/* Course site styles, ported from the homepage (jhoffman.github.io css/style.css).
   Token names match the homepage so the two can be kept in sync. */

:root {
  /* Base & Surfaces */
  --color-bg:            #ffffff;  /* pure white background */
  --color-surface:       #f7f9fa;  /* very light gray cards/sections */
  --color-surface-hover: #eceff1;  /* slightly darker surface for hover states */

  /* Text & Primary */
  --color-primary:    #2e3a59;  /* dark slate – for headings/nav bg */
  --color-text:       #343a40;  /* charcoal – for body text */

  --color-header-title: #f1f1f1;
  --color-nav-link:     #CFD8DC;

  /* Accent. --color-accent is for borders, rules and fills only: it is 3.3:1
     on white, below the 4.5:1 AA minimum for text. Text links use --color-link,
     which passes on every surface below (5.9:1 on white, 5.1:1 on surface-hover). */
  --color-accent:       #4a90e2;
  --color-accent-light: #d0e6fc;
  --color-link:         #1a64b0;

  /* Muted: darker than the homepage's #6c757d, which is 4.4:1 on --color-surface */
  --color-muted-text: #5f6b73;

  /* Status tags (text on these fills is --color-primary, >= 8:1) */
  --color-due:    #fff3bf;
  --color-out:    #e0f2fd;
  --color-cancel: #fde2e4;
  --color-exam:   #e6f4ea;

  /* Typography */
  --font-sans: "Source Sans 3", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-heading: var(--font-sans);

  /* Spacing */
  --spacing-mini: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 2rem;

  /* Border radius */
  --radius: 0.5rem;
}

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

/* 106.25% ~= 17px root, as on the homepage. A percentage keeps the
   browser's own font-size setting honoured. */
html {
  font-size: 106.25%;
  /* keep anchor targets (#late-policy etc.) clear of the sticky header */
  scroll-padding-top: 5rem;
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
}

main {
  max-width: 960px;
  margin: var(--spacing-lg) auto;
  padding: 0 var(--spacing-md);
}

/* main is a skip-link target; it takes focus but needs no ring of its own */
main:focus {
  outline: none;
}

h1, h2, h3, h4 {
  font-family: var(--font-heading);
  color: var(--color-primary);
  margin-top: 0;
  line-height: 1.25;
  font-weight: 600;
}

h1 {
  font-size: clamp(1.5rem, 1.24rem + 1.16vw, 1.9rem);
  margin-bottom: var(--spacing-md);
}

h2 {
  font-size: clamp(1.25rem, 1.03rem + 1.02vw, 1.6rem);
}

h3 {
  font-size: clamp(1.1rem, 1.04rem + 0.29vw, 1.2rem);
}

h4 {
  font-size: 1rem;
}

* + h2,
* + h3,
* + h4 {
  margin-top: var(--spacing-lg);
}

.page-subtitle {
  margin: calc(-1 * var(--spacing-sm)) 0 var(--spacing-lg);
  color: var(--color-muted-text);
  font-size: 1.1rem;
}

/* Images */
img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Links. Underlined inside page content so they are not told apart from
   body text by colour alone (WCAG 1.4.1). */
a {
  color: var(--color-link);
  text-decoration: none;
}

main a,
footer a {
  text-decoration: underline;
  text-underline-offset: 0.15em;
}

a:hover {
  text-decoration: underline;
  text-decoration-thickness: 2px;
}

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--color-link);
  outline-offset: 2px;
}

/* Skip link: off-screen until focused */
.skip-link {
  position: absolute;
  left: var(--spacing-md);
  top: -3rem;
  z-index: 2000;
  padding: var(--spacing-sm) var(--spacing-md);
  background: var(--color-bg);
  color: var(--color-link);
  font-weight: 600;
  border-radius: var(--radius);
  box-shadow: 0 2px 6px rgba(0,0,0,0.2);
}

.skip-link:focus {
  top: var(--spacing-sm);
}

/* Cards: same treatment as the homepage's news/publication cards */
.card {
  background-color: var(--color-surface);
  border-radius: var(--radius);
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
  padding: var(--spacing-md) var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
}

.card > :first-child {
  margin-top: 0;
}

.card > :last-child {
  margin-bottom: 0;
}

/* Key facts at the top of the home page */
.facts {
  display: grid;
  grid-template-columns: max-content 1fr;
  gap: var(--spacing-mini) var(--spacing-md);
  margin: 0;
}

.facts dt {
  font-weight: 600;
  color: var(--color-primary);
}

.facts dd {
  margin: 0;
}

.muted {
  color: var(--color-muted-text);
}

/* Course staff: works for one card or several; cards keep a fixed width and
   centre as a group, so two cards read as a balanced pair. */
.staff-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--spacing-lg);
  list-style: none;
  margin: var(--spacing-md) 0 0;
  padding: 0;
}

.staff-card {
  flex: 0 1 16rem;
  background-color: var(--color-bg);
  border-radius: var(--radius);
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
  padding: var(--spacing-md);
  text-align: center;
}

.staff-card img {
  width: 120px;
  height: 120px;
  object-fit: cover;
  border-radius: 50%;
  margin: 0 auto var(--spacing-sm);
}

.staff-card h3 {
  margin: 0 0 var(--spacing-mini);
}

.staff-card p {
  margin: 0 0 var(--spacing-mini);
}

.staff-role {
  color: var(--color-muted-text);
  font-weight: 600;
}

/* Status tags: always carry a text label, colour is secondary */
.tag {
  display: inline-block;
  padding: 0.05em 0.5em;
  border-radius: var(--radius);
  color: var(--color-primary);
  font-size: 0.85rem;
  font-weight: 600;
  white-space: nowrap;
}

.tag-due    { background-color: var(--color-due); }
.tag-cancel { background-color: var(--color-bg); }
.tag-exam   { background-color: var(--color-exam); }
.tag-lab    { background-color: var(--color-out); }
.tag-optional { background-color: var(--color-surface-hover); }

/* Callout: an accent rule, as on the homepage's research statement */
.note {
  margin: 0 0 var(--spacing-md);
  padding-left: var(--spacing-md);
  border-left: 3px solid var(--color-accent);
}

/* Footer */
footer {
  text-align: center;
  padding: var(--spacing-md);
  background-color: var(--color-surface);
  color: var(--color-muted-text);
  font-size: 0.875rem;
}

footer p {
  margin: 0;
}

@media (max-width: 600px) {
  .card {
    padding: var(--spacing-md);
  }

  .facts {
    grid-template-columns: 1fr;
  }

  .facts dd {
    margin-bottom: var(--spacing-sm);
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition: none !important;
    animation: none !important;
  }
}

/* Markdown tables inside cards (grading breakdowns) */
.card table:not(.data-table) {
  border-collapse: collapse;
  margin: var(--spacing-md) 0;
  background: var(--color-bg);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.card table:not(.data-table) th,
.card table:not(.data-table) td {
  padding: var(--spacing-sm) var(--spacing-md);
  text-align: left;
  border-bottom: 1px solid #e3e7ea;
}

.card table:not(.data-table) thead th {
  background: var(--color-primary);
  color: #ffffff;
  font-weight: 600;
}

/* On-page contents for long pages */
.toc p {
  margin: 0;
  line-height: 1.9;
}

@media (max-width: 600px) {
  .card table:not(.data-table) th,
  .card table:not(.data-table) td {
    padding: var(--spacing-sm);
  }

  .card table:not(.data-table) code {
    word-break: break-all;
  }
}