/* ============================================================
   style.css — Computing for Mathematics
   Adapted from vknight.org; teal-forward palette.
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600&family=JetBrains+Mono:wght@400;500&display=swap');

/* ---- Custom properties (Catppuccin Mocha — dark) --------------- */
:root {
  --bg:           #1e1e2e;
  --surface:      #313244;
  --surface-2:    #45475a;
  --border:       #585b70;
  --text:         #cdd6f4;
  --text-muted:   #a6adc8;
  --accent:       #89dceb;   /* sky/teal (primary) */
  --accent-dim:   rgba(137, 220, 235, 0.14);
  --accent-warm:  #fab387;   /* peach  */
  --green:        #a6e3a1;   /* green  */
  --teal:         #89dceb;   /* sky    */
  --mauve:        #cba6f7;   /* mauve  */
  --red:          #f38ba8;   /* red    */
  --yellow:       #f9e2af;   /* yellow */
  --radius:       6px;
  --nav-h:        54px;
  --max-w:        780px;
  --font:         'Inter', system-ui, -apple-system, sans-serif;
  --mono:         'JetBrains Mono', 'Fira Code', ui-monospace, monospace;
  --transition:   0.15s ease;
}

/* ---- Custom properties (Catppuccin Latte — light) -------------- */
[data-theme="light"] {
  --bg:           #eff1f5;
  --surface:      #e6e9ef;
  --surface-2:    #dce0e8;
  --border:       #ccd0da;
  --text:         #4c4f69;
  --text-muted:   #8c8fa1;
  --accent:       #04a5e5;   /* sky (primary) */
  --accent-dim:   rgba(4, 165, 229, 0.10);
  --accent-warm:  #fe640b;   /* peach  */
  --green:        #40a02b;   /* green  */
  --teal:         #04a5e5;   /* sky    */
  --mauve:        #8839ef;   /* mauve  */
  --red:          #d20f39;   /* red    */
  --yellow:       #df8e1d;   /* yellow */
}

/* ---- Reset ----------------------------------------------------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
  border-radius: var(--radius);
}

/* ---- Base ------------------------------------------------------ */
html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  background: var(--bg);
  background-image:
    radial-gradient(ellipse at 80% 0%, rgba(137, 220, 235, 0.07) 0%, transparent 60%),
    radial-gradient(ellipse at 0% 80%, rgba(166, 227, 161, 0.05) 0%, transparent 50%);
  color: var(--text);
  font-family: var(--font);
  font-size: 1rem;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

[data-theme="light"] body,
[data-theme="light"] {
  background-image:
    radial-gradient(ellipse at 80% 0%, rgba(4, 165, 229, 0.05) 0%, transparent 60%),
    radial-gradient(ellipse at 0% 80%, rgba(64, 160, 43, 0.04) 0%, transparent 50%);
}

/* ---- Layout ---------------------------------------------------- */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 2.5rem 1.25rem 5rem;
  flex: 1;
}

/* ---- Nav ------------------------------------------------------- */
header {
  height: var(--nav-h);
  background: color-mix(in srgb, var(--surface) 85%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 2px solid transparent;
  border-image: linear-gradient(90deg, var(--teal), var(--green), var(--yellow)) 1;
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.5rem;
  gap: 1rem;
}

.logo {
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: -0.02em;
  text-decoration: none;
  background: linear-gradient(90deg, var(--teal), var(--green));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  transition: opacity var(--transition);
}

.logo:hover {
  opacity: 0.8;
  text-decoration: none;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 1.5rem;
}

nav a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  transition: color var(--transition);
}

nav a:hover {
  color: var(--text);
  text-decoration: none;
}

/* ---- Theme toggle button --------------------------------------- */
#theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-muted);
  cursor: pointer;
  font-size: 1rem;
  line-height: 1;
  padding: 0.3rem 0.5rem;
  transition: color var(--transition), border-color var(--transition);
}

#theme-toggle:hover {
  color: var(--text);
  border-color: var(--text-muted);
}

/* ---- Typography ------------------------------------------------ */
h1, h2, h3, h4, h5 {
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.025em;
  color: var(--text);
}

h1 {
  background: linear-gradient(90deg, var(--teal), var(--green));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

h2 {
  color: var(--teal);
}

h3 { color: var(--green); }

h1 { font-size: 1.875rem; margin: 2rem 0 1rem; }
h2 { font-size: 1.375rem; margin: 2.5rem 0 0.75rem; }
h3 { font-size: 1.125rem; margin: 2rem 0 0.5rem; }
h4, h5 { font-size: 1rem;   margin: 1.5rem 0 0.5rem; }

p {
  margin-bottom: 1.25rem;
  color: var(--text);
}

small {
  color: var(--text-muted);
  font-size: 0.8125rem;
}

strong { font-weight: 600; }

em { font-style: italic; }

hr {
  border: none;
  height: 2px;
  background: linear-gradient(90deg, var(--teal), var(--green), var(--yellow));
  opacity: 0.5;
  margin: 2.5rem 0;
  border-radius: 999px;
}

