/* ---------------------------------------------------------------
   Paul's Python Course
   Paper + deep teal. One accent, used only on things you can touch.
   --------------------------------------------------------------- */

:root {
  color-scheme: light;

  --bg:          #f6f5f2;
  --bg-raised:   #fffefc;
  --tint:        #edece6;   /* code backgrounds, quiet fills */
  --tint-strong: #e4e2da;

  --ink:   #1b1a17;
  --ink-2: #45433d;
  --ink-3: #66635a;

  --rule:        #dddbd3;
  --rule-strong: #c6c3b8;

  --accent:      #0d635e;
  --accent-hover:#0a4d49;
  --accent-tint: #dcebe8;

  --bad:      #a3271d;
  --bad-tint: #f6e6e3;
  --good:      #2c6337;
  --good-tint: #e2eee3;

  --sans: "IBM Plex Sans", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --display: "Bricolage Grotesque", var(--sans);
  --mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;

  --measure: 68ch;
  --radius: 4px;
  --page-x: clamp(1.15rem, 5vw, 3rem);
  --header-h: 3.5rem;
}

:root[data-theme="dark"],
:root:not([data-theme="light"]) {
  /* placeholder so the cascade order below is predictable */
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg:          #15181a;
    --bg-raised:   #1b1f21;
    --tint:        #21262a;
    --tint-strong: #2b3136;
    --ink:   #e9e7e1;
    --ink-2: #b6b3ab;
    --ink-3: #98958e;
    --rule:        #2c3236;
    --rule-strong: #414850;
    --accent:      #57c8bb;
    --accent-hover:#7fdcd0;
    --accent-tint: #14312f;
    --bad:      #f0938a;
    --bad-tint: #33201e;
    --good:      #8ecb98;
    --good-tint: #1c2c20;
  }
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg:          #15181a;
  --bg-raised:   #1b1f21;
  --tint:        #21262a;
  --tint-strong: #2b3136;
  --ink:   #e9e7e1;
  --ink-2: #b6b3ab;
  --ink-3: #98958e;
  --rule:        #2c3236;
  --rule-strong: #414850;
  --accent:      #57c8bb;
  --accent-hover:#7fdcd0;
  --accent-tint: #14312f;
  --bad:      #f0938a;
  --bad-tint: #33201e;
  --good:      #8ecb98;
  --good-tint: #1c2c20;
}

/* --- reset-ish ------------------------------------------------- */

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

/* several components set display, which would otherwise beat the UA rule */
[hidden] { display: none !important; }

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

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1.0625rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 {
  font-family: var(--display);
  font-weight: 600;
  line-height: 1.18;
  letter-spacing: -0.018em;
  margin: 0;
  text-wrap: balance;
}

p { margin: 0 0 1em; }
p:last-child { margin-bottom: 0; }

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}
a:hover { color: var(--accent-hover); }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 2px;
}

code, kbd, samp, pre { font-family: var(--mono); }

hr {
  border: 0;
  border-top: 1px solid var(--rule);
  margin: 3rem 0;
}

.skip-link {
  position: absolute;
  left: 0.5rem;
  top: -4rem;
  z-index: 60;
  background: var(--bg-raised);
  border: 1px solid var(--rule-strong);
  padding: 0.5rem 0.85rem;
  border-radius: var(--radius);
  transition: top 0.15s ease;
}
.skip-link:focus { top: 0.5rem; }

.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0);
  white-space: nowrap; border: 0;
}

/* --- shell ----------------------------------------------------- */

.wrap {
  width: 100%;
  max-width: 64rem;
  margin: 0 auto;
  padding-inline: var(--page-x);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  backdrop-filter: saturate(1.6) blur(8px);
  border-bottom: 1px solid var(--rule);
}

.site-header .wrap {
  height: var(--header-h);
  display: flex;
  align-items: center;
  gap: 1rem;
}

.brand {
  font-family: var(--display);
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: -0.01em;
  color: var(--ink);
  text-decoration: none;
  margin-right: auto;
}
.brand:hover { color: var(--ink); }
.brand .brand-dot {
  display: inline-block;
  width: 0.4rem; height: 0.4rem;
  background: var(--accent);
  margin-right: 0.5rem;
  vertical-align: 0.12em;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.header-link {
  font-size: 0.875rem;
  color: var(--ink-2);
  text-decoration: none;
  padding: 0.35rem 0.55rem;
  border-radius: var(--radius);
}
.header-link:hover { color: var(--ink); background: var(--tint); }
.header-link[aria-current="page"] { color: var(--ink); font-weight: 500; }

