  font-size:.82rem;
  font-family:var(--sans);
  color:var(--gray);
  margin-top:.25rem;
  letter-spacing:.02em;
}

/* ---------- Figures ---------- */
figure{
  margin:2.6rem 0;
}
figure.hero-fig{
  margin-top:2.9rem;
}
figure svg{
  display:block;
  width:100%;
  height:auto;
}
/* flow / block diagrams stay legible on narrow screens by scrolling */
.fig-flow .fig-scroll{ overflow-x:auto; }
.fig-flow .fig-scroll:focus-visible{ outline:2px solid var(--oxblood); outline-offset:3px; }
.fig-flow svg{ min-width:560px; }
figcaption{
  font-family:var(--sans);
  font-size:.78rem;
  color:var(--gray);
  margin-top:.7rem;
  line-height:1.5;
}
figcaption .fig-label{
  color:var(--ink);
  font-weight:600;
  letter-spacing:.02em;
}
.hero-fig figcaption{ text-align:center; }

/* ---------- Abstract ---------- */
.abstract{
  margin:3rem auto 0;
  max-width:56ch;
}
.abstract h2{
  font-family:var(--serif);
  font-style:italic;
  font-weight:500;
  font-size:1.05rem;
  text-align:center;
  margin:0 0 .8rem;
}
.abstract p{
  font-size:.92rem;
  line-height:1.7;
  text-align:justify;
  hyphens:auto;
  margin:0;
}
.abstract p::first-letter{ padding-left:1.4em; }
.keywords{
  max-width:66ch;
  margin:1.4rem auto 0;
  font-size:.78rem;
  color:var(--gray);
  line-height:1.6;
}
.keywords .kw-label{
  font-family:var(--serif);
  font-style:italic;
  color:var(--ink);
}

/* ---------- Sections ---------- */
main{ padding-bottom:1rem; }
section.paper-section{
  margin-top:4.2rem;
}
section.paper-section h2{
  font-family:var(--serif);
  font-weight:600;
  font-size:1.45rem;
  line-height:1.3;
  margin:0 0 1.1rem;
}
section.paper-section h2 .secnum{
  display:inline-block;
  min-width:2.2rem;
  font-weight:500;
}
p{ margin:0 0 1.1rem; }
.article > section p, .article section p{ max-width:68ch; }

var, .mvar{
  font-family:var(--serif);
  font-style:italic;
  font-size:1.06em;
}
.math{
  font-family:var(--serif);
  font-style:italic;
  white-space:nowrap;
  font-size:1.06em;
}
.math .upright{ font-style:normal; }

sup.fnref{
  line-height:0;
  font-size:.72em;
}
sup.fnref a{ text-decoration:none; }
sup.fnref a:hover{ text-decoration:underline; }

/* ---------- Definitions, propositions, remarks, examples ---------- */
.definition{
  margin:0 0 1.15rem;
}
.definition .def-head{
  font-family:var(--serif);
  font-style:normal;
  font-weight:600;
  font-size:1.02rem;
}
.definition .def-name{
  font-weight:400;
  font-style:italic;
}
.proposition{
  font-style:italic;
}
.proposition .def-head, .proposition .def-name{ font-style:normal; }
.proposition .def-name{ font-style:italic; }
.example{ margin-bottom:1.6rem; }

/* ---------- Paper-style cross references ---------- */
.continue{
  font-size:.84rem;
  color:var(--gray);
}
.continue a, a.xref{
  font-family:var(--sans);
  text-decoration:none;
  color:var(--oxblood);
  letter-spacing:.01em;
}
.continue a:hover, a.xref:hover{
  text-decoration:underline;
  text-decoration-thickness:1px;
  text-underline-offset:3px;
}

