/* ==========================================================================
   lesson.css — shared design system for the Game Feel teaching workspace.
   Tufte-inspired: generous margins, serif body, sidenotes, restrained colour.
   Every lesson and reference document links this file.
   ========================================================================== */

:root {
  --bg:        #fffff8;
  --ink:       #14110d;
  --ink-soft:  #4a4540;
  --ink-faint: #8b857d;
  --rule:      #ddd8cc;
  --accent:    #a8322d;   /* used sparingly: links, emphasis, the "designed" curve */
  --accent-2:  #2f6f8f;   /* secondary: the "textbook physics" curve */
  --good:      #2d6a3f;
  --bad:       #a8322d;
  --panel:     #f6f4ea;
  --code-bg:   #f3f1e7;

  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua",
           Georgia, "Times New Roman", serif;
  --sans:  "Inter", "Helvetica Neue", -apple-system, BlinkMacSystemFont, sans-serif;
  --mono:  "SF Mono", "JetBrains Mono", Menlo, Consolas, "Liberation Mono", monospace;
}

/* --- reset & base ------------------------------------------------------- */

* { box-sizing: border-box; }

html { font-size: 17px; }

body {
  margin: 0 auto;
  padding: 4rem 2rem 8rem;
  max-width: 46rem;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--serif);
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* --- masthead ----------------------------------------------------------- */

.masthead {
  border-bottom: 1px solid var(--rule);
  padding-bottom: 1.2rem;
  margin-bottom: 2.5rem;
}

.eyebrow {
  font-family: var(--sans);
  font-size: 0.72rem;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 0 0 0.6rem;
}

.eyebrow a { color: inherit; }

h1 {
  font-weight: 400;
  font-size: 2.5rem;
  line-height: 1.12;
  letter-spacing: -0.015em;
  margin: 0 0 0.5rem;
}

.subtitle {
  font-style: italic;
  color: var(--ink-soft);
  font-size: 1.12rem;
  margin: 0;
}

/* --- headings ----------------------------------------------------------- */

h2 {
  font-weight: 400;
  font-size: 1.55rem;
  letter-spacing: -0.01em;
  margin: 3.2rem 0 0.8rem;
}

h3 {
  font-weight: 600;
  font-size: 1.06rem;
  font-family: var(--sans);
  letter-spacing: 0.01em;
  margin: 2rem 0 0.6rem;
}

h2 .num {
  font-family: var(--sans);
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  color: var(--ink-faint);
  vertical-align: 0.5em;
  margin-right: 0.55rem;
}

/* --- text --------------------------------------------------------------- */

p { margin: 0 0 1.1rem; }

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid rgba(168, 50, 45, 0.28);
}
a:hover { border-bottom-color: var(--accent); }

strong { font-weight: 650; }

em.key {
  font-style: normal;
  font-weight: 650;
  border-bottom: 2px solid rgba(168, 50, 45, 0.3);
}

blockquote {
  margin: 1.6rem 0;
  padding-left: 1.3rem;
  border-left: 2px solid var(--rule);
  color: var(--ink-soft);
  font-style: italic;
}
blockquote cite {
  display: block;
  margin-top: 0.5rem;
  font-style: normal;
  font-family: var(--sans);
  font-size: 0.8rem;
  color: var(--ink-faint);
}

ul, ol { margin: 0 0 1.1rem; padding-left: 1.3rem; }
li { margin-bottom: 0.42rem; }

/* --- sidenotes ---------------------------------------------------------- */

.sidenote {
  float: right;
  clear: right;
  width: 13rem;
  margin: 0.35rem -15rem 1rem 0;
  font-family: var(--sans);
  font-size: 0.76rem;
  line-height: 1.5;
  color: var(--ink-soft);
}
.sidenote a { font-size: inherit; }

@media (max-width: 1180px) {
  .sidenote {
    float: none;
    width: auto;
    margin: 1rem 0;
    padding: 0.7rem 0.9rem;
    background: var(--panel);
    border-left: 2px solid var(--rule);
  }
}

/* --- panels ------------------------------------------------------------- */

.panel {
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: 3px;
  padding: 1.2rem 1.4rem;
  margin: 1.8rem 0;
}
.panel > :last-child { margin-bottom: 0; }

