/* ==========================================================================
   Light Blue Design System — shared theme for all lessons and reference pages
   Workspace: teach / epidemiology (Farsi, RTL)
   Include with: <link rel="stylesheet" href="../assets/blue-theme.css">
   ========================================================================== */

@import url("https://fonts.googleapis.com/css2?family=Vazirmatn:wght@100..900&display=swap");

:root {
  --blue-950: #082f49; /* Tailwind sky-950 */
  --blue-800: #075985; /* Tailwind sky-800 */
  --blue-600: #0284c7; /* Tailwind sky-600 */
  --blue-400: #38bdf8; /* Tailwind sky-400 */
  --blue-200: #bae6fd; /* Tailwind sky-200 */
  --blue-100: #e0f2fe; /* Tailwind sky-100 */
  --blue-50: #f9fbfb; /* Tailwind gray-50 */
  --ink: #0f172a; /* Tailwind slate-900 */
  --white: #ffffff;
  --correct: #1a7f5a; /* quiz: correct */
  --incorrect: #b3402e; /* quiz: incorrect */

  --serif:
    "Vazirmatn", "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI",
    system-ui, sans-serif;
  --sans:
    "Vazirmatn", "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI",
    system-ui, sans-serif;
  --mono: "SFMono-Regular", Menlo, Consolas, monospace;

  --measure: 52rem;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(8, 47, 73, 0.06), 0 6px 24px rgba(8, 47, 73, 0.06);
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--blue-50);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

/* --- Header band ---------------------------------------------------------- */

.band {
  background: linear-gradient(135deg, var(--blue-950), var(--blue-800));
  color: var(--white);
  padding: 1.1rem 1.25rem;
}
.band__inner {
  max-width: var(--measure);
  margin: 0 auto;
}
.band__kicker {
  font-family: var(--sans);
  font-size: 0.74rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  opacity: 0.85;
}
.band__title {
  font-family: var(--sans);
  font-weight: 700;
  font-size: clamp(1.3rem, 4vw, 1.9rem);
  line-height: 1.25;
  margin: 0.25rem 0 0;
}
.band__part {
  display: inline-block;
  margin-top: 0.5rem;
  font-family: var(--sans);
  font-size: 0.8rem;
  background: rgba(255, 255, 255, 0.14);
  border: 1px solid rgba(255, 255, 255, 0.25);
  border-radius: 999px;
  padding: 0.15rem 0.7rem;
}

/* --- Layout --------------------------------------------------------------- */

.wrap {
  max-width: var(--measure);
  margin: 0 auto;
  padding: 1.75rem 1.25rem 4rem;
}

main > section {
  margin: 2.25rem 0;
}

h1,
h2,
h3,
h4 {
  font-family: var(--sans);
  color: var(--blue-950);
  line-height: 1.3;
}
h1 {
  font-size: 1.6rem;
}
h2 {
  font-size: 1.32rem;
  margin: 2rem 0 0.75rem;
  padding-bottom: 0.35rem;
  border-bottom: 2px solid var(--blue-200);
}
h3 {
  font-size: 1.1rem;
  margin: 1.5rem 0 0.5rem;
}
h4 {
  font-size: 0.98rem;
  margin: 1.25rem 0 0.4rem;
  color: var(--blue-800);
}

p {
  margin: 0.65rem 0;
}
ul,
ol {
  padding-inline-start: 1.5rem;
}
li {
  margin: 0.35rem 0;
}

a {
  color: var(--blue-800);
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}

strong {
  color: var(--blue-950);
}
em {
  font-style: italic;
}
.mark {
  color: var(--incorrect);
  font-weight: 700;
}

code,
kbd,
.term-en {
  font-family: var(--mono);
  font-size: 0.92em;
  direction: ltr;
  unicode-bidi: embed;
}
:not(pre) > code {
  background: var(--blue-100);
  border: 1px solid var(--blue-200);
  border-radius: 5px;
  padding: 0.05em 0.35em;
}

hr {
  border: none;
  border-top: 1px solid var(--blue-200);
  margin: 2rem 0;
}