/* four nav items plus the wordmark is a tight fit on a phone */
@media (max-width: 34rem) {
  .site-header .wrap { gap: 0.4rem; }
  .brand { font-size: 0.82rem; white-space: nowrap; }
  .header-link { font-size: 0.8rem; padding: 0.35rem 0.28rem; }
  .header-nav { gap: 0.1rem; }
  .btn-icon { padding: 0.4rem; }
}
@media (max-width: 24rem) {
  .brand .brand-long { display: none; }
}

/* --- buttons --------------------------------------------------- */

.btn {
  font: inherit;
  font-size: 0.875rem;
  font-weight: 500;
  line-height: 1;
  color: var(--ink);
  background: var(--bg-raised);
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius);
  padding: 0.55rem 0.85rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  text-decoration: none;
  transition: background 0.14s ease, border-color 0.14s ease, color 0.14s ease;
}
.btn:hover { border-color: var(--ink-3); background: var(--tint); }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }
.btn:disabled:hover { background: var(--bg-raised); border-color: var(--rule-strong); }

.btn-primary {
  color: var(--bg-raised);
  background: var(--accent);
  border-color: var(--accent);
}
.btn-primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); color: var(--bg-raised); }
:root[data-theme="dark"] .btn-primary,
:root[data-theme="dark"] .btn-primary:hover { color: #10201f; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .btn-primary,
  :root:not([data-theme="light"]) .btn-primary:hover { color: #10201f; }
}

.btn-quiet {
  background: transparent;
  border-color: transparent;
  color: var(--ink-2);
  padding-inline: 0.5rem;
}
.btn-quiet:hover { background: var(--tint); border-color: transparent; color: var(--ink); }

.btn-icon { padding: 0.45rem; }

.btn .icon { width: 15px; height: 15px; flex: none; }

.icon {
  width: 16px; height: 16px;
  stroke: currentColor;
  stroke-width: 1.6;
  fill: none;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* --- home ------------------------------------------------------ */

.intro {
  padding: clamp(2.75rem, 8vw, 4.5rem) 0 2rem;
  max-width: var(--measure);
}
.intro h1 {
  font-size: clamp(2rem, 6vw, 2.9rem);
  margin-bottom: 0.6rem;
}
.intro p {
  color: var(--ink-2);
  font-size: 1.09rem;
  margin: 0;
}
.intro .continue { margin-top: 1.75rem; }
.intro .continue:empty { margin-top: 0; }

.section-label {
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin: 0 0 1rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid var(--rule);
}

.lesson-list {
  list-style: none;
  margin: 0 0 3.5rem;
  padding: 0;
}

.lesson-card {
  border-bottom: 1px solid var(--rule);
}

.lesson-card > a,
.lesson-card > div {
  display: grid;
  grid-template-columns: 3.25rem 1fr;
  gap: 0 1.25rem;
  padding: 1.5rem 0;
  text-decoration: none;
  color: inherit;
}
.lesson-card > a { transition: background 0.14s ease; }
.lesson-card > a:hover { background: var(--tint); }
.lesson-card > a:hover .lesson-title { color: var(--accent); }
.lesson-card > a:hover .lesson-index { color: var(--accent); }

.lesson-index {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--ink-3);
  padding-top: 0.3rem;
  transition: color 0.14s ease;
}

.lesson-title {
  font-family: var(--display);
  font-size: 1.3rem;
  font-weight: 600;
  letter-spacing: -0.015em;
  margin: 0 0 0.25rem;
  transition: color 0.14s ease;
}

.lesson-summary { color: var(--ink-2); margin: 0; font-size: 0.97rem; }

.lesson-card.is-locked > div { opacity: 0.62; }
.lesson-card.is-locked .lesson-title { font-weight: 500; }

.tag {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--ink-3);
  border: 1px solid var(--rule-strong);
  border-radius: 2px;
  padding: 0.1rem 0.4rem;
  vertical-align: 0.15em;
  margin-left: 0.5rem;
  white-space: nowrap;
}

