/* =========================================================
   Agricultural Instrumentation & IoT — course site styles
   ========================================================= */

@import url("https://fonts.googleapis.com/css2?family=Sarabun:ital,wght@0,400;0,500;0,600;0,700;1,400&family=JetBrains+Mono:wght@400;600&display=swap");

:root {
  --bg: #f7f6f2;
  --surface: #ffffff;
  --surface-2: #f0efe9;
  --text: #1f2421;
  --text-muted: #5c645f;
  --border: #dcdbd3;
  --accent: #2f7d4f;          /* leaf green */
  --accent-soft: #e3f1e8;
  --accent-text: #1f5c38;
  --info: #2c6a9e;
  --info-soft: #e4eef7;
  --warn: #a8641a;
  --warn-soft: #fbefdf;
  --ok: #2f7d4f;
  --bad: #b3372f;
  --bad-soft: #f8e3e1;
  --sidebar-bg: #1e2b24;
  --sidebar-text: #d7e2da;
  --sidebar-muted: #8fa497;
  --sidebar-active: #7fd19e;
  --code-bg: #f0efe9;
  --shadow: 0 1px 2px rgba(0,0,0,.05), 0 4px 16px rgba(0,0,0,.04);

  --sidebar-w: 290px;
  --content-w: 860px;
  --radius: 10px;
  --font: "Sarabun", "Leelawadee UI", "Tahoma", system-ui, sans-serif;
  --mono: "JetBrains Mono", "Consolas", "Courier New", monospace;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #151a17;
    --surface: #1d2420;
    --surface-2: #242c27;
    --text: #e4e9e5;
    --text-muted: #9aa69f;
    --border: #334039;
    --accent: #6cc48e;
    --accent-soft: #1f3528;
    --accent-text: #9fdcb5;
    --info: #7fb4e0;
    --info-soft: #1d2c39;
    --warn: #e0a55e;
    --warn-soft: #362a1b;
    --ok: #6cc48e;
    --bad: #ec8a82;
    --bad-soft: #3a2220;
    --sidebar-bg: #111613;
    --code-bg: #242c27;
    --shadow: none;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #151a17; --surface: #1d2420; --surface-2: #242c27; --text: #e4e9e5;
  --text-muted: #9aa69f; --border: #334039; --accent: #6cc48e; --accent-soft: #1f3528;
  --accent-text: #9fdcb5; --info: #7fb4e0; --info-soft: #1d2c39; --warn: #e0a55e;
  --warn-soft: #362a1b; --ok: #6cc48e; --bad: #ec8a82; --bad-soft: #3a2220;
  --sidebar-bg: #111613; --code-bg: #242c27; --shadow: none;
  color-scheme: dark;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 72px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

img, svg { max-width: 100%; }

a { color: var(--info); text-underline-offset: 2px; }
a:hover { color: var(--accent); }

/* ---------------- Sidebar ---------------- */
.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  width: var(--sidebar-w);
  background: var(--sidebar-bg);
  color: var(--sidebar-text);
  overflow-y: auto;
  padding: 22px 0 32px;
  z-index: 40;
  font-size: 15px;
  line-height: 1.5;
  transition: transform .25s ease;
}
.sidebar .brand {
  display: block;
  padding: 0 22px 18px;
  margin-bottom: 10px;
  border-bottom: 1px solid rgba(255,255,255,.08);
  color: #fff;
  text-decoration: none;
}
.sidebar .brand .code { font-family: var(--mono); font-size: 12px; color: var(--sidebar-active); letter-spacing: .04em; }
.sidebar .brand .name { display: block; font-weight: 700; font-size: 17px; margin-top: 4px; }
.sidebar .brand .sub { display: block; font-size: 13px; color: var(--sidebar-muted); margin-top: 2px; }

.sidebar ul { list-style: none; margin: 0; padding: 0; }
.sidebar .chapter > a {
  display: flex;
  gap: 10px;
  align-items: baseline;
  padding: 9px 22px;
  color: var(--sidebar-text);
  text-decoration: none;
  border-left: 3px solid transparent;
}
.sidebar .chapter > a:hover { background: rgba(255,255,255,.05); color: #fff; }
.sidebar .chapter > a .num {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--sidebar-muted);
  min-width: 2.2em;
}
.sidebar .chapter.current > a {
  border-left-color: var(--sidebar-active);
  background: rgba(127,209,158,.08);
  color: #fff;
  font-weight: 600;
}
.sidebar .chapter.current > a .num { color: var(--sidebar-active); }