/* ---------- Algorithm block ---------- */
.algorithm{
  margin:2.2rem 0;
  border-top:2px solid var(--ink);
  border-bottom:1px solid var(--ink);
  padding:.65rem 0 .9rem;
}
.algorithm .alg-title{
  font-family:var(--sans);
  font-size:.85rem;
  font-weight:600;
  letter-spacing:.01em;
  padding-bottom:.55rem;
  border-bottom:1px solid var(--hairline);
  margin-bottom:.75rem;
}
.algorithm .alg-title .alg-label{ font-weight:600; }
.algorithm .alg-title .alg-name{ font-weight:400; font-style:italic; font-family:var(--serif); font-size:1.02em; }
.algorithm ol{
  margin:0;
  padding-left:2.1rem;
  font-size:.86rem;
  line-height:1.75;
  counter-reset:algline;
  list-style:none;
}
.algorithm ol li{
  counter-increment:algline;
  position:relative;
}
.algorithm ol li::before{
  content:counter(algline);
  position:absolute;
  left:-2.1rem;
  width:1.4rem;
  text-align:right;
  color:var(--gray);
  font-size:.78em;
  top:.18em;
}
.algorithm .kw{
  font-weight:600;
  font-size:.94em;
  letter-spacing:.01em;
}
.algorithm .cm{
  color:var(--gray);
  font-style:italic;
}

/* ---------- Author biography block ---------- */
.bio{
  margin:1.9rem 0;
  padding:1.05rem 1.25rem .95rem;
  border-top:2px solid var(--ink);
  border-bottom:1px solid var(--ink);
  font-size:.9rem;
  line-height:1.7;
}
.bio .bio-label{
  display:block;
  font-family:var(--sans);
  font-size:.72rem;
  letter-spacing:.14em;
  text-transform:uppercase;
  color:var(--gray);
  margin-bottom:.4rem;
}
.bio p{ margin:0; }

/* ---------- Contact ---------- */
.contact-block{
  font-family:var(--serif);
  font-size:1.05rem;
  margin-top:1.6rem;
}
.contact-block .contact-label{
  font-family:var(--sans);
  font-size:.72rem;
  letter-spacing:.14em;
  text-transform:uppercase;
  color:var(--gray);
  display:block;
  margin-bottom:.3rem;
}
.contact-block.contact-xl{
  font-size:clamp(1.35rem, 4vw, 2.1rem);
  line-height:1.35;
  margin-top:2rem;
}
.contact-block.contact-xl a{
  text-decoration-thickness:1.5px;
  text-underline-offset:5px;
  overflow-wrap:anywhere;
}

/* ---------- Footnotes ---------- */
.footnotes{
  margin-top:4.5rem;
  padding-bottom:1rem;
}
.footnotes::before{
  content:"";
  display:block;
  width:132px;
  border-top:1px solid var(--hairline);
  margin-bottom:1.1rem;
}
.footnotes h2{
  position:absolute;
  width:1px; height:1px;
  overflow:hidden;
  clip:rect(0 0 0 0);
  white-space:nowrap;
}
.footnotes ol{
  margin:0;
  padding-left:1.3rem;
  font-size:.79rem;
  line-height:1.6;
  color:var(--ink);
}
.footnotes li{ margin-bottom:.55rem; }
.footnotes li:target{ background:rgba(220,228,238,.55); }
.fn-back{ text-decoration:none; font-size:.9em; }

/* ---------- Footer ---------- */
footer.colophon{
  border-top:1px solid var(--hairline);
  margin-top:1.5rem;
}
.colophon-inner{
  max-width:calc(68ch + 302px);
  margin:0 auto;
  padding:1.3rem 24px 2.6rem;
  display:flex;
  flex-wrap:wrap;
  justify-content:space-between;
  gap:.5rem 2rem;
  font-size:.78rem;
  color:var(--gray);
}

/* ---------- Responsive ---------- */
@media (max-width:1149px){
  .masthead-inner, .colophon-inner, .wrap{ max-width:calc(68ch + 48px); }
  .mnote{
    float:none;
    clear:none;
    width:auto;
    margin:1.3rem 0 1.5rem;
    padding:.55rem .95rem;
    border-left:2px solid var(--grid);
  }
}
@media (max-width:640px){
  .masthead-inner{ padding-top:.9rem; padding-bottom:.85rem; }
  .wordmark{ white-space:normal; }
  nav.paper-nav ul{ gap:1.1rem; flex-wrap:wrap; }
  .titleblock{ padding-top:2.4rem; }
  .abstract p{ text-align:left; hyphens:none; }
  .algorithm ol{ padding-left:1.7rem; }
  .algorithm ol li::before{ left:-1.7rem; }
  .bio{ padding:.9rem .95rem .8rem; }
}