.progress {
  margin-top: 0.9rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}
.progress-track {
  position: relative;
  height: 3px;
  flex: 1 1 8rem;
  min-width: 6rem;
  max-width: 14rem;
  background: var(--tint-strong);
}
.progress-fill {
  position: absolute;
  inset: 0 auto 0 0;
  background: var(--accent);
  transition: width 0.2s ease;
}
.progress-count {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--ink-3);
  white-space: nowrap;
}

/* --- lesson layout --------------------------------------------- */

.lesson-head {
  padding: clamp(2.25rem, 6vw, 3.5rem) 0 1.75rem;
  border-bottom: 1px solid var(--rule);
}
.lesson-eyebrow {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin: 0 0 0.7rem;
}
.lesson-head h1 {
  font-size: clamp(1.9rem, 5.5vw, 2.7rem);
  max-width: 20ch;
}
.lesson-head .lede {
  margin: 0.75rem 0 0;
  color: var(--ink-2);
  max-width: var(--measure);
}

.lesson-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
  padding-bottom: 4rem;
}

@media (min-width: 62rem) {
  .lesson-layout {
    grid-template-columns: 14.5rem minmax(0, 1fr);
    gap: 3.5rem;
    align-items: start;
  }
}

.sidebar { min-width: 0; }

@media (min-width: 62rem) {
  .sidebar {
    position: sticky;
    top: calc(var(--header-h) + 1.5rem);
    max-height: calc(100vh - var(--header-h) - 3rem);
    overflow-y: auto;
    padding: 2.25rem 0 1rem;
    border-right: 1px solid var(--rule);
    padding-right: 1.25rem;
  }
  .sidebar-toggle { display: none; }
}

.sidebar h2 {
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin: 0 0 0.7rem;
}

.objectives {
  margin: 0 0 2rem;
  padding: 0 0 0 1.05rem;
  color: var(--ink-2);
  font-size: 0.9rem;
  line-height: 1.5;
}
.objectives li { margin-bottom: 0.45rem; }
.objectives li::marker { color: var(--ink-3); }

.toc { list-style: none; margin: 0; padding: 0; }
.toc li { margin: 0; }
.toc a {
  display: block;
  font-size: 0.875rem;
  color: var(--ink-2);
  text-decoration: none;
  padding: 0.3rem 0 0.3rem 0.7rem;
  border-left: 2px solid var(--rule);
  transition: color 0.14s ease, border-color 0.14s ease;
}
.toc a:hover { color: var(--ink); border-left-color: var(--rule-strong); }
.toc a.is-current {
  color: var(--accent);
  border-left-color: var(--accent);
  font-weight: 500;
}

/* mobile: sidebar collapses into a disclosure under the header */
.sidebar-panel { display: block; }

@media (max-width: 61.99rem) {
  .sidebar {
    position: sticky;
    top: var(--header-h);
    z-index: 30;
    background: var(--bg);
    border-bottom: 1px solid var(--rule);
    margin-inline: calc(var(--page-x) * -1);
    padding-inline: var(--page-x);
  }
  .sidebar-toggle {
    width: 100%;
    justify-content: space-between;
    border: 0;
    background: transparent;
    padding: 0.85rem 0;
    font-size: 0.875rem;
    color: var(--ink-2);
    border-radius: 0;
  }
  .sidebar-toggle:hover { background: transparent; color: var(--ink); }
  .sidebar-toggle .icon { transition: transform 0.16s ease; }
  .sidebar-toggle[aria-expanded="true"] .icon { transform: rotate(180deg); }
  .sidebar-panel { display: none; padding-bottom: 1.25rem; }
  .sidebar-panel.is-open { display: block; }
  .sidebar h2 { margin-top: 0.5rem; }
}

.lesson-body { min-width: 0; padding-top: 2.25rem; }

.lesson-section {
  max-width: var(--measure);
  margin-bottom: 3.25rem;
  scroll-margin-top: calc(var(--header-h) + 4rem);
}
.lesson-section > h2 {
  font-size: 1.45rem;
  margin-bottom: 0.8rem;
}
.lesson-section > h2 .sec-num {
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 400;
  letter-spacing: 0.06em;
  color: var(--ink-3);
  display: block;
  margin-bottom: 0.4rem;
}
.lesson-section p { color: var(--ink-2); }
.lesson-section .explain {
  font-size: 0.94rem;
  color: var(--ink-3);
  margin-top: 0.85rem;
}

