/* ============================================================
   SCS2303 Software Architecture — Interactive Concepts Website
   Shared stylesheet. Light + dark theme via CSS variables.
   ============================================================ */

:root {
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SF Mono", ui-monospace, "Cascadia Code", "JetBrains Mono", Menlo, Consolas, monospace;

  /* Light theme (default) */
  --bg: #f6f7f9;
  --bg-panel: #ffffff;
  --bg-inset: #eef0f4;
  --text: #1c2330;
  --text-soft: #52607a;
  --border: #dde2ea;
  --shadow: 0 1px 3px rgba(16, 24, 40, .07), 0 8px 24px -12px rgba(16, 24, 40, .12);

  --accent: #3f6fde;        /* primary blue */
  --accent-soft: #e8eefc;
  --green: #1f9d6b;
  --green-soft: #e3f5ec;
  --red: #d5484f;
  --red-soft: #fdeaea;
  --amber: #b97a0a;
  --amber-soft: #fdf3df;
  --purple: #7b5bd6;
  --purple-soft: #f0ebfc;
  --teal: #0e8f97;
  --teal-soft: #e0f4f5;

  /* Code block (always dark for contrast) */
  --code-bg: #171d2b;
  --code-text: #dbe2f0;
  --code-border: #2a3348;
  --tok-k: #c792ea;   /* keyword */
  --tok-t: #82aaff;   /* type */
  --tok-s: #c3e88d;   /* string */
  --tok-c: #697798;   /* comment */
  --tok-n: #f78c6c;   /* number */
  --tok-m: #ffcb6b;   /* method call */

  --sidebar-w: 272px;
  --radius: 12px;
}

html[data-theme="dark"] {
  --bg: #0f1420;
  --bg-panel: #171d2b;
  --bg-inset: #1f2637;
  --text: #e4e9f4;
  --text-soft: #93a0ba;
  --border: #2a3348;
  --shadow: 0 1px 3px rgba(0, 0, 0, .4), 0 8px 24px -12px rgba(0, 0, 0, .5);

  --accent: #7aa2ff;
  --accent-soft: #1d2942;
  --green: #4cc490;
  --green-soft: #12291f;
  --red: #f07a80;
  --red-soft: #331a1c;
  --amber: #e0a72e;
  --amber-soft: #2e2410;
  --purple: #a68cf0;
  --purple-soft: #241d3a;
  --teal: #45c2ca;
  --teal-soft: #0e2a2c;

  --code-bg: #10151f;
  --code-border: #232c40;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  font-size: 16px;
}

/* ---------- Layout ---------- */
#layout { display: flex; min-height: 100vh; }

#sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  background: var(--bg-panel);
  border-right: 1px solid var(--border);
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  padding: 18px 14px 40px;
}

#content {
  flex: 1;
  min-width: 0;
  padding: 36px clamp(20px, 5vw, 64px) 120px;
  max-width: 980px;
  margin: 0 auto;
}

/* Sidebar */
.side-title {
  font-weight: 800;
  font-size: 15px;
  letter-spacing: .02em;
  padding: 6px 10px 2px;
}
.side-title a { color: var(--text); text-decoration: none; }
.side-sub { font-size: 12px; color: var(--text-soft); padding: 0 10px 12px; }

.side-group { font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: .08em; color: var(--text-soft); margin: 18px 10px 6px; }

.side-link {
  display: block;
  padding: 6px 10px;
  border-radius: 8px;
  color: var(--text-soft);
  text-decoration: none;
  font-size: 13.5px;
  line-height: 1.4;
}
.side-link:hover { background: var(--bg-inset); color: var(--text); }
.side-link.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }

.side-toc { margin: 2px 0 4px 14px; border-left: 1px solid var(--border); }
.side-toc a {
  display: block; padding: 3px 10px; font-size: 12.5px;
  color: var(--text-soft); text-decoration: none; border-radius: 0 8px 8px 0;
}
.side-toc a:hover { color: var(--accent); background: var(--bg-inset); }

#theme-toggle {
  margin: 6px 10px 0; padding: 5px 12px; font-size: 12.5px;
  border: 1px solid var(--border); border-radius: 999px;
  background: var(--bg-inset); color: var(--text-soft); cursor: pointer;
}
#theme-toggle:hover { color: var(--text); }

/* Mobile */
#menu-btn { display: none; }
@media (max-width: 900px) {
  #layout { display: block; }
  #sidebar {
    position: fixed; z-index: 50; left: 0; top: 0; transform: translateX(-100%);
    visibility: hidden; /* keep the closed drawer out of the keyboard tab order */
    transition: transform .25s ease, visibility .25s;
    box-shadow: var(--shadow); height: 100vh;
  }
  #sidebar.open { transform: translateX(0); visibility: visible; }
  #menu-btn {
    display: block; position: fixed; z-index: 60; top: 14px; left: 14px;
    padding: 8px 12px; border-radius: 10px; border: 1px solid var(--border);
    background: var(--bg-panel); color: var(--text); cursor: pointer; font-size: 15px;
    box-shadow: var(--shadow);
  }
  #content { padding-top: 64px; }
}

/* ---------- Typography ---------- */
h1 { font-size: clamp(28px, 4vw, 38px); line-height: 1.2; letter-spacing: -0.02em; margin: 0 0 10px; font-weight: 800; }
h2 {
  font-size: 25px; margin: 56px 0 14px; font-weight: 750; letter-spacing: -0.01em;
  padding-top: 14px; border-top: 1px solid var(--border);
}
h3 { font-size: 19px; margin: 34px 0 10px; font-weight: 700; }
h4 { font-size: 16px; margin: 24px 0 8px; font-weight: 700; }
p { margin: 0 0 14px; }
li { margin: 4px 0; }
a { color: var(--accent); }
strong { font-weight: 650; }
hr { border: none; border-top: 1px solid var(--border); margin: 40px 0; }

.lede { font-size: 18px; color: var(--text-soft); margin-bottom: 26px; }

.kicker {
  display: inline-block; font-size: 12px; font-weight: 700; letter-spacing: .1em;
  text-transform: uppercase; color: var(--accent); margin-bottom: 8px;
}

/* Anchor offset so sticky content doesn't hide headings */
h2[id], h3[id] { scroll-margin-top: 24px; }

/* ---------- Cards & callouts ---