/* ==========================================================================
   learnbiostats — site.css
   Clean, readable styling for the learning-in-public site.

   Design principles applied throughout:
   - Clear visual hierarchy (type scale, spacing rhythm, one accent color).
   - Low cognitive load (generous whitespace, max line length ~70ch, few colors).
   - Colorblind-safe palette (Okabe-Ito) reused in CSS and in the D3 viz so the
     site and the charts speak the same visual language.
   - Preattentive emphasis reserved for the single most important element on a
     view (the primary call-to-action / the annotated focus point in a chart).
   ========================================================================== */

/* --- Color tokens: Okabe-Ito colorblind-safe palette ---------------------- */
:root {
  /* Okabe-Ito qualitative palette (safe for deuteranopia/protanopia/tritanopia) */
  --c-black:        #000000;
  --c-orange:       #E69F00;
  --c-skyblue:      #56B4E9;
  --c-bluishgreen:  #009E73;
  --c-yellow:       #F0E442;
  --c-blue:         #0072B2;
  --c-vermillion:   #D55E00;
  --c-reddishpurple:#CC79A7;

  /* Semantic roles */
  --ink:        #1a1f24;   /* primary text */
  --ink-soft:   #4a5560;   /* secondary text */
  --ink-faint:  #75828d;   /* captions, metadata */
  --paper:      #ffffff;   /* page background */
  --paper-2:    #f6f8fa;   /* card / panel background */
  --rule:       #e3e8 ec;  /* hairline borders (overridden below) */
  --rule:       #e3e8ec;
  --accent:     var(--c-blue);        /* primary accent / CTA */
  --accent-2:   var(--c-vermillion);  /* preattentive "focus" highlight */
  --link:       var(--c-blue);
  --link-hover: #005a8c;

  /* Type + spacing */
  --maxw:       72ch;
  --maxw-wide:  1040px;
  --radius:     10px;
  --shadow:     0 1px 2px rgba(16,24,40,.06), 0 1px 3px rgba(16,24,40,.10);
  --font-body:  -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono:  ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

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

html { -webkit-text-size-adjust: 100%; }

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

/* --- Layout containers ---------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: 1.25rem;
}
.container-wide { max-width: var(--maxw-wide); }

/* --- Skip link for keyboard users ---------------------------------------- */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--accent);
  color: #fff;
  padding: .5rem .9rem;
  border-radius: 0 0 var(--radius) 0;
  z-index: 100;
}
.skip-link:focus { left: 0; }

/* --- Visual hierarchy: typography ---------------------------------------- */
h1, h2, h3 { line-height: 1.2; color: var(--ink); font-weight: 700; }
h1 { font-size: clamp(1.9rem, 1.3rem + 2.4vw, 2.7rem); margin: 0 0 .4rem; letter-spacing: -.01em; }
h2 { font-size: clamp(1.35rem, 1.1rem + 1.1vw, 1.7rem); margin: 2.4rem 0 .8rem; }
h3 { font-size: 1.15rem; margin: 1.6rem 0 .5rem; }

p  { margin: 0 0 1rem; max-width: var(--maxw); }
.lead { font-size: 1.18rem; color: var(--ink-soft); }

small, .meta { color: var(--ink-faint); font-size: .9rem; }

a { color: var(--link); text-decoration: underline; text-underline-offset: 2px; }
a:hover { color: var(--link-hover); }
a:focus-visible { outline: 3px solid var(--c-skyblue); outline-offset: 2px; border-radius: 3px; }

code, kbd { font-family: var(--font-mono); font-size: .92em; }
code { background: var(--paper-2); padding: .1em .35em; border-radius: 5px; }

/* --- Site header --------------------------------------------------------- */
.site-header {
  border-bottom: 1px solid var(--rule);
  background: var(--paper);
}
.site-header .container {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 1rem;
  flex-wrap: wrap;
}
.site-title { font-weight: 800; font-size: 1.15rem; letter-spacing: -.01em; text-decoration: none; color: var(--ink); }
.site-title span { color: var(--accent); }
.site-nav { display: flex; gap: 1.1rem; flex-wrap: wrap; }
.site-nav a { text-decoration: none; color: var(--ink-soft); font-size: .98rem; }
.site-nav a:hover { color: var(--accent); }

/* --- Hero ---------------------------------------------------------------- */
.hero { padding-block: 2.6rem 1.4rem; }
.hero .lead { margin-bottom: 1.4rem; }

/* --- Buttons: preattentive emphasis on the ONE primary action ------------ */
.btn {
  display: inline-block;
  font-weight: 600;
  text-decoration: none;
  padding: .65rem 1.1rem;
  border-radius: var(--radius);
  border: 1px solid transparent;
  transition: background-color .15s ease, transform .05s ease;
}
.btn:active { transform: translateY(1px); }
.btn-primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.btn-primary:hover { background: var(--link-hover); color: #fff; }
.btn-secondary {
  background: var(--paper);
  color: var(--accent);
  border-color: var(--accent);
}
.btn-secondary:hover { background: var(--paper-2); }
.btn-row { display: flex; gap: .75rem; flex-wrap: wrap; margin: 1.2rem 0; }