.callout {
  border-left: 2px solid var(--accent);
  background: var(--accent-tint);
  padding: 1.1rem 1.25rem;
  border-radius: 0 var(--radius) var(--radius) 0;
}
.callout h2 { font-size: 1.15rem; margin-bottom: 0.6rem; }
.callout p { color: var(--ink-2); }

/* --- mistake blocks -------------------------------------------- */

.mistake-pair {
  display: grid;
  gap: 1rem;
  margin: 1.1rem 0;
}
@media (min-width: 34rem) {
  .mistake-pair { grid-template-columns: 1fr 1fr; }
}
.mistake-col h3 {
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin: 0 0 0.4rem;
  display: flex;
  align-items: center;
  gap: 0.35rem;
}
.mistake-col.wrong h3 { color: var(--bad); }
.mistake-col.right h3 { color: var(--good); }
.mistake-col pre { margin: 0; }
.mistake-col.wrong pre { background: var(--bad-tint); }
.mistake-col.right pre { background: var(--good-tint); }
.mistake-why { font-size: 0.94rem; color: var(--ink-2); }

/* --- code, static ---------------------------------------------- */

pre {
  font-size: 0.86rem;
  line-height: 1.6;
  background: var(--tint);
  border-radius: var(--radius);
  padding: 0.85rem 1rem;
  overflow-x: auto;
  margin: 0;
  color: var(--ink);
}
:not(pre) > code {
  font-size: 0.88em;
  background: var(--tint);
  padding: 0.12em 0.32em;
  border-radius: 3px;
}

/* --- runner (editor + output) ---------------------------------- */

.runner {
  margin: 1.25rem 0;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background: var(--bg-raised);
  overflow: hidden;
}

.runner-bar {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.4rem;
  padding: 0.45rem 0.5rem 0.45rem 0.85rem;
  border-bottom: 1px solid var(--rule);
  background: var(--tint);
}
.runner-name {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  color: var(--ink-3);
  margin-right: auto;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.runner-bar .btn { padding: 0.4rem 0.6rem; font-size: 0.8rem; }

.runner-editor { position: relative; }

.runner-editor textarea {
  display: block;
  width: 100%;
  border: 0;
  padding: 0.85rem 1rem;
  font-family: var(--mono);
  font-size: 0.86rem;
  line-height: 1.6;
  color: var(--ink);
  background: var(--bg-raised);
  resize: vertical;
  min-height: 6rem;
}
.runner-editor textarea:focus { outline: 2px solid var(--accent); outline-offset: -2px; }

.runner-out {
  border-top: 1px solid var(--rule);
  padding: 0.75rem 1rem;
  font-family: var(--mono);
  font-size: 0.83rem;
  line-height: 1.55;
  white-space: pre-wrap;
  word-break: break-word;
  background: var(--tint);
  color: var(--ink);
  max-height: 22rem;
  overflow-y: auto;
}
.runner-out:empty { display: none; }
.runner-out .out-status { color: var(--ink-3); font-style: italic; }
.runner-out .out-err { color: var(--bad); }
.runner-out .out-hint {
  color: var(--ink-2);
  border-left: 2px solid var(--bad);
  padding-left: 0.6rem;
  margin-top: 0.35rem;
  display: block;
  font-family: var(--sans);
  font-style: normal;
}
.runner-out .out-echo { color: var(--accent); }

.stdin-row {
  display: flex;
  gap: 0.4rem;
  align-items: center;
  margin: 0.35rem 0;
  flex-wrap: wrap;
}
.stdin-row input {
  font: inherit;
  font-family: var(--mono);
  flex: 1 1 8rem;
  min-width: 6rem;
  padding: 0.3rem 0.5rem;
  border: 1px solid var(--accent);
  border-radius: 3px;
  background: var(--bg-raised);
  color: var(--ink);
}
.stdin-row .btn { padding: 0.32rem 0.6rem; font-size: 0.78rem; }

.spinner {
  display: inline-block;
  width: 11px; height: 11px;
  border: 1.5px solid var(--rule-strong);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
  vertical-align: -1px;
  margin-right: 0.4rem;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* --- CodeMirror 5 theming (written here, not loaded from a CDN) - */

