/* ============================================================
   Shared stylesheet for the "Electronics for Building Things" course.
   Tufte-inspired: readable measure, generous margins, sidenotes,
   restrained color, prints cleanly. Linked by every lesson and
   reference document.
   ============================================================ */

:root {
  --ink:        #1a1a1a;
  --paper:      #fdfdfa;
  --muted:      #6b6b6b;
  --rule:       #e2e0d8;
  --accent:     #b3461f;   /* warm copper — wires/current */
  --accent-2:   #1f6f8b;   /* teal — voltage/info */
  --good:       #2e7d32;
  --bad:        #c62828;
  --code-bg:    #f4f2ec;
  --highlight:  #fff6d6;
  --maxw:       42rem;
}

* { box-sizing: border-box; }

html { font-size: 18px; }

body {
  background: var(--paper);
  color: var(--ink);
  font-family: et-book, Palatino, "Palatino Linotype", "Book Antiqua", Georgia, serif;
  line-height: 1.55;
  margin: 0;
  padding: 0;
}

.wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 3rem 1.5rem 6rem;
}

/* ---- Course / lesson header ---- */
.eyebrow {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 0.4rem;
}
h1 {
  font-weight: 400;
  font-size: 2.1rem;
  line-height: 1.15;
  margin: 0 0 0.3rem;
}
.subtitle {
  font-style: italic;
  color: var(--muted);
  font-size: 1.1rem;
  margin: 0 0 1.5rem;
}

h2 {
  font-weight: 400;
  font-size: 1.4rem;
  margin: 2.6rem 0 0.6rem;
  padding-bottom: 0.2rem;
  border-bottom: 1px solid var(--rule);
}
h3 {
  font-weight: 600;
  font-size: 1.05rem;
  margin: 1.6rem 0 0.4rem;
}

p { margin: 0.8rem 0; }

a { color: var(--accent-2); text-decoration: none; border-bottom: 1px solid rgba(31,111,139,0.3); }
a:hover { border-bottom-color: var(--accent-2); }

strong { font-weight: 600; }
em { font-style: italic; }

/* ---- Key terms ---- */
.term {
  font-weight: 600;
  color: var(--accent);
  font-style: normal;
}

/* ---- Callouts ---- */
.callout {
  border-left: 3px solid var(--accent-2);
  background: #f3f7f8;
  padding: 0.8rem 1.1rem;
  margin: 1.4rem 0;
  border-radius: 0 4px 4px 0;
}
.callout.rule   { border-left-color: var(--accent); background: #faf2ee; }
.callout.danger { border-left-color: var(--bad);    background: #fcefef; }
.callout .label {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 0.68rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  font-weight: 700;
  display: block;
  margin-bottom: 0.3rem;
  color: var(--muted);
}
.callout.rule .label   { color: var(--accent); }
.callout.danger .label { color: var(--bad); }

/* ---- The water analogy box ---- */
.analogy {
  background: var(--code-bg);
  border-radius: 6px;
  padding: 1.2rem 1.4rem;
  margin: 1.4rem 0;
}

/* ---- Comparison table ---- */
table {
  border-collapse: collapse;
  width: 100%;
  margin: 1.4rem 0;
  font-size: 0.95rem;
}
th, td {
  text-align: left;
  padding: 0.55rem 0.7rem;
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
}
th {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

/* ---- Inline code & key facts ---- */
code {
  font-family: "SF Mono", "Fira Code", Menlo, Consolas, monospace;
  background: var(--code-bg);
  padding: 0.1rem 0.35rem;
  border-radius: 3px;
  font-size: 0.86em;
}
mark { background: var(--highlight); padding: 0 0.15rem; }

/* ---- Figures / SVG diagrams ---- */
figure { margin: 1.8rem 0; text-align: center; }
figure svg { max-width: 100%; height: auto; }
figcaption {
  font-size: 0.85rem;
  color: var(--muted);
  font-style: italic;
  margin-top: 0.6rem;
}

/* ---- Navigation footer between lessons ---- */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--rule);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 0.85rem;
}

/* ---- "Ask your teacher" reminder ---- */
.ask-teacher {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 0.9rem;
  background: #f3f7f8;
  border: 1px dashed var(--accent-2);
  border-radius: 6px;
  padding: 0.9rem 1.1rem;
  margin: 2rem 0;
}
.ask-teacher strong { color: var(--accent-2); }

/* ---- Primary source recommendation ---- */
.primary-source {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 0.92rem;
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 1rem 1.2rem;
  margin: 1.6rem 0;
}
.primary-source .label {
  font-size: 0.68rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
  display: block;
  margin-bottom: 0.3rem;
}

/* ---- Print ---- */
@media print {
  :root { --paper: #fff; }
  body { font-size: 12pt; }
  .ask-teacher, .lesson-nav, .quiz button { display: none; }
  a { color: var(--ink); border: none; }
  .wrap { max-width: 100%; }
}