.sidebar .sections { padding: 4px 0 10px; }
.sidebar .sections a {
  display: block;
  padding: 5px 22px 5px 56px;
  color: var(--sidebar-muted);
  text-decoration: none;
  font-size: 14px;
  border-left: 3px solid transparent;
}
.sidebar .sections a:hover { color: #fff; }
.sidebar .sections a.active { color: var(--sidebar-active); border-left-color: rgba(127,209,158,.5); }

.sidebar .side-foot {
  margin: 24px 22px 0;
  padding-top: 16px;
  border-top: 1px solid rgba(255,255,255,.08);
  font-size: 12px;
  color: var(--sidebar-muted);
}

.sidebar-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.45);
  z-index: 35;
}

/* ---------------- Page frame ---------------- */
.page {
  margin-left: var(--sidebar-w);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 24px;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  font-size: 14px;
  color: var(--text-muted);
}
.topbar .crumb { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.menu-btn {
  display: none;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  border-radius: 8px;
  padding: 4px 10px;
  font: inherit;
  font-size: 18px;
  line-height: 1.2;
  cursor: pointer;
}

.content {
  width: 100%;
  max-width: calc(var(--content-w) + 48px);
  padding: 32px 24px 56px;
  margin: 0 auto;
  flex: 1;
}

/* ---------------- Footer ---------------- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 20px 24px 28px;
  text-align: center;
  font-size: 14px;
  color: var(--text-muted);
  background: var(--surface-2);
}

/* ---------------- Typography ---------------- */
h1, h2, h3, h4 { line-height: 1.35; font-weight: 700; }
h1 { font-size: 2.1rem; margin: 0 0 .4em; }
h2 {
  font-size: 1.5rem;
  margin: 2.6em 0 .7em;
  padding-top: .6em;
  border-top: 1px solid var(--border);
}
h2 .sec-no { color: var(--accent); font-family: var(--mono); font-size: .8em; margin-right: .4em; }
h3 { font-size: 1.18rem; margin: 1.8em 0 .5em; }
p { margin: .7em 0; }
ul, ol { padding-left: 1.4em; }
li { margin: .25em 0; }
strong { font-weight: 700; }
code, kbd {
  font-family: var(--mono);
  font-size: .86em;
  background: var(--code-bg);
  padding: .1em .35em;
  border-radius: 4px;
}
pre {
  font-family: var(--mono);
  font-size: 14px;
  line-height: 1.6;
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  overflow-x: auto;
}
pre code { background: none; padding: 0; font-size: inherit; }
.muted { color: var(--text-muted); }
.en { color: var(--text-muted); font-size: .92em; }

/* ---------------- Chapter header ---------------- */
.chapter-head {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 28px 28px 22px;
  box-shadow: var(--shadow);
}
.chapter-head .eyebrow {
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: .06em;
  color: var(--accent);
  text-transform: uppercase;
}
.chapter-head .lead { font-size: 1.08rem; color: var(--text-muted); margin: .2em 0 1em; }
.chapter-head .source { font-size: 13px; color: var(--text-muted); }

.objectives {
  margin-top: 18px;
  background: var(--accent-soft);
  border-radius: var(--radius);
  padding: 14px 18px;
}
.objectives h4 { margin: 0 0 .3em; font-size: 1rem; color: var(--accent-text); }
.objectives ul { margin: 0; }

/* ---------------- Callouts ---------------- */
.callout {
  border-left: 4px solid var(--info);
  background: var(--info-soft);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 12px 18px;
  margin: 1.2em 0;
}
.callout > :first-child { margin-top: 0; }
.callout > :last-child { margin-bottom: 0; }
.callout .title { font-weight: 700; display: block; margin-bottom: .2em; }
.callout.key { border-color: var(--accent); background: var(--accent-soft); }
.callout.warn { border-color: var(--warn); background: var(--warn-soft); }

/* ---------------- Equations ---------------- */
.eq {
  display: block;
  text-align: center;
  line-height: 2.2;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 18px;
  margin: 1em 0;
  font-size: 1.12rem;
  font-family: "Cambria Math", "Times New Roman", var(--font);
  overflow-x: auto;
}
.eq .label { float: right; margin-left: 1em; font-family: var(--font); font-size: .82rem; color: var(--text-muted); }
.frac {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  vertical-align: middle;
  line-height: 1.3;
  margin: 0 .15em;
}
.frac > span:first-child { border-bottom: 1.5px solid currentColor; padding: 0 .3em; }
.frac > span:last-child { padding: 0 .3em; }
var { font-style: italic; }

