:root{
  --paper:#fbfaf6; --paper2:#f4f1e8; --card:#ffffff; --rule:#e3ddcd;
  --ink:#2b2823; --soft:#6f685b; --ochre:#a16207; --ochre2:#854d0e; --ochre-bg:#fdf6e9;
  --up:#3f7d4e; --down:#a24a3c;
  --serif:'Lora',Georgia,'Times New Roman',serif;
  --sans:'Karla',system-ui,-apple-system,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);
  line-height:1.7;font-size:17px;-webkit-font-smoothing:antialiased}
.tss-wrap{max-width:980px;margin:0 auto;padding:0 24px}
a{color:var(--ochre2);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3{font-family:var(--serif);line-height:1.22;font-weight:600;color:#221f1a}
h1{letter-spacing:-.01em}
h2{font-size:clamp(1.45rem,2.6vw,1.95rem);margin:0 0 .55em}
h3{font-size:1.16rem;margin:1.5em 0 .3em}
p{margin:.75em 0}
.tss-soft{color:var(--soft)}
section{padding:46px 0}
section + section{border-top:1px solid var(--rule)}
.tss-eyebrow{font-family:var(--sans);font-weight:700;font-size:.74rem;letter-spacing:.18em;
  text-transform:uppercase;color:var(--ochre);margin-bottom:13px}
/* lesson navigation bar */
.tss-bar{position:sticky;top:0;z-index:50;display:flex;align-items:center;justify-content:space-between;
  gap:18px;padding:14px 24px;background:rgba(251,250,246,.92);backdrop-filter:blur(8px);
  border-bottom:1px solid var(--rule)}
.tss-logo{display:flex;align-items:baseline;gap:8px;font-family:var(--serif);font-weight:600;
  font-size:1.06rem;color:#221f1a}
.tss-logo .dot{font-family:var(--sans);font-size:.66rem;letter-spacing:.16em;text-transform:uppercase;
  color:var(--ochre);font-weight:700}
.tss-links{display:flex;gap:22px;list-style:none;margin:0;padding:0;font-size:.94rem}
.tss-links a{color:var(--soft)}
.tss-links a:hover{color:var(--ink);text-decoration:none}
.tss-go{border:1px solid var(--ochre);color:var(--ochre2)!important;padding:8px 15px;border-radius:6px;
  font-weight:600;font-size:.88rem}
.tss-go:hover{background:var(--ochre-bg);text-decoration:none}
.tss-burger{display:none;background:none;border:0;cursor:pointer;width:30px;height:24px}
.tss-burger span{display:block;height:2px;background:var(--ink);margin:5px 0;border-radius:2px}
.tss-drawer{display:none;flex-direction:column;padding:6px 24px 18px;border-bottom:1px solid var(--rule);
  background:var(--paper2)}
.tss-drawer a{color:var(--ink);padding:11px 0;border-bottom:1px solid var(--rule);font-size:1rem}
.tss-drawer.open{display:flex}
/* opening / lead */
.tss-open{padding:64px 0 44px;background:linear-gradient(180deg,var(--paper2),var(--paper))}
.tss-kick{font-family:var(--sans);font-weight:700;font-size:.78rem;letter-spacing:.16em;
  text-transform:uppercase;color:var(--ochre)}
.tss-open h1{font-size:clamp(2.1rem,4.6vw,3.05rem);margin:.3em 0 .35em;max-width:18ch}
.tss-stand{font-size:1.18rem;color:#433f37;max-width:62ch}
.tss-facts{display:flex;flex-wrap:wrap;gap:11px;margin-top:26px;font-size:.9rem}
.tss-fact{background:var(--card);border:1px solid var(--rule);border-radius:999px;padding:8px 15px;color:var(--soft)}
.tss-fact b{color:var(--ochre2);font-weight:700}
.tss-act{display:inline-block;margin-top:28px;background:var(--ochre);color:#fff;font-weight:700;
  padding:13px 24px;border-radius:7px;font-size:.98rem}
.tss-act:hover{background:var(--ochre2);text-decoration:none}
.tss-read{font-size:1.1rem;color:#3b3730;max-width:66ch}
/* panels & cards */
.tss-note{background:var(--card);border:1px solid var(--rule);border-radius:14px;padding:26px 28px;margin:22px 0}
