/* ==========================================================================
   Math Buddies blog — one stylesheet for /blog/ and every post.
   Shared by all blog pages so the section reads as part of mathbuddies.app,
   not a bolt-on. Tokens and masthead grammar mirror public/landing.html.
   No trackers, no fonts loaded from third parties, no shadows.
   ========================================================================== */

@font-face {
  font-family: 'Zilla Slab';
  src: url('/landing/fonts/ZillaSlab-Bold.ttf') format('truetype');
  font-weight: 700;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'Lexend';
  src: url('/landing/fonts/Lexend-Regular.ttf') format('truetype');
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'Lexend';
  src: url('/landing/fonts/Lexend-SemiBold.ttf') format('truetype');
  font-weight: 600;
  font-style: normal;
  font-display: swap;
}

:root {
  --paper: #F2F4EF;
  --paper-deep: #E7EBE2;
  --contour: #CBD6C6;
  --pine: #1B2A22;
  --pine-soft: #3A4B41;
  --pine-muted: #4F5D55;
  --bark-deep: #2A1F17;
  --cut: #F4EFE2;
  --blaze: #C2481B;
  --blaze-deep: #A63A0F;
  --forest: #2F6B4F;
  --ochre: #C9911B;
  --rule: 2px solid var(--pine);
  --page: 1120px;
  --measure: 700px;
  --display: 'Zilla Slab', 'Rockwell', 'Roboto Slab', Georgia, serif;
  --body: 'Lexend', 'Avenir Next', 'Segoe UI', system-ui, sans-serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

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

body {
  font-family: var(--body);
  font-size: 17px;
  line-height: 1.7;
  color: var(--pine-soft);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { max-width: 100%; display: block; }
a { color: inherit; }
::selection { background: #FAEFD3; color: var(--pine); }
:focus-visible { outline: 3px solid var(--blaze); outline-offset: 2px; }

.skip {
  position: absolute; left: -9999px; top: 0; z-index: 1000;
  background: var(--paper); color: var(--pine); padding: 10px 16px;
  border: var(--rule); font-weight: 600;
}
.skip:focus { left: 12px; top: 12px; }

.wrap { width: min(var(--page), calc(100% - 48px)); margin-inline: auto; }
@media (max-width: 640px) { .wrap { width: calc(100% - 32px); } }

.eyebrow {
  font-family: var(--body);
  font-weight: 600;
  font-size: 12px;
  letter-spacing: .16em;
  text-transform: uppercase;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

/* ------------------------------------------------------------- masthead */
.masthead { background: var(--bark-deep); color: var(--paper); position: relative; z-index: 10; }
.masthead-row {
  display: flex; align-items: center; justify-content: space-between;
  gap: 16px; padding: 14px 0;
}
.brand { display: inline-flex; align-items: center; gap: 12px; text-decoration: none; color: var(--paper); }
.brand img { width: 40px; height: 40px; border-radius: 8px; }
.brand-name { font-family: var(--display); font-weight: 700; font-size: 19px; line-height: 1.05; }
.brand-sub {
  display: block; font-weight: 600; font-size: 10px; letter-spacing: .22em;
  text-transform: uppercase; color: var(--ochre); margin-top: 3px;
}
.masthead nav { display: flex; align-items: center; gap: 22px; }
.masthead nav a.navlink {
  text-decoration: none; font-size: 14px; font-weight: 600; letter-spacing: .04em;
  color: #D8DFD4; border-bottom: 2px solid transparent; padding-bottom: 2px;
}
.masthead nav a.navlink:hover { color: #fff; border-bottom-color: var(--ochre); }
.masthead nav a.navlink[aria-current="page"] { color: #fff; border-bottom-color: var(--ochre); }
@media (max-width: 940px) { .masthead nav a.navlink { display: none; } }

.stripes { display: flex; height: 6px; }
.stripes i { flex: 1; }
.stripes i:nth-child(1) { background: var(--blaze); }
.stripes i:nth-child(2) { background: var(--ochre); }
.stripes i:nth-child(3) { background: var(--forest); }
.stripes i:nth-child(4) { background: #5C8FA8; }