/* ---- Links ----------------------------------------------------- */
a {
  color: var(--accent);
  text-decoration: none;
  transition: opacity var(--transition);
}

a:hover {
  opacity: 0.75;
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---- Lists ----------------------------------------------------- */
ul, ol {
  padding-left: 1.4rem;
  margin-bottom: 1.5rem;
}

li {
  margin-bottom: 0.5rem;
  color: var(--text);
}

/* ---- Code ------------------------------------------------------ */
code {
  font-family: var(--mono);
  font-size: 0.8125em;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.125em 0.375em;
  color: var(--accent-warm);
}

pre {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  padding: 1.25rem;
  overflow-x: auto;
  margin-bottom: 1.5rem;
  font-size: 0.875rem;
  line-height: 1.6;
}

pre code {
  background: none;
  border: none;
  padding: 0;
  color: var(--text);
  font-size: inherit;
}

/* ---- Blockquote ------------------------------------------------ */
blockquote {
  border-left: 3px solid var(--teal);
  padding: 0.25rem 0 0.25rem 1.25rem;
  margin: 1.5rem 0;
  color: var(--text-muted);
  font-style: italic;
}

/* ---- Tables ---------------------------------------------------- */
table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 1.5rem;
  font-size: 0.9375rem;
}

th {
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.5rem 0.75rem;
  border-bottom: 1px solid var(--border);
  text-align: left;
}

td {
  padding: 0.6rem 0.75rem;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

tr:last-child td {
  border-bottom: none;
}

/* ---- Post list ------------------------------------------------- */
.post-list {
  list-style: none;
  padding-left: 0;
}

.post-list > li {
  padding-bottom: 1rem;
  margin-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}

.post-list > li:last-child {
  border-bottom: none;
}

.post-list small {
  display: inline-block;
  margin-right: 0.5rem;
  font-variant-numeric: tabular-nums;
}

/* ---- Facilitator-only banner ---------------------------------- */
.facilitator-banner {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 4px solid var(--yellow);
  border-radius: var(--radius);
  padding: 0.75rem 1rem;
  margin-bottom: 2rem;
  font-size: 0.875rem;
  color: var(--text-muted);
}

.facilitator-banner strong { color: var(--yellow); }

/* Wrap the whole facilitator page so it reads as something distinct. */
.facilitator-notes {
  border: 3px solid var(--text);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin-top: 1rem;
}

/* ---- Footer ---------------------------------------------------- */
footer {
  text-align: center;
  padding: 1.5rem 1rem 2rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
  margin-top: 2rem;
}

footer a {
  color: var(--text-muted);
}

/* ---- Responsive ----------------------------------------------- */
@media (max-width: 600px) {
  :root { --max-w: 100%; }

  .container { padding: 1.5rem 1rem 3rem; }

  h1 { font-size: 1.5rem; }
  h2 { font-size: 1.25rem; }

  header { padding: 0 1rem; }

  nav ul { gap: 0.875rem; }
  nav a { font-size: 0.8125rem; }
}

/* ---- Revision quizzes ----------------------------------------- */
.quiz-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin: 1rem 0 2rem;
}

.quiz-progress {
  font-size: 0.8125rem;
  color: var(--text-muted);
  margin: 0 0 0.5rem;
}

.quiz-question {
  font-weight: 600;
  margin: 0 0 1rem;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.quiz-option {
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  padding: 0.6rem 0.8rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: border-color var(--transition), background var(--transition);
}

.quiz-option:hover {
  border-color: var(--accent);
}

.quiz-option input {
  accent-color: var(--accent);
}

.quiz-option.quiz-correct {
  border-color: var(--green);
  background: color-mix(in srgb, var(--green) 14%, transparent);
}

.quiz-option.quiz-incorrect {
  border-color: var(--red);
  background: color-mix(in srgb, var(--red) 14%, transparent);
}

.quiz-explain {
  font-size: 0.9375rem;
  color: var(--text-muted);
  border-left: 3px solid var(--border);
  padding-left: 0.75rem;
  margin: 0 0 1rem;
}

.quiz-btn {
  font: inherit;
  font-weight: 600;
  color: var(--bg);
  background: var(--accent);
  border: none;
  border-radius: var(--radius);
  padding: 0.5rem 1.1rem;
  cursor: pointer;
}

.quiz-btn:disabled {
  opacity: 0.5;
  cursor: default;
}

.quiz-score {
  font-weight: 600;
  margin: 0 0 1rem;
}

/* ---- Framed inset figure (e.g. the personas diagram) ---------- */
.persona-figure {
  margin: 1.5rem 0;
  padding: 0.75rem;
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-align: center;
}

.persona-figure img {
  max-width: 100%;
  height: auto;
  display: block;
  margin: 0 auto;
}