.tss-note.lit{border-color:#e7c98a;background:var(--ochre-bg)}
.tss-deck{display:grid;gap:18px}
@media(min-width:720px){.tss-three{grid-template-columns:repeat(3,1fr)}.tss-two{grid-template-columns:1fr 1fr}}
.tss-tile{background:var(--card);border:1px solid var(--rule);border-radius:13px;padding:22px}
.tss-tile h3{margin-top:0}
.tss-step{font-family:var(--serif);font-size:1.6rem;color:var(--ochre);font-weight:600;line-height:1}
.tss-mark{font-family:var(--sans);font-size:.72rem;font-weight:700;letter-spacing:.12em;
  text-transform:uppercase;color:var(--ochre)}
/* list of points */
.tss-points{list-style:none;padding:0;margin:18px 0}
.tss-points li{position:relative;padding:11px 0 11px 30px;border-bottom:1px solid var(--rule);color:#3b3730}
.tss-points li:before{content:"";position:absolute;left:4px;top:18px;width:9px;height:9px;
  border:2px solid var(--ochre);border-radius:2px;transform:rotate(45deg)}
/* record table */
.tss-scroll{overflow-x:auto;margin:22px 0}
table{border-collapse:collapse;width:100%;font-size:.94rem;min-width:520px}
caption{caption-side:bottom;text-align:left;color:var(--soft);font-size:.84rem;padding-top:10px}
th,td{padding:12px 14px;border-bottom:1px solid var(--rule);text-align:left}
thead th{font-family:var(--sans);font-size:.72rem;letter-spacing:.08em;text-transform:uppercase;
  color:var(--soft);font-weight:700}
tbody tr.flag td{background:var(--ochre-bg)}
td .gain{color:var(--up);font-weight:700}
/* breadcrumb + prose */
.tss-trail{font-size:.84rem;color:var(--soft);padding:18px 0 0}
.tss-trail a{color:var(--soft)}
.tss-trail .div{opacity:.5;margin:0 6px}
.tss-lede{font-size:1.18rem;color:#433f37;max-width:64ch;margin:.5em 0 0}
.tss-prose h2,.tss-prose h3{color:var(--ochre2)}
.tss-prose h2{font-size:1.34rem;margin:1.5em 0 .3em}
.tss-prose code{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;font-size:.86em;
  background:var(--paper2);padding:2px 6px;border-radius:4px;color:var(--ochre2)}
.tss-aside{border-left:3px solid var(--ochre);background:var(--ochre-bg);padding:6px 0 6px 16px;
  margin:20px 0;color:#4a4439;font-size:.96rem}
/* footer */
.tss-foot{border-top:1px solid var(--rule);background:var(--paper2);margin-top:34px;padding:44px 0 32px}
.tss-foot .grid{display:grid;gap:24px}
@media(min-width:720px){.tss-foot .grid{grid-template-columns:2fr 1fr 1fr 1fr}}
.tss-foot a{color:var(--soft);display:block;padding:3px 0}
.tss-foot a:hover{color:var(--ochre2)}
.tss-foot .head{color:#221f1a;font-family:var(--serif);font-size:.98rem;font-weight:600;margin-bottom:10px}
.tss-fine{color:#8a8273;font-size:.83rem;margin-top:26px;border-top:1px solid var(--rule);padding-top:18px}
/* worked-example callout: a ruled paper card distinct from .tss-note (own classes) */
.tss-worked{background:var(--paper2);border:1px solid var(--rule);border-left:3px solid var(--ochre);
  border-radius:0 12px 12px 0;padding:20px 24px;margin:24px 0}
.tss-worked .tss-mark{margin-bottom:12px}
.tss-worked ol{margin:0;padding-left:22px}
.tss-worked ol li{padding:7px 0;color:#3b3730}
.tss-worked ol li b{color:#221f1a}
.tss-worked .calc{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;font-size:.9rem;
  background:var(--card);border:1px solid var(--rule);border-radius:8px;padding:14px 16px;margin:14px 0;
  color:#433f37;line-height:1.9}
.tss-worked .calc b{color:var(--ochre2)}