/* scoped under .runner so these beat CodeMirror's own sheet, which is
   injected into the head after this file */
.runner .CodeMirror {
  height: auto;
  font-family: var(--mono);
  font-size: 0.86rem;
  line-height: 1.6;
  background: var(--bg-raised);
  color: var(--ink);
}
.runner .CodeMirror-lines { padding: 0.7rem 0; }
.runner .CodeMirror pre.CodeMirror-line,
.runner .CodeMirror pre.CodeMirror-line-like { padding: 0 0.75rem; }
.runner .CodeMirror-gutters {
  background: var(--bg-raised);
  border-right: 1px solid var(--rule);
}
.runner .CodeMirror-linenumber { color: var(--ink-3); opacity: 0.7; font-size: 0.78rem; }
.runner .CodeMirror-cursor { border-left: 1.5px solid var(--ink); }
.runner .CodeMirror-selected,
.runner .CodeMirror-focused .CodeMirror-selected { background: var(--accent-tint); }
.runner .CodeMirror-focused { outline: 2px solid var(--accent); outline-offset: -2px; }
.runner .CodeMirror-activeline-background { background: var(--tint); }
.runner .cm-s-ppc .cm-keyword    { color: var(--accent); font-weight: 500; }
.runner .cm-s-ppc .cm-builtin    { color: var(--ink); font-weight: 500; }
.runner .cm-s-ppc .cm-string     { color: var(--bad); }
.runner .cm-s-ppc .cm-number     { color: var(--good); }
.runner .cm-s-ppc .cm-comment    { color: var(--ink-3); font-style: italic; }
.runner .cm-s-ppc .cm-operator   { color: var(--ink-2); }
.runner .cm-s-ppc .cm-variable,
.runner .cm-s-ppc .cm-variable-2,
.runner .cm-s-ppc .cm-def        { color: var(--ink); }
.runner .cm-s-ppc .cm-punctuation { color: var(--ink-2); }

/* --- practice --------------------------------------------------- */

.lesson-body > section { margin-bottom: 3.25rem; }
.lesson-body > section:last-child { margin-bottom: 0; }

.block-head {
  max-width: var(--measure);
  margin: 0 0 1.75rem;
  padding-top: 1rem;
  border-top: 1px solid var(--rule);
}
.block-head h2 { font-size: 1.6rem; margin-bottom: 0.4rem; }
.block-head p { color: var(--ink-2); margin: 0; font-size: 0.97rem; }

.task {
  max-width: var(--measure);
  margin-bottom: 2.5rem;
  padding-bottom: 2.5rem;
  border-bottom: 1px solid var(--rule);
}
.task:last-of-type { border-bottom: 0; }

.task-head {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
}
.task-num {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--ink-3);
  flex: none;
  padding-top: 0.1rem;
}
.task-prompt {
  font-family: var(--display);
  font-size: 1.12rem;
  font-weight: 600;
  letter-spacing: -0.012em;
  margin: 0;
}
.task-done-mark {
  color: var(--good);
  display: none;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.78rem;
  font-family: var(--mono);
  margin-left: auto;
  flex: none;
}
.task.is-done .task-done-mark { display: inline-flex; }
.task.is-done .task-num { color: var(--good); }

.task-feedback {
  margin-top: 0.75rem;
  font-size: 0.94rem;
  padding: 0.7rem 0.9rem;
  border-radius: var(--radius);
  border-left: 2px solid var(--rule-strong);
  background: var(--tint);
  color: var(--ink-2);
}
.task-feedback.is-pass { border-left-color: var(--good); background: var(--good-tint); color: var(--ink); }
.task-feedback.is-nudge { border-left-color: var(--accent); background: var(--accent-tint); color: var(--ink); }

.task-extras {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-top: 0.75rem;
  margin-left: -0.5rem;   /* line the quiet button up with the editor edge */
}

details.reveal { margin-top: 0.75rem; }
details.reveal > summary {
  font-size: 0.875rem;
  color: var(--accent);
  cursor: pointer;
  list-style: none;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.2rem 0;
}
details.reveal > summary::-webkit-details-marker { display: none; }
details.reveal > summary:hover { color: var(--accent-hover); }
details.reveal[open] > summary { margin-bottom: 0.5rem; }
details.reveal pre { font-size: 0.83rem; }
.reveal-locked {
  font-size: 0.875rem;
  color: var(--ink-3);
  margin-top: 0.75rem;
}