/* ตัวห้อย/ตัวยก: ไม่ดันระยะบรรทัด และขนาดสม่ำเสมอทุกที่ */
sub, sup {
  font-size: .72em;
  line-height: 0;
  position: relative;
  vertical-align: baseline;
  font-style: normal;
}
sup { top: -.5em; }
sub { bottom: -.28em; }
sub var, sup var { font-style: italic; }
/* ตัวห้อยตามด้วยตัวยก (เช่น V₂²) ให้ตัวยกชิดขึ้น */
sub + sup { margin-left: -.05em; }

/* ---------------- Tables ---------------- */
.table-wrap { overflow-x: auto; margin: 1.1em 0; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
table { border-collapse: collapse; width: 100%; font-size: 15px; line-height: 1.55; }
th, td { padding: 9px 12px; text-align: left; vertical-align: top; border-bottom: 1px solid var(--border); }
th { background: var(--surface-2); font-weight: 600; white-space: nowrap; }
tr:last-child td { border-bottom: none; }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
td.mono { font-family: var(--mono); font-size: 14px; }
tr.hl td { background: var(--accent-soft); }

/* ---------------- Figures ---------------- */
figure {
  margin: 1.4em 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  text-align: center;
  overflow-x: auto;
}
figure svg { display: block; margin: 0 auto; height: auto; color: var(--text); }
figcaption { font-size: 14px; color: var(--text-muted); margin-top: 8px; }
/* รูปประกอบจากแหล่งภายนอก */
figure.photo img {
  display: block;
  margin: 0 auto;
  max-height: 340px;
  width: auto;
  border-radius: 6px;
  background: #fff;           /* แผนภาพโปร่งใสต้องมีพื้นขาว อ่านได้ทั้งโหมดสว่างและมืด */
}
figure.photo.diagram img { padding: 8px; }
figure.photo.wide img { max-height: none; width: 100%; }
figcaption .credit { display: block; font-size: 12.5px; margin-top: 3px; opacity: .85; }
figcaption .credit a { color: inherit; }
.cite { font-size: .75em; vertical-align: super; line-height: 0; text-decoration: none; }

.refs { font-size: 15px; line-height: 1.6; }
.refs li { margin: .45em 0; overflow-wrap: anywhere; }
.refs .lic { color: var(--text-muted); }

.fig-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 16px; }
.fig-row figure { margin: 0; }

svg .wire { fill: none; stroke: currentColor; stroke-width: 2; stroke-linejoin: round; stroke-linecap: round; }
svg .comp { fill: var(--surface); stroke: currentColor; stroke-width: 2; stroke-linejoin: round; }
svg .dot { fill: currentColor; }
svg .term { fill: var(--surface); stroke: currentColor; stroke-width: 2; }
svg .lbl { fill: currentColor; font-family: var(--font); font-size: 15px; }
svg .lbl-sm { fill: var(--text-muted); font-family: var(--font); font-size: 13px; }
svg .accent { stroke: var(--accent); }
svg .accent-fill { fill: var(--accent); }
svg .bad-fill { fill: var(--bad); }
svg .dash { fill: none; stroke: var(--warn); stroke-width: 2; stroke-dasharray: 6 5; }
svg .grid { stroke: var(--border); stroke-width: 1; }

/* Measurement chain (HTML blocks) */
.chain { display: flex; flex-wrap: wrap; align-items: stretch; gap: 8px; margin: 1.2em 0; }
.chain .stage {
  flex: 1 1 140px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-top: 4px solid var(--accent);
  border-radius: var(--radius);
  padding: 10px 12px;
  font-size: 15px;
  line-height: 1.5;
}
.chain .stage b { display: block; font-size: 16px; }
.chain .stage small { color: var(--text-muted); }
.chain .arrow { align-self: center; color: var(--accent); font-size: 22px; font-weight: 700; }

/* ---------------- Cards (index) ---------------- */
.hero {
  background: linear-gradient(135deg, var(--accent-soft), var(--surface) 70%);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 36px 32px;
}
.hero h1 { font-size: 2.3rem; margin-bottom: .2em; }
.hero p { font-size: 1.1rem; color: var(--text-muted); max-width: 40em; }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; margin: 1.4em 0; }
.card {
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 20px 20px 16px;
  text-decoration: none;
  color: var(--text);
  box-shadow: var(--shadow);
  transition: border-color .15s, transform .15s;
}
.card:hover { border-color: var(--accent); transform: translateY(-2px); color: var(--text); }
.card .num { font-family: var(--mono); font-size: 13px; color: var(--accent); }
.card h3 { margin: .3em 0 .4em; font-size: 1.2rem; }
.card p { margin: 0; font-size: 15px; color: var(--text-muted); flex: 1; }
.card .go { margin-top: 12px; font-size: 14px; font-weight: 600; color: var(--accent); }