/* on-brand inline diagram frame (distinct .tssd-* namespace; not BDS's .diagram/.d-*) */
figure.tss-fig{margin:26px 0;background:var(--card);border:1px solid var(--rule);border-radius:14px;
  padding:20px 20px 12px}
figure.tss-fig svg{display:block;width:100%;height:auto;max-width:780px;margin:0 auto}
figure.tss-fig figcaption{font-size:.86rem;color:var(--soft);text-align:center;margin-top:12px;
  max-width:60ch;margin-left:auto;margin-right:auto}
.tssd-card{fill:#ffffff;stroke:#e3ddcd;stroke-width:1.2}
.tssd-band{fill:#fdf6e9;stroke:#e7c98a;stroke-width:1}
.tssd-line{stroke:#a16207;stroke-width:2;fill:none}
.tssd-line.thin{stroke-width:1.4;stroke-dasharray:4 4;opacity:.85}
.tssd-h{font-family:'Lora',Georgia,serif;font-size:12px;fill:#221f1a;font-weight:600}
.tssd-t{font-family:'Karla',system-ui,sans-serif;font-size:10px;fill:#6f685b}
.tssd-tag{font-family:'Karla',system-ui,sans-serif;font-size:10.5px;font-weight:700;fill:#854d0e}
.tssd-good{font-family:'Karla',system-ui,sans-serif;font-size:11px;font-weight:700;fill:#3f7d4e}
.tssd-bad{font-family:'Karla',system-ui,sans-serif;font-size:11px;font-weight:700;fill:#a24a3c}
.tssd-ax{font-family:'Karla',system-ui,sans-serif;font-size:10px;fill:#8a8273}
.tssd-dot{fill:#854d0e}
/* 'Related' block at the foot of a leaf / hub page */
.tss-related{margin:34px 0 0;border-top:1px solid var(--rule);padding-top:22px}
.tss-related .head{font-family:var(--sans);font-size:.74rem;letter-spacing:.16em;text-transform:uppercase;
  color:var(--ochre);margin-bottom:14px;font-weight:700}
.tss-related .grid{display:grid;gap:11px}
@media(min-width:620px){.tss-related .grid{grid-template-columns:1fr 1fr}}
.tss-related a.rl{display:block;border:1px solid var(--rule);border-radius:11px;padding:13px 16px;
  background:var(--card);color:var(--ink)}
.tss-related a.rl:hover{border-color:#e7c98a;text-decoration:none}
.tss-related a.rl b{color:var(--ochre2);display:block;font-size:.96rem;font-family:var(--serif);font-weight:600}
.tss-related a.rl span{color:var(--soft);font-size:.85rem}
@media(max-width:719px){.tss-links{display:none}.tss-burger{display:block}}

/* a11y + responsive polish */
:focus-visible{outline:2px solid currentColor;outline-offset:3px;border-radius:3px}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{animation-duration:.01ms !important;transition-duration:.01ms !important}}
@media(max-width:719px){table{min-width:0}th,td{padding:8px 10px}}
/* mobile: record tables reflow to label:value cards instead of side-scrolling */
@media(max-width:768px){.tss-scroll{overflow-x:visible}.tss-scroll table{min-width:0}.tss-scroll thead{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}.tss-scroll tbody tr{display:block;border:1px solid var(--rule);border-radius:8px;background:var(--card);margin:0 0 14px;padding:6px 14px}.tss-scroll tbody tr.flag{border-color:var(--ochre);background:var(--ochre-bg)}.tss-scroll tbody td{display:flex;justify-content:space-between;gap:16px;align-items:baseline;border-bottom:1px solid var(--rule);padding:9px 0;text-align:right}.tss-scroll tbody tr td:last-child{border-bottom:0}.tss-scroll tbody td::before{content:attr(data-label);font-family:var(--sans);font-size:.72rem;letter-spacing:.06em;text-transform:uppercase;color:var(--soft);text-align:left;flex:0 0 auto;font-weight:600}.tss-scroll tbody td:first-child{flex-direction:column;align-items:flex-start;text-align:left;gap:2px}}