/* -------------------------------------------------------------- buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 10px;
  font-family: var(--body); font-weight: 600; font-size: 16px; line-height: 1;
  text-decoration: none; padding: 15px 24px 14px; border-radius: 2px;
  border: 2px solid var(--pine); box-shadow: 0 3px 0 var(--pine);
  transition: transform .12s ease, box-shadow .12s ease, background-color .12s ease;
  cursor: pointer;
}
.btn:hover { transform: translateY(1px); box-shadow: 0 2px 0 var(--pine); }
.btn:active { transform: translateY(3px); box-shadow: 0 0 0 var(--pine); }
.btn-blaze { background: var(--blaze); border-color: var(--blaze-deep); box-shadow: 0 3px 0 var(--blaze-deep); color: #fff; }
.btn-blaze:hover { background: var(--blaze-deep); box-shadow: 0 2px 0 #8A2E09; }
.btn-ghost { background: transparent; color: var(--paper); border-color: #55665B; box-shadow: 0 3px 0 #55665B; }
.btn-ghost:hover { border-color: var(--paper); box-shadow: 0 2px 0 var(--paper); }
@media (prefers-reduced-motion: reduce) {
  .btn { transition: none; }
  .btn:hover, .btn:active { transform: none; }
}

/* ------------------------------------------------------- section headings */
.section-head { max-width: 660px; margin-bottom: 44px; }
.section-head .eyebrow { color: var(--blaze); }
.section-head h2 {
  font-family: var(--display); font-weight: 700;
  font-size: clamp(28px, 4vw, 42px); line-height: 1.08;
  letter-spacing: -0.01em; color: var(--pine); margin: 14px 0 14px;
}
.section-head p { color: var(--pine-muted); }

/* --------------------------------------------------------------- banners */
.blog-head {
  position: relative;
  background-color: var(--pine);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='480' height='480' viewBox='0 0 480 480'%3E%3Cg fill='none' stroke='%23F2F4EF' stroke-width='1.4' opacity='0.07'%3E%3Cpath d='M-30 90 C 60 40, 150 140, 250 100 S 420 30, 510 80'/%3E%3Cpath d='M-30 160 C 60 110, 160 210, 260 170 S 430 100, 510 150'/%3E%3Cpath d='M-30 230 C 70 180, 170 280, 270 240 S 440 170, 510 220'/%3E%3Cpath d='M-30 300 C 60 250, 160 350, 260 310 S 430 240, 510 290'/%3E%3Cpath d='M-30 370 C 70 320, 170 420, 270 380 S 440 310, 510 360'/%3E%3Cpath d='M-30 440 C 60 390, 160 490, 260 450 S 430 380, 510 430'/%3E%3C/g%3E%3C/svg%3E");
  color: var(--paper);
  border-bottom: 3px solid var(--bark-deep);
  padding: 64px 0 68px;
}
.blog-head .eyebrow { color: var(--ochre); }
.blog-head .eyebrow::before {
  content: ''; width: 26px; height: 4px; background: var(--blaze); display: inline-block;
}
.blog-head h1 {
  font-family: var(--display); font-weight: 700;
  font-size: clamp(38px, 6vw, 62px); line-height: 1.02;
  letter-spacing: -0.015em; color: #fff; margin: 18px 0 18px; max-width: 18ch;
}
.blog-head p { font-size: clamp(17px, 1.9vw, 20px); line-height: 1.6; color: #C9D3CB; max-width: 46ch; }

/* ------------------------------------------------------------ post index */
.posts { padding: 64px 0 72px; }
.post-list { list-style: none; border-top: var(--rule); }
.post-item { border-bottom: var(--rule); }
.post-link {
  display: grid; grid-template-columns: 152px 1fr; gap: 30px;
  padding: 30px 0 32px; text-decoration: none; align-items: start;
}
.post-link:hover .post-title { color: var(--blaze); }
.post-link:hover .post-more { border-bottom-color: var(--blaze); }
.post-when {
  font-size: 13px; font-weight: 600; letter-spacing: .1em; text-transform: uppercase;
  color: var(--pine-muted); padding-top: 7px;
}
.post-kicker {
  display: inline-block; font-size: 11.5px; font-weight: 600; letter-spacing: .14em;
  text-transform: uppercase; color: var(--blaze); margin-bottom: 8px;
}
.post-title {
  display: block;
  font-family: var(--display); font-weight: 700; font-size: clamp(22px, 3vw, 31px);
  line-height: 1.12; color: var(--pine); margin-bottom: 8px;
}
.post-dek { display: block; font-size: 16px; color: var(--pine-muted); max-width: 62ch; }
.post-more {
  display: inline-block; margin-top: 12px; font-size: 14px; font-weight: 600;
  color: var(--blaze); border-bottom: 2px solid transparent;
}
@media (max-width: 720px) {
  .post-link { grid-template-columns: 1fr; gap: 8px; }
  .post-when { padding-top: 0; }
}