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

.quiz-item {
  max-width: var(--measure);
  margin-bottom: 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--rule);
}
.quiz-item:last-of-type { border-bottom: 0; }

.quiz-q {
  font-family: var(--display);
  font-size: 1.08rem;
  font-weight: 600;
  letter-spacing: -0.012em;
  margin: 0 0 0.9rem;
  display: flex;
  gap: 0.75rem;
}
.quiz-q .task-num { font-family: var(--mono); }

.quiz-options { display: grid; gap: 0.5rem; }

.quiz-opt {
  font: inherit;
  font-size: 0.95rem;
  text-align: left;
  color: var(--ink);
  background: var(--bg-raised);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: 0.65rem 0.85rem;
  cursor: pointer;
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  transition: border-color 0.14s ease, background 0.14s ease;
}
.quiz-opt:hover { border-color: var(--ink-3); }
.quiz-opt .mark { flex: none; width: 16px; height: 16px; margin-top: 0.18rem; opacity: 0; }
.quiz-opt.is-right { border-color: var(--good); background: var(--good-tint); }
.quiz-opt.is-right .mark { opacity: 1; color: var(--good); }
.quiz-opt.is-wrong { border-color: var(--bad); background: var(--bad-tint); }
.quiz-opt.is-wrong .mark { opacity: 1; color: var(--bad); }
.quiz-answered .quiz-opt { cursor: default; }

.quiz-explain {
  margin-top: 0.75rem;
  font-size: 0.94rem;
  color: var(--ink-2);
  border-left: 2px solid var(--rule-strong);
  padding-left: 0.75rem;
}
.quiz-actions { margin-top: 0.5rem; margin-left: -0.5rem; }
.quiz-actions:empty { display: none; }

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

.quiz-head {
  padding: clamp(2.25rem, 6vw, 3.5rem) 0 1.5rem;
  max-width: var(--measure);
}
.quiz-head h1 { font-size: clamp(1.9rem, 5.5vw, 2.7rem); }
.quiz-head .lede { margin: 0.75rem 0 0; color: var(--ink-2); }

#quiz-body { padding-bottom: 4rem; }

.quiz-counter {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-3);
  max-width: var(--measure);
  margin: 0 0 1.5rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid var(--rule);
}

/* the question's code sample */
.quiz-item > pre { margin: 0 0 0.9rem; }

/* predicted-output options are code, so set them as code */
.quiz-options.is-code .opt-code {
  font-family: var(--mono);
  font-size: 0.85rem;
  white-space: pre-wrap;
  line-height: 1.5;
}

/* typed answers */
.quiz-write {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  align-items: stretch;
}
.quiz-write-field {
  font: inherit;
  font-family: var(--mono);
  font-size: 0.88rem;
  flex: 1 1 14rem;
  min-width: 0;
  padding: 0.55rem 0.7rem;
  color: var(--ink);
  background: var(--bg-raised);
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius);
}
.quiz-write-field::placeholder { color: var(--ink-3); font-family: var(--sans); font-size: 0.85rem; }
.quiz-write-field:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
.quiz-write.is-right .quiz-write-field { border-color: var(--good); background: var(--good-tint); }
.quiz-write.is-wrong .quiz-write-field { border-color: var(--bad); background: var(--bad-tint); }

/* what to go back and read */
.quiz-summary {
  max-width: var(--measure);
  margin-top: 2.5rem;
  padding: 1.25rem 1.4rem;
  border: 1px solid var(--rule);
  border-left: 2px solid var(--accent);
  border-radius: 0 var(--radius) var(--radius) 0;
}
.quiz-summary h2 { font-size: 1.2rem; margin-bottom: 0.5rem; }
.quiz-summary p { color: var(--ink-2); margin-bottom: 0.75rem; }
.quiz-review { margin: 0; padding-left: 1.1rem; }
.quiz-review li { margin-bottom: 0.3rem; }
.quiz-review li::marker { color: var(--ink-3); }