/* --- From-your-class card ------------------------------------------------- */

.from-class {
  background: var(--blue-100);
  border-inline-start: 5px solid var(--blue-600);
  border-radius: var(--radius);
  padding: 0.9rem 1.1rem;
  font-family: var(--sans);
  font-size: 0.9rem;
  line-height: 1.55;
  margin: 1rem 0 1.75rem;
}
.from-class dl {
  margin: 0.3rem 0 0;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.15rem 0.6rem;
}
.from-class dt {
  color: var(--blue-800);
  font-weight: 600;
}
.from-class dd {
  margin: 0;
}

/* --- Callouts ------------------------------------------------------------- */

.callout {
  background: var(--blue-100);
  border: 1px solid var(--blue-200);
  border-radius: var(--radius);
  padding: 0.85rem 1.05rem;
  margin: 1.1rem 0;
}
.callout > .label {
  display: block;
  font-family: var(--sans);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--blue-800);
  margin-bottom: 0.3rem;
}
.callout p:first-of-type {
  margin-top: 0;
}
.callout p:last-child {
  margin-bottom: 0;
}

.callout--key {
  border-inline-start: 5px solid var(--blue-600);
}
.callout--exam {
  border-inline-start: 5px solid var(--blue-800);
  background: var(--white);
}
.callout--warn {
  border-inline-start: 5px solid var(--incorrect);
}
.callout--tip {
  border-inline-start: 5px solid var(--blue-400);
}
.callout--addition {
  border-style: dashed;
}

/* --- Side / margin note --------------------------------------------------- */

.margin-note {
  display: block;
  font-family: var(--sans);
  font-size: 0.82rem;
  line-height: 1.5;
  color: var(--blue-800);
  border-inline-start: 3px solid var(--blue-400);
  padding-inline-start: 0.7rem;
  margin: 0.7rem 0 1rem;
}
.margin-note .src {
  display: block;
  color: var(--ink);
  opacity: 0.75;
  font-size: 0.76rem;
  margin-top: 0.2rem;
}

/* --- Tables --------------------------------------------------------------- */

.table-scroll {
  overflow-x: auto;
  margin: 1.1rem 0;
}
table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--sans);
  font-size: 0.9rem;
}
caption {
  caption-side: top;
  text-align: start;
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--blue-800);
  padding-bottom: 0.4rem;
}
th,
td {
  border: 1px solid var(--blue-200);
  padding: 0.5rem 0.65rem;
  text-align: start;
  vertical-align: top;
}
thead th {
  background: var(--blue-800);
  color: var(--white);
  font-weight: 600;
}
tbody tr:nth-child(odd) {
  background: var(--blue-50);
}
tbody tr:nth-child(even) {
  background: var(--blue-100);
}

/* --- Contents ------------------------------------------------------------- */

.toc {
  background: var(--white);
  border: 1px solid var(--blue-200);
  border-radius: var(--radius);
  padding: 1rem 1.15rem;
  box-shadow: var(--shadow);
}
.toc h2 {
  margin-top: 0;
  border: none;
  font-size: 1rem;
}
.toc ol {
  margin: 0;
  padding-inline-start: 1.3rem;
  font-family: var(--sans);
  font-size: 0.9rem;
}
.toc a {
  color: var(--blue-800);
}

/* --- Part navigation ------------------------------------------------------ */

.partnav {
  display: flex;
  gap: 0.6rem;
  justify-content: space-between;
  align-items: stretch;
  margin: 1.25rem 0;
  font-family: var(--sans);
  font-size: 0.88rem;
}
.partnav a,
.partnav span {
  flex: 1 1 0;
  border: 1px solid var(--blue-200);
  border-radius: var(--radius);
  padding: 0.55rem 0.7rem;
  background: var(--white);
}
.partnav a:hover {
  border-color: var(--blue-600);
  text-decoration: none;
}
.partnav .dir {
  display: block;
  font-size: 0.72rem;
  color: var(--blue-800);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}
.partnav .next {
  text-align: end;
}
.partnav .disabled {
  opacity: 0.45;
}