/* --- Cards: posts list --------------------------------------------------- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1rem;
  margin: 1rem 0 0;
  padding: 0;
  list-style: none;
}
.card {
  background: var(--paper-2);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: 1.1rem 1.2rem;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: .35rem;
}
.card h3 { margin: 0; font-size: 1.08rem; }
.card h3 a { text-decoration: none; }
.card h3 a:hover { text-decoration: underline; }
.card .meta { margin: 0; }
.card p { margin: .25rem 0 0; font-size: .96rem; color: var(--ink-soft); }
.card.placeholder {
  border-style: dashed;
  background: repeating-linear-gradient(
    -45deg, var(--paper-2), var(--paper-2) 12px, #eef1f4 12px, #eef1f4 24px);
}
.card .tag {
  align-self: flex-start;
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--accent-2);
  background: #fff;
  border: 1px solid var(--accent-2);
  border-radius: 999px;
  padding: .1rem .55rem;
}

/* --- Callout / note panel ------------------------------------------------ */
.callout {
  border: 1px solid var(--rule);
  border-left: 4px solid var(--accent);
  background: var(--paper-2);
  border-radius: var(--radius);
  padding: 1rem 1.15rem;
  margin: 1.4rem 0;
}
.callout p:last-child { margin-bottom: 0; }

/* ==========================================================================
   Visualization page
   ========================================================================== */
.viz-page main { padding-bottom: 3rem; }

.viz-figure {
  margin: 1.5rem 0 0;
  background: var(--paper);
}

/* The takeaway title sits ABOVE the chart and states the insight, not the topic. */
.viz-takeaway {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--ink);
  margin: 0 0 .15rem;
}
.viz-subhead { color: var(--ink-soft); margin: 0 0 1rem; font-size: 1rem; }

/* "How to read it" caption — keeps cognitive load low by teaching the encoding. */
.viz-caption {
  font-size: .95rem;
  color: var(--ink-soft);
  background: var(--paper-2);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: .85rem 1rem;
  margin: 0 0 1.4rem;
}
.viz-caption strong { color: var(--ink); }

/* Control panels for sliders / buttons */
.controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem 1.5rem;
  align-items: end;
  background: var(--paper-2);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: 1rem 1.15rem;
  margin: 1rem 0 1.4rem;
}
.control { display: flex; flex-direction: column; gap: .35rem; }
.control label { font-weight: 600; font-size: .95rem; }
.control .val { font-variant-numeric: tabular-nums; color: var(--accent); font-weight: 700; }
.control input[type="range"] { width: 100%; accent-color: var(--accent); }
.control-buttons { display: flex; gap: .5rem; flex-wrap: wrap; align-items: end; }

/* The chart SVGs */
.chart-wrap { width: 100%; overflow-x: auto; }
svg.chart { display: block; width: 100%; height: auto; font-family: var(--font-body); }

/* SVG text classes mirrored by the JS */
.axis text { fill: var(--ink-soft); font-size: 12px; }
.axis line, .axis path { stroke: #c9d1d9; shape-rendering: crispEdges; }
.axis-title { fill: var(--ink); font-size: 13px; font-weight: 600; }

.bar-label { fill: var(--ink); font-size: 13px; font-weight: 700; font-variant-numeric: tabular-nums; }
.annotation { fill: var(--ink-soft); font-size: 12px; }
.annotation-note { fill: var(--ink); font-size: 12.5px; font-weight: 600; }
.annotation-line { stroke: var(--ink-faint); stroke-width: 1; stroke-dasharray: 3 3; }

/* Two charts side by side on wide screens, stacked on narrow */
.viz-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
}
@media (min-width: 860px) {
  .viz-grid.cols-2 { grid-template-columns: 1fr 1fr; }
}

/* Legend shared by charts */
.legend { display: flex; gap: 1.1rem; flex-wrap: wrap; margin: .5rem 0 0; padding: 0; list-style: none; font-size: .9rem; color: var(--ink-soft); }
.legend li { display: flex; align-items: center; gap: .4rem; }
.legend .swatch { width: 14px; height: 14px; border-radius: 3px; display: inline-block; }

/* --- Footer -------------------------------------------------------------- */
.site-footer {
  border-top: 1px solid var(--rule);
  margin-top: 3rem;
  padding-block: 1.6rem 2.4rem;
  color: var(--ink-faint);
  font-size: .92rem;
}
.site-footer a { color: var(--ink-soft); }

/* --- Motion preference ---------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}