/* ============================================================
   USC Logic Web — shared course palette
   Mirrors the logic textbook (et-book, maroon, teal)
   ============================================================ */

@font-face {
  font-family: "et-book";
  src: url("https://gabriel-uzquiano.github.io/logic/libs/tufte-css-2015.12.29/et-book/roman-line-figures.ttf") format("truetype");
  font-weight: normal;
  font-style: normal;
}
@font-face {
  font-family: "et-book";
  src: url("https://gabriel-uzquiano.github.io/logic/libs/tufte-css-2015.12.29/et-book/bold-line-figures.ttf") format("truetype");
  font-weight: bold;
  font-style: normal;
}
@font-face {
  font-family: "et-book";
  src: url("https://gabriel-uzquiano.github.io/logic/libs/tufte-css-2015.12.29/et-book/display-italic-old-style-figures.ttf") format("truetype");
  font-weight: normal;
  font-style: italic;
}

:root {
  --font-body: et-book, Palatino, "Palatino Linotype", "Book Antiqua", Georgia, serif;
  --font-sans: "Gill Sans", "Gill Sans MT", Calibri, sans-serif;
  --color-bg:      #fffff8;
  --color-text:    #111111;
  --color-muted:   #666660;
  --color-border:  #ddd8ce;
  --color-primary: #7a1a3a;
  --color-teal:    #006666;
}

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

html { font-size: 21px; }

body {
  font-family: var(--font-body);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.65;
  padding: 3rem 2rem 5rem;
  max-width: 800px;
  margin: 0 auto;
}

/* ── Header ──────────────────────────────────────────────── */
.site-header {
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 1rem;
  margin-bottom: 0.5rem;
}
.site-header .course-label {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-muted);
}
.site-header h1 {
  font-size: 2rem;
  font-weight: normal;
  font-style: italic;
  color: var(--color-text);
  margin-top: 0.1rem;
  line-height: 1.2;
}

/* ── Breadcrumb ──────────────────────────────────────────── */
.breadcrumb {
  font-family: var(--font-sans);
  font-size: 0.78rem;
  color: var(--color-muted);
  margin: 0.8rem 0 1.8rem;
}
.breadcrumb a { color: var(--color-teal); text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }
.breadcrumb span { margin: 0 0.3em; }

/* ── Body text ───────────────────────────────────────────── */
p { margin-bottom: 1rem; }
em { font-style: italic; }
strong { font-weight: bold; }
a { color: var(--color-teal); }
a:hover { text-decoration: underline; }

/* ── Section headings ────────────────────────────────────── */
h2 {
  font-size: 1.3rem;
  font-weight: normal;
  font-style: italic;
  color: var(--color-text);
  border-top: 1px solid var(--color-border);
  margin: 2.5rem 0 0.6rem;
  padding-top: 0.3rem;
}

/* ── Unit list ───────────────────────────────────────────── */
.unit-list {
  list-style: none;
  margin: 1rem 0 0;
  padding: 0;
}
.unit-list li {
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--color-border);
}
.unit-list li:first-child { border-top: 1px solid var(--color-border); }
.unit-label {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  color: var(--color-muted);
  margin-right: 0.5em;
  letter-spacing: 0.03em;
}
.coming-soon {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  color: var(--color-muted);
  margin-left: 0.4em;
}

/* ── Instruction boxes ───────────────────────────────────── */
.instructions {
  border-left: 3px solid var(--color-teal);
  padding: 0.6rem 0.9rem;
  margin: 0.5rem 0 1.75rem;
  font-size: 0.91rem;
  line-height: 1.55;
  background: #f5fbfb;
}

/* ── Exercise blocks ─────────────────────────────────────── */
.exercise {
  margin: 0 0 2.5rem;
}
.exercise-label {
  font-family: var(--font-sans);
  font-size: 0.83rem;
  color: var(--color-muted);
  margin-bottom: 0.5rem;
}

/* ── Iframe wrapper ──────────────────────────────────────── */
.app-frame {
  position: relative;
  width: 100%;
}
.app-frame iframe {
  width: 100%;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  display: block;
  background: #fff;
}
/* Open link sits at top-right CORNER of the frame, outside the iframe */
.app-frame .open-btn {
  position: absolute;
  top: -1.4rem;
  right: 0;
  font-family: var(--font-sans);
  font-size: 0.72rem;
  color: var(--color-teal);
  text-decoration: none;
  white-space: nowrap;
}
.app-frame .open-btn:hover { text-decoration: underline; }