/* -------------------------------------------------------------- article */
.article { padding: 56px 0 24px; }
.article-head { max-width: 760px; }
.article-head .eyebrow { color: var(--blaze); }
.article-head h1 {
  font-family: var(--display); font-weight: 700;
  font-size: clamp(32px, 5.4vw, 52px); line-height: 1.04;
  letter-spacing: -0.015em; color: var(--pine); margin: 16px 0 18px;
}
.article-dek { font-size: clamp(17px, 2vw, 20px); line-height: 1.6; color: var(--pine-soft); max-width: 52ch; }
.article-meta {
  display: flex; flex-wrap: wrap; gap: 8px 18px; margin-top: 24px;
  padding-top: 16px; border-top: var(--rule);
  font-size: 13.5px; font-weight: 600; color: var(--pine-muted);
}
.article-meta span { display: inline-flex; align-items: center; gap: 7px; }
.article-meta span::before { content: ''; width: 7px; height: 7px; background: var(--ochre); transform: rotate(45deg); }

.prose { max-width: var(--measure); margin-top: 40px; }
.prose > * + * { margin-top: 20px; }
.prose h2 {
  font-family: var(--display); font-weight: 700;
  font-size: clamp(24px, 3.4vw, 32px); line-height: 1.15;
  letter-spacing: -0.01em; color: var(--pine); margin-top: 46px;
}
.prose h3 {
  font-family: var(--display); font-weight: 700; font-size: 21px; line-height: 1.2;
  color: var(--pine); margin-top: 34px;
}
.prose p { font-size: 17.5px; }
.prose ul, .prose ol { margin-top: 18px; padding-left: 22px; }
.prose li { margin-bottom: 10px; font-size: 17.5px; }
.prose li::marker { color: var(--blaze); }
.prose strong { color: var(--pine); font-weight: 600; }
.prose a { color: var(--blaze); text-decoration-thickness: 1px; text-underline-offset: 2px; }
.prose a:hover { text-decoration-thickness: 2px; }
.prose blockquote {
  border-left: 4px solid var(--ochre); padding: 4px 0 4px 22px;
  font-family: var(--display); font-weight: 700; font-size: 21px; line-height: 1.35; color: var(--pine);
}

.callout {
  background: var(--cut); border: var(--rule); padding: 24px 26px 22px; margin-top: 32px;
}
.callout h3 {
  font-family: var(--display); font-weight: 700; font-size: 13px; letter-spacing: .14em;
  text-transform: uppercase; color: var(--pine); margin: 0 0 12px;
  border-bottom: var(--rule); padding-bottom: 10px;
}
.callout ul { margin: 0; padding-left: 20px; }
.callout li { font-size: 16px; margin-bottom: 8px; }
.callout p { font-size: 16px; margin-bottom: 8px; }
.callout > *:last-child { margin-bottom: 0; }

.table-wrap { margin-top: 30px; overflow-x: auto; border: var(--rule); background: var(--cut); }
table { border-collapse: collapse; width: 100%; min-width: 520px; }
caption {
  caption-side: top; text-align: left; font-size: 13px; font-weight: 600;
  letter-spacing: .1em; text-transform: uppercase; color: var(--pine-muted); padding: 14px 16px 0;
}
th, td { text-align: left; padding: 14px 16px; border-bottom: 1px solid var(--contour); vertical-align: top; }
th {
  font-family: var(--display); font-weight: 700; font-size: 14px; letter-spacing: .04em;
  color: var(--pine); text-transform: uppercase; background: var(--paper);
}
td { font-size: 15.5px; color: var(--pine-soft); }
tbody tr:last-child td { border-bottom: 0; }
td strong { color: var(--pine); }
/* Two-column tables fit a phone by wrapping; nothing here needs a scroll gutter. */
@media (max-width: 720px) {
  table { min-width: 0; }
  th, td { padding: 12px 14px; }
}

