/*
 * TyD Bureau — black on white, typography first.
 *
 * The governing rule: nothing decorative. No gradients, no shadows, no
 * motion, no rounded corners. If an element is not evidence or navigation,
 * it should not be here.
 */

:root {
  --ink: #000;
  --paper: #fff;
  --grey-1: #6b6b6b;   /* secondary text */
  --grey-2: #b8b8b8;   /* hairlines */
  --grey-3: #ededed;   /* block fills */

  --measure: 34rem;    /* readable line length for body copy */
  --page: 68rem;       /* outer page width */

  --sans: "IBM Plex Sans", system-ui, -apple-system, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, monospace;
  --serif: "IBM Plex Serif", Georgia, serif;
}

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

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1.0625rem;      /* 17px, set generously as agreed */
  line-height: 1.65;
  font-feature-settings: "kern" 1;
  text-rendering: optimizeLegibility;
}

/* ---------------------------------------------------------------- layout */

.page {
  max-width: var(--page);
  margin: 0 auto;
  padding: 0 1.5rem;
}

.prose { max-width: var(--measure); }

section { padding: 4.5rem 0; }
section + section { border-top: 1px solid var(--grey-2); }

/* ------------------------------------------------------------------- type */

h1, h2, h3 {
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin: 0 0 1rem;
  text-wrap: balance;
}

h1 { font-size: clamp(2.25rem, 6vw, 4rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); margin-bottom: 1.75rem; }
h3 { font-size: 1.125rem; }

p { margin: 0 0 1.25rem; }

a { color: var(--ink); text-underline-offset: 0.2em; }
a:hover { text-decoration-thickness: 2px; }

.lede {
  font-size: 1.25rem;
  line-height: 1.5;
  color: var(--grey-1);
}

.label {
  font-family: var(--mono);
  font-size: 0.75rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--grey-1);
}

/* ----------------------------------------------------------------- header */

.masthead {
  border-bottom: 1px solid var(--ink);
  /* Deliberately static: it does not shrink, blur, or float on scroll. */
}

.masthead__inner {
  display: flex;
  align-items: center;
  gap: 2rem;
  min-height: 4rem;
}

.wordmark {
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.03em;
  text-decoration: none;
}

.masthead nav {
  display: flex;
  gap: 1.5rem;
  margin-left: auto;
  flex-wrap: wrap;
}

.masthead nav a {
  text-decoration: none;
  font-size: 0.9375rem;
  color: var(--grey-1);
}

.masthead nav a:hover,
.masthead nav a[aria-current="page"] { color: var(--ink); }

/* ----------------------------------------------------------------- button */

.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border: 1px solid var(--ink);
  background: var(--ink);
  color: var(--paper);
  text-decoration: none;
  font-size: 0.9375rem;
  font-weight: 500;
}

.btn:hover { background: var(--paper); color: var(--ink); }

.btn--ghost { background: var(--paper); color: var(--ink); }
.btn--ghost:hover { background: var(--ink); color: var(--paper); }

.btn--small { padding: 0.4rem 0.9rem; font-size: 0.875rem; }

/* ------------------------------------------------------------------- hero */

.hero { padding: 6rem 0 4rem; }

.hero h1 { max-width: 20ch; margin-bottom: 1.5rem; }

.hero__actions {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin: 2.5rem 0 1rem;
}

.attribution {
  font-family: var(--mono);
  font-size: 0.8125rem;
  color: var(--grey-1);
  padding-top: 2rem;
  margin-top: 3rem;
  border-top: 1px solid var(--grey-2);
}

/* ----------------------------------------------------------------- figures */

.figures {
  display: flex;
  flex-wrap: wrap;
  gap: 3rem;
  margin: 0;
}

.figures div { margin: 0; }

.figures dd {
  font-family: var(--mono);
  font-size: clamp(2.5rem, 7vw, 4.5rem);
  line-height: 1;
  margin: 0 0 0.35rem;
  font-variant-numeric: tabular-nums;
}

.figures dt { order: 2; }

/* ------------------------------------------------------------------ lists */

.steps { counter-reset: step; list-style: none; padding: 0; margin: 0; }

.steps li {
  counter-increment: step;
  display: grid;
  grid-template-columns: 3rem 1fr;
  gap: 1.5rem;
  padding: 1.5rem 0;
  border-top: 1px solid var(--grey-2);
}

.steps li::before {
  content: counter(step, decimal-leading-zero);
  font-family: var(--mono);
  color: var(--grey-1);
  font-size: 0.875rem;
  padding-top: 0.3rem;
}

.steps h3 { margin-bottom: 0.25rem; }
.steps p { margin: 0; color: var(--grey-1); }

.grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
  gap: 2.5rem;
}

.topics { list-style: none; padding: 0; margin: 0; }

.topics li {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--grey-2);
}

.topics span:last-child {
  font-family: var(--mono);
  color: var(--grey-1);
  font-variant-numeric: tabular-nums;
}

/* ------------------------------------------------------------ instructor */

.instructor { display: grid; grid-template-columns: 20rem 1fr; gap: 3rem; }

.instructor img {
  width: 100%;
  height: auto;
  display: block;
  /* Print-like: no border, no radius, no shadow. Contrast lifted so the
     jacket reads near-black against the mid-grey backdrop. */
  filter: grayscale(100%) contrast(1.15);
}

@media (max-width: 46rem) {
  .instructor { grid-template-columns: 1fr; }
  .instructor img { max-width: 16rem; }
}

/* --------------------------------------------------------------- policies */

.policy { padding: 4rem 0 6rem; }
.policy h2 { font-size: 1.25rem; margin: 2.5rem 0 0.75rem; }
.policy ul { padding-left: 1.25rem; }
.policy li { margin-bottom: 0.5rem; }

.updated { font-family: var(--mono); font-size: 0.8125rem; color: var(--grey-1); }

/* Unfilled business details must be impossible to miss in review. */
.todo {
  background: var(--grey-3);
  border-left: 3px solid var(--ink);
  padding: 0.1rem 0.4rem;
  font-family: var(--mono);
  font-size: 0.875rem;
}

/* ----------------------------------------------------------------- footer */

.colophon {
  border-top: 1px solid var(--ink);
  padding: 3rem 0;
  font-size: 0.9375rem;
}

.colophon nav { display: flex; gap: 1.5rem; flex-wrap: wrap; margin-bottom: 1.5rem; }
.colophon address { font-style: normal; color: var(--grey-1); }

/* ------------------------------------------------------------------ print */

@media print {
  .masthead nav, .hero__actions { display: none; }
  body { font-size: 11pt; }
}