/* ---------------- Exercises ---------------- */
.quiz {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 8px 22px 20px;
  margin: 1.2em 0;
}
.q {
  padding: 16px 0;
  border-bottom: 1px dashed var(--border);
}
.q:last-of-type { border-bottom: none; }
.q .q-text { margin: 0 0 .5em; font-weight: 600; }
.q .q-text .qn { color: var(--accent); font-family: var(--mono); margin-right: .4em; }
.q label.opt {
  display: block;
  position: relative;
  padding: 7px 12px 7px 38px;
  margin: 4px 0;
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  line-height: 1.55;
}
.q label.opt:hover { background: var(--surface-2); }
.q label.opt input { position: absolute; left: 12px; top: calc(7px + .775em - 6.5px); margin: 0; accent-color: var(--accent); }
.q label.opt.correct { border-color: var(--ok); background: var(--accent-soft); }
.q label.opt.wrong { border-color: var(--bad); background: var(--bad-soft); }
.q .num-input { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.q .num-input input {
  font: inherit;
  width: 10em;
  padding: 6px 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--text);
}
.q .num-input input.correct { border-color: var(--ok); background: var(--accent-soft); }
.q .num-input input.wrong { border-color: var(--bad); background: var(--bad-soft); }
.q .explain {
  margin-top: 10px;
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--surface-2);
  font-size: 15px;
}
.q .explain .verdict { font-weight: 700; margin-right: .4em; }
.q .explain .verdict.ok { color: var(--ok); }
.q .explain .verdict.no { color: var(--bad); }

.quiz-actions { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin-top: 16px; }
.btn {
  font: inherit;
  font-weight: 600;
  font-size: 15px;
  padding: 8px 18px;
  border-radius: 8px;
  border: 1px solid var(--accent);
  background: var(--accent);
  color: #fff;
  cursor: pointer;
}
.btn:hover { filter: brightness(1.08); }
.btn.ghost { background: transparent; color: var(--accent); }
.score { font-weight: 700; font-size: 16px; }

details.solution {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin: 1em 0;
  padding: 0 18px;
}
details.solution > summary {
  cursor: pointer;
  padding: 12px 0;
  font-weight: 600;
  list-style: none;
}
details.solution > summary::-webkit-details-marker { display: none; }
details.solution > summary::before { content: "▸ "; color: var(--accent); }
details.solution[open] > summary::before { content: "▾ "; }
details.solution .problem { font-weight: 400; }
details.solution .sol { border-top: 1px dashed var(--border); padding: 4px 0 14px; }

.assignment {
  border: 2px dashed var(--warn);
  border-radius: 14px;
  padding: 16px 22px;
  background: var(--warn-soft);
  margin: 1.4em 0;
}
.assignment h3 { margin-top: .2em; }

/* ---------------- Pager ---------------- */
.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 48px; flex-wrap: wrap; }
.pager a {
  flex: 1 1 220px;
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: var(--radius);
  padding: 12px 16px;
  text-decoration: none;
  color: var(--text);
}
.pager a:hover { border-color: var(--accent); }
.pager a small { display: block; color: var(--text-muted); font-size: 13px; }
.pager a.next { text-align: right; }

/* ---------------- Responsive ---------------- */
@media (max-width: 960px) {
  .sidebar { transform: translateX(-100%); box-shadow: 4px 0 24px rgba(0,0,0,.3); }
  body.nav-open .sidebar { transform: none; }
  body.nav-open .sidebar-backdrop { display: block; }
  .page { margin-left: 0; }
  .menu-btn { display: inline-block; }
}
@media (max-width: 600px) {
  body { font-size: 16px; }
  h1 { font-size: 1.7rem; }
  .hero { padding: 24px 20px; }
  .hero h1 { font-size: 1.8rem; }
  .chapter-head { padding: 20px 18px 16px; }
  .content { padding: 22px 16px 40px; }
  .topbar { padding: 8px 16px; }
  .quiz { padding: 4px 14px 16px; }
  .chain .arrow { transform: rotate(90deg); flex-basis: 100%; text-align: center; }
}

@media print {
  .sidebar, .topbar, .sidebar-backdrop, .pager, .quiz-actions { display: none !important; }
  .page { margin-left: 0; }
  details.solution { break-inside: avoid; }
}