/* --- Buttons -------------------------------------------------------------- */

.btn {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.9rem;
  font-weight: 600;
  background: var(--blue-800);
  color: var(--white);
  border: 1px solid var(--blue-800);
  border-radius: 999px;
  padding: 0.45rem 1.1rem;
  cursor: pointer;
}
.btn:hover {
  background: var(--blue-600);
  border-color: var(--blue-600);
  text-decoration: none;
}
.btn:focus-visible {
  outline: 3px solid var(--blue-400);
  outline-offset: 2px;
}
.btn--ghost {
  background: transparent;
  color: var(--blue-800);
}
.btn--ghost:hover {
  background: var(--blue-100);
}

/* --- Quiz widget ---------------------------------------------------------- */

.quiz {
  background: var(--white);
  border: 1px solid var(--blue-200);
  border-radius: var(--radius);
  padding: 1rem 1.15rem;
  margin: 1.2rem 0;
  box-shadow: var(--shadow);
}
.quiz h3 {
  margin-top: 0;
}
.quiz__q {
  font-family: var(--sans);
  font-weight: 600;
  color: var(--blue-950);
  margin: 0.2rem 0 0.6rem;
}
.quiz__opts {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.45rem;
}
.quiz__opts li {
  margin: 0;
}
.quiz__opt {
  width: 100%;
  text-align: start;
  font-family: var(--sans);
  font-size: 0.9rem;
  background: var(--blue-50);
  color: var(--ink);
  border: 1px solid var(--blue-200);
  border-radius: 8px;
  padding: 0.55rem 0.8rem;
  cursor: pointer;
}
.quiz__opt:hover:not(:disabled) {
  border-color: var(--blue-600);
  background: var(--blue-100);
}
.quiz__opt:focus-visible {
  outline: 3px solid var(--blue-400);
  outline-offset: 1px;
}
.quiz__opt[aria-pressed="true"] {
  border-color: var(--blue-400);
  background: var(--blue-100);
}
.quiz__opt.is-correct {
  border-color: var(--correct);
  background: #e4f5ee;
  color: var(--correct);
  font-weight: 600;
}
.quiz__opt.is-incorrect {
  border-color: var(--incorrect);
  background: #fbe9e6;
  color: var(--incorrect);
}
.quiz__opt:disabled {
  cursor: default;
}
.quiz__fb {
  font-family: var(--sans);
  font-size: 0.86rem;
  line-height: 1.5;
  margin-top: 0.6rem;
  padding: 0.55rem 0.75rem;
  border-radius: 8px;
  display: none;
}
.quiz__fb.show {
  display: block;
}
.quiz__fb.ok {
  background: #e4f5ee;
  color: var(--correct);
  border: 1px solid var(--correct);
}
.quiz__fb.no {
  background: #fbe9e6;
  color: var(--incorrect);
  border: 1px solid var(--incorrect);
}
.quiz__fb .src {
  display: block;
  margin-top: 0.3rem;
  font-size: 0.78rem;
  opacity: 0.85;
}

/* Fill-in-the-blank */
.blank {
  font-family: var(--mono);
  font-size: 0.95rem;
  direction: ltr;
  border: none;
  border-bottom: 2px dashed var(--blue-400);
  background: transparent;
  color: var(--blue-800);
  text-align: center;
  min-width: 7rem;
  padding: 0.05rem 0.3rem;
}
.blank:focus {
  outline: none;
  border-bottom-style: solid;
}
.blank.is-correct {
  color: var(--correct);
  border-bottom-color: var(--correct);
}
.blank.is-incorrect {
  color: var(--incorrect);
  border-bottom-color: var(--incorrect);
}

/* Reveal-in-your-own-words */
.reveal {
  border: 1px dashed var(--blue-400);
  border-radius: var(--radius);
  padding: 0.7rem 0.9rem;
  background: var(--blue-50);
  margin: 0.8rem 0;
}
.reveal > summary {
  font-family: var(--sans);
  font-weight: 600;
  color: var(--blue-800);
  cursor: pointer;
}
.reveal[open] > summary {
  margin-bottom: 0.4rem;
}