/* ------------------------------------------------------------------- CTA */
.post-cta {
  background-color: var(--pine);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='480' height='480' viewBox='0 0 480 480'%3E%3Cg fill='none' stroke='%23F2F4EF' stroke-width='1.4' opacity='0.07'%3E%3Cpath d='M-30 90 C 60 40, 150 140, 250 100 S 420 30, 510 80'/%3E%3Cpath d='M-30 160 C 60 110, 160 210, 260 170 S 430 100, 510 150'/%3E%3Cpath d='M-30 230 C 70 180, 170 280, 270 240 S 440 170, 510 220'/%3E%3Cpath d='M-30 300 C 60 250, 160 350, 260 310 S 430 240, 510 290'/%3E%3Cpath d='M-30 370 C 70 320, 170 420, 270 380 S 440 310, 510 360'/%3E%3Cpath d='M-30 440 C 60 390, 160 490, 260 450 S 430 380, 510 430'/%3E%3C/g%3E%3C/svg%3E");
  color: var(--paper);
  border-block: 3px solid var(--bark-deep);
  padding: 56px 0 60px;
  margin-top: 64px;
}
.post-cta .eyebrow { color: var(--ochre); }
.post-cta h2 {
  font-family: var(--display); font-weight: 700;
  font-size: clamp(26px, 3.8vw, 38px); line-height: 1.06; color: #fff; margin: 14px 0 14px;
}
.post-cta p { color: #C9D3CB; max-width: 52ch; margin-bottom: 26px; }
.post-cta .cta-note { font-size: 13.5px; color: #A9B7AC; margin: 18px 0 0; }
.post-cta .cta-actions { display: flex; flex-wrap: wrap; gap: 16px; align-items: center; }

.list-label {
  font-family: var(--display); font-weight: 700; font-size: 15px; letter-spacing: .14em;
  text-transform: uppercase; color: var(--pine); border-bottom: var(--rule);
  padding-bottom: 12px; margin-bottom: 0;
  display: flex; flex-wrap: wrap; align-items: baseline; gap: 6px 14px;
}
.list-label span { font-family: var(--body); font-weight: 600; font-size: 13px; letter-spacing: 0; text-transform: none; color: var(--pine-muted); }

.keep-reading { padding: 56px 0 0; }
.keep-reading h2 {
  font-family: var(--display); font-weight: 700; font-size: 15px; letter-spacing: .14em;
  text-transform: uppercase; color: var(--pine); border-bottom: var(--rule);
  padding-bottom: 12px; margin-bottom: 6px;
}
.keep-reading ul { list-style: none; }
.keep-reading li { border-bottom: 1px solid var(--contour); }
.keep-reading a {
  display: block; padding: 16px 0; text-decoration: none;
  font-family: var(--display); font-weight: 700; font-size: 19px; color: var(--pine);
}
.keep-reading a:hover { color: var(--blaze); }
.keep-reading a small {
  display: block; font-family: var(--body); font-weight: 400; font-size: 14px;
  color: var(--pine-muted); margin-top: 4px;
}

/* --------------------------------------------------------------- footer */
footer { background: var(--bark-deep); color: #C9D3CB; font-size: 14px; margin-top: 72px; }
.foot-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 32px; padding: 52px 0 40px; }
.foot-brand { display: flex; gap: 12px; align-items: flex-start; }
.foot-brand img { width: 34px; height: 34px; border-radius: 7px; }
.foot-brand .brand-name { font-size: 16px; color: var(--paper); }
.foot-brand p { font-size: 13px; color: #9FAFA3; margin-top: 8px; max-width: 30ch; line-height: 1.5; }
.foot-col h4 {
  font-family: var(--body); font-size: 11px; font-weight: 600; letter-spacing: .18em;
  text-transform: uppercase; color: var(--ochre); margin-bottom: 14px;
}
.foot-col a {
  display: block; text-decoration: none; color: #C9D3CB; padding: 4px 0;
  border-bottom: 1px solid transparent; width: fit-content;
}
.foot-col a:hover { color: #fff; border-bottom-color: var(--ochre); }
.foot-bottom {
  border-top: 1px solid #463A2E; padding: 18px 0 22px;
  display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px;
  font-size: 12.5px; color: #8D9C90;
}
@media (max-width: 800px) { .foot-grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 520px) { .foot-grid { grid-template-columns: 1fr; } }