.quiz-back { max-width: var(--measure); margin-top: 2rem; font-size: 0.94rem; }

.tag-done { color: var(--accent); border-color: var(--accent); }

/* --- cheatsheet + next ------------------------------------------ */

.cheatsheet {
  max-width: var(--measure);
  margin: 0;
  display: grid;
  gap: 0;
}
.cheat-row {
  display: grid;
  grid-template-columns: minmax(9rem, 15rem) 1fr;
  gap: 0.5rem 1.25rem;
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--rule);
  align-items: baseline;
}
.cheat-row:first-child { border-top: 1px solid var(--rule); }
.cheat-row dt { font-family: var(--mono); font-size: 0.84rem; }
.cheat-row dd { margin: 0; color: var(--ink-2); font-size: 0.94rem; }
@media (max-width: 30rem) {
  .cheat-row { grid-template-columns: 1fr; gap: 0.15rem; }
}

.next-up {
  max-width: var(--measure);
  margin-top: 1rem;
  padding: 1.1rem 1.25rem;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
}
.next-up h2 {
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin-bottom: 0.4rem;
}
.next-up p { margin: 0; color: var(--ink-2); }
.next-up-go { margin-top: 0.9rem !important; }
.next-up-soon {
  margin-top: 0.7rem !important;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
  color: var(--ink-3) !important;
  font-size: 0.9rem;
}

/* --- previous / next along the bottom ------------------------------ */

.lesson-nav {
  max-width: var(--measure);
  margin: 2.5rem 0 3rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}
.lesson-nav-link {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  padding: 0.85rem 1rem;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  text-decoration: none;
  color: inherit;
  background: var(--bg-raised);
}
a.lesson-nav-link:hover { border-color: var(--rule-strong); }
.lesson-nav-link.is-next { text-align: right; }
.lesson-nav-link.is-locked { opacity: 0.55; background: none; }
.lesson-nav-label {
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-3);
}
.lesson-nav-title { font-size: 0.94rem; }
@media (max-width: 30rem) {
  .lesson-nav { grid-template-columns: 1fr; }
  .lesson-nav-link.is-next { text-align: left; }
}

/* --- playground -------------------------------------------------- */

.pg-head {
  padding: 2rem 0 1.25rem;
  display: flex;
  align-items: flex-end;
  gap: 1rem;
  flex-wrap: wrap;
}
.pg-head h1 { font-size: 1.6rem; margin-right: auto; }
.pg-head label {
  font-size: 0.8rem;
  color: var(--ink-3);
  display: flex;
  align-items: center;
  gap: 0.45rem;
}
.pg-head select {
  font: inherit;
  font-size: 0.85rem;
  color: var(--ink);
  background: var(--bg-raised);
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius);
  padding: 0.4rem 0.5rem;
  max-width: 15rem;
}
.pg-runner { margin-bottom: 3rem; }
.pg-runner .CodeMirror { min-height: 14rem; }
.pg-runner .runner-editor textarea { min-height: 14rem; }
.pg-runner .runner-out { min-height: 7rem; }
.pg-runner .runner-out:empty { display: block; }
.pg-runner .runner-out:empty::before {
  content: "Output appears here when you press Run.";
  color: var(--ink-3);
  font-family: var(--sans);
  font-style: italic;
}

/* --- 404 --------------------------------------------------------- */

.notfound {
  max-width: var(--measure);
  padding: clamp(4rem, 15vh, 8rem) 0 6rem;
}
.notfound .lesson-eyebrow { margin-bottom: 1rem; }
.notfound h1 { font-size: clamp(1.9rem, 5vw, 2.5rem); margin-bottom: 0.75rem; }
.notfound p { color: var(--ink-2); }

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

.site-footer {
  border-top: 1px solid var(--rule);
  margin-top: auto;
  padding: 1.75rem 0 2.5rem;
  font-size: 0.83rem;
  color: var(--ink-3);
}
.site-footer .wrap {
  display: flex;
  gap: 1rem;
  align-items: center;
  flex-wrap: wrap;
}
.site-footer p { margin: 0; margin-right: auto; }
.site-footer .btn-quiet { font-size: 0.83rem; color: var(--ink-3); }
.site-footer .btn-quiet:hover { color: var(--ink); }
@media (max-width: 40rem) {
  .site-footer .btn-quiet { margin-left: -0.5rem; }
}

body { display: flex; flex-direction: column; min-height: 100vh; }
main { flex: 1 0 auto; }