/* --- Footer --------------------------------------------------------------- */

.footer {
  max-width: var(--measure);
  margin: 0 auto;
  padding: 1.5rem 1.25rem 3rem;
  font-family: var(--sans);
  font-size: 0.84rem;
  color: var(--blue-800);
  border-top: 1px solid var(--blue-200);
}

/* --- Reference page helpers ---------------------------------------------- */

.ref-grid {
  display: grid;
  gap: 0.9rem;
  grid-template-columns: 1fr;
}
@media (min-width: 40rem) {
  .ref-grid {
    grid-template-columns: 1fr 1fr;
  }
}
.card {
  background: var(--white);
  border: 1px solid var(--blue-200);
  border-radius: var(--radius);
  padding: 0.9rem 1.05rem;
  box-shadow: var(--shadow);
}
.card h3 {
  margin-top: 0;
}
dl.terms {
  margin: 0;
}
dl.terms dt {
  font-family: var(--sans);
  font-weight: 700;
  color: var(--blue-800);
  margin-top: 0.7rem;
}
dl.terms dd {
  margin: 0.1rem 0 0;
}
.badge {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  background: var(--blue-100);
  color: var(--blue-800);
  border: 1px solid var(--blue-200);
  border-radius: 999px;
  padding: 0.05rem 0.5rem;
  margin-inline-start: 0.35rem;
  vertical-align: middle;
}

/* --- Long-page contents sidebar ------------------------------------------ */

@media (min-width: 68rem) {
  .layout {
    display: grid;
    grid-template-columns: minmax(0, var(--measure)) 15rem;
    gap: 2.5rem;
    max-width: 62rem;
    margin: 0 auto;
    align-items: start;
  }
  .layout .wrap {
    margin: 0;
  }
  .layout .toc {
    position: sticky;
    top: 1.25rem;
    grid-column: 2;
    grid-row: 1;
  }
}

/* --- Dark mode ------------------------------------------------------------ */

/* @media (prefers-color-scheme: dark) {
  :root {
    --blue-50:  #082f49;
    --blue-100: #0c4a6e;
    --blue-200: #075985;
    --blue-400: #38bdf8;
    --ink:      #e0f2fe;
    --white:    #082f49;
    --blue-950: #f0f9ff;
    --blue-800: #7dd3fc;
    --correct:  #56c79a;
    --incorrect:#f08a76;
  }
  .band { background: linear-gradient(135deg, #082f49, #075985); }
  .band__title, .band__kicker { color: #f0f9ff; }
  .card, .quiz, .toc, .partnav a, .partnav span { box-shadow: none; }
  .quiz__opt.is-correct { background: #10352a; }
  .quiz__opt.is-incorrect { background: #3a1c17; }
  .quiz__fb.ok { background: #10352a; }
  .quiz__fb.no { background: #3a1c17; }
  thead th { background: #075985; color: #f0f9ff; }
} */

/* --- Print ---------------------------------------------------------------- */

@media print {
  :root {
    --blue-50: #fff;
    --blue-100: #f3f7fd;
    --blue-200: #9db9dd;
    --ink: #000;
    --white: #fff;
  }
  body {
    background: #fff;
    color: #000;
    font-size: 11pt;
  }
  .band {
    background: none;
    color: #000;
    border-bottom: 2px solid var(--blue-800);
  }
  .band__title,
  .band__kicker {
    color: #000;
  }
  .band__part {
    border-color: #666;
    background: none;
    color: #000;
  }
  .partnav,
  .btn,
  .toc {
    display: none;
  }
  a {
    color: #000;
    text-decoration: none;
  }
  h2 {
    color: var(--blue-800);
  }
  h3,
  h4 {
    color: #000;
  }
  .callout,
  .quiz,
  .card,
  .from-class,
  table,
  tr,
  .margin-note,
  .reveal {
    break-inside: avoid;
    page-break-inside: avoid;
  }
  thead th {
    background: none;
    color: #000;
    border-bottom: 2px solid #000;
  }
  .quiz__opt {
    border-color: #999;
  }
  .quiz__fb {
    display: block !important;
  }
}