.panel-label {
  font-family: var(--sans);
  font-size: 0.68rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 0 0 0.7rem;
}

.callout {
  border-left: 3px solid var(--accent);
  background: rgba(168, 50, 45, 0.045);
  padding: 1rem 1.2rem;
  margin: 1.8rem 0;
}
.callout > :last-child { margin-bottom: 0; }

/* --- math --------------------------------------------------------------- */

.formula {
  font-family: var(--serif);
  font-size: 1.16rem;
  text-align: center;
  margin: 1.5rem 0;
  line-height: 2.1;
}
.formula .var { font-style: italic; }
.formula .frac {
  display: inline-block;
  vertical-align: middle;
  text-align: center;
  margin: 0 0.25em;
}
.formula .frac .top { display: block; padding: 0 0.4em; }
.formula .frac .bot {
  display: block;
  padding: 0 0.4em;
  border-top: 1px solid var(--ink);
}
var {
  font-style: italic;
  font-family: var(--serif);
}

kbd {
  font-family: var(--sans);
  font-size: 0.78em;
  padding: 0.12em 0.42em;
  border: 1px solid var(--ink-faint);
  border-bottom-width: 2px;
  border-radius: 3px;
  background: #fff;
  white-space: nowrap;
}

.formula .label {
  font-family: var(--sans);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin-right: 1.2rem;
}

/* --- code --------------------------------------------------------------- */

pre {
  background: var(--code-bg);
  border: 1px solid var(--rule);
  border-radius: 3px;
  padding: 1rem 1.1rem;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 0.78rem;
  line-height: 1.62;
  margin: 1.4rem 0;
}
code {
  font-family: var(--mono);
  font-size: 0.84em;
  background: var(--code-bg);
  padding: 0.08em 0.32em;
  border-radius: 2px;
}
pre code { background: none; padding: 0; font-size: inherit; }

.tok-kw   { color: #9b2d8f; }
.tok-fn   { color: #2f6f8f; }
.tok-num  { color: #a8322d; }
.tok-str  { color: #2d6a3f; }
.tok-com  { color: var(--ink-faint); font-style: italic; }

/* --- tables ------------------------------------------------------------- */

table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--sans);
  font-size: 0.84rem;
  margin: 1.5rem 0;
}
th {
  text-align: left;
  font-weight: 600;
  font-size: 0.7rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-faint);
  border-bottom: 1px solid var(--ink);
  padding: 0.4rem 0.7rem 0.4rem 0;
}
td {
  padding: 0.5rem 0.7rem 0.5rem 0;
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
}

/* --- labs (interactive widgets) ----------------------------------------- */

.lab {
  border: 1px solid var(--rule);
  border-radius: 4px;
  background: #fff;
  margin: 2rem 0;
  overflow: hidden;
}

.lab-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.7rem 1rem;
  background: var(--panel);
  border-bottom: 1px solid var(--rule);
}
.lab-title {
  font-family: var(--sans);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--ink-soft);
}
.lab-hint {
  font-family: var(--sans);
  font-size: 0.74rem;
  color: var(--ink-faint);
}

.lab-canvas-wrap { padding: 0.8rem 1rem 0; }
.lab canvas {
  display: block;
  width: 100%;
  height: auto;
  background: #fbfaf4;
  border: 1px solid var(--rule);
  border-radius: 3px;
  touch-action: none;
}

.lab-controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: 0.55rem 1.6rem;
  padding: 1rem;
}

.ctrl { display: grid; grid-template-columns: 1fr auto; gap: 0.15rem 0.6rem; }
.ctrl label {
  font-family: var(--sans);
  font-size: 0.76rem;
  color: var(--ink-soft);
}
.ctrl output {
  font-family: var(--mono);
  font-size: 0.74rem;
  color: var(--ink);
  text-align: right;
  min-width: 4.5rem;
}
.ctrl input[type="range"] {
  grid-column: 1 / -1;
  width: 100%;
  margin: 0;
  accent-color: var(--accent);
}

.lab-readout {
  display: flex;
  flex-wrap: wrap;
  gap: 0 1.8rem;
  padding: 0 1rem 1rem;
  font-family: var(--mono);
  font-size: 0.74rem;
  color: var(--ink-soft);
}
.lab-readout b { color: var(--ink); font-weight: 600; }

.lab-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  padding: 0 1rem 1rem;
}

button {
  font-family: var(--sans);
  font-size: 0.78rem;
  padding: 0.4rem 0.9rem;
  border: 1px solid var(--ink-faint);
  border-radius: 3px;
  background: #fff;
  color: var(--ink);
  cursor: pointer;
}
button:hover { background: var(--panel); }
button:active { transform: translateY(1px); }
button.primary { background: var(--ink); color: var(--bg); border-color: var(--ink); }
button.primary:hover { background: #000; }

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0 1.4rem;
  padding: 0.5rem 1rem 0;
  font-family: var(--sans);
  font-size: 0.72rem;
  color: var(--ink-soft);
}
.legend span::before {
  content: "";
  display: inline-block;
  width: 1.5rem;
  height: 0;
  vertical-align: 0.22em;
  margin-right: 0.4rem;
  border-top-width: 2px;
  border-top-style: solid;
}
.legend .l-you::before    { border-color: var(--accent); }
.legend .l-text::before   { border-color: var(--accent-2); border-top-style: dashed; }
.legend .l-target::before { border-color: var(--ink-faint); border-top-style: dashed; }

/* --- quiz --------------------------------------------------------------- */

.quiz { margin: 2rem 0; }

.quiz-item {
  border: 1px solid var(--rule);
  border-radius: 4px;
  padding: 1rem 1.2rem;
  margin-bottom: 0.9rem;
  background: #fff;
}

.quiz-q {
  font-family: var(--serif);
  font-size: 1rem;
  margin: 0 0 0.85rem;
}
.quiz-q .qnum {
  font-family: var(--sans);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  color: var(--ink-faint);
  margin-right: 0.6rem;
}

.quiz-opts { display: grid; gap: 0.4rem; }

.quiz-opt {
  font-family: var(--sans);
  font-size: 0.83rem;
  text-align: left;
  padding: 0.5rem 0.8rem;
  border: 1px solid var(--rule);
  border-radius: 3px;
  background: #fff;
  cursor: pointer;
  transition: background 0.12s, border-color 0.12s;
}
.quiz-opt:hover:not(:disabled) { background: var(--panel); }
.quiz-opt:disabled { cursor: default; opacity: 0.55; }
.quiz-opt.correct {
  border-color: var(--good);
  background: rgba(45, 106, 63, 0.09);
  opacity: 1;
  color: var(--good);
  font-weight: 600;
}
.quiz-opt.wrong {
  border-color: var(--bad);
  background: rgba(168, 50, 45, 0.09);
  opacity: 1;
  color: var(--bad);
  font-weight: 600;
}

.quiz-why {
  display: none;
  margin-top: 0.8rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--rule);
  font-size: 0.9rem;
  color: var(--ink-soft);
}
.quiz-why.show { display: block; }

.quiz-score {
  font-family: var(--sans);
  font-size: 0.8rem;
  color: var(--ink-faint);
  padding-top: 0.4rem;
}

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

.footer {
  margin-top: 4rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--ink-soft);
}
.footer h3 { margin-top: 1.6rem; }
.footer p:first-of-type { margin-top: 0; }

.ask {
  background: var(--panel);
  border: 1px dashed var(--ink-faint);
  border-radius: 4px;
  padding: 0.9rem 1.1rem;
  margin: 2rem 0 0;
  font-family: var(--sans);
  font-size: 0.83rem;
  color: var(--ink-soft);
}
.ask strong { color: var(--ink); }

.nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 2rem;
  font-family: var(--sans);
  font-size: 0.8rem;
}

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

@media print {
  :root { --bg: #fff; }
  html { font-size: 11pt; }
  body { max-width: none; padding: 0; }
  .sidenote {
    float: none; width: auto; margin: 0.8rem 0;
    background: #f4f4f4; padding: 0.5rem 0.8rem;
  }
  .lab-controls, .lab-actions, .quiz-opts, .ask { display: none; }
  .quiz-why { display: block; }
  .lab { break-inside: avoid; }
  a { color: var(--ink); border: none; }
  a[href^="http"]::after {
    content: " (" attr(href) ")";
    font-size: 0.7em;
    color: #666;
    word-break: break-all;
  }
  h2 { break-after: avoid; }
  pre { break-inside: avoid; white-space: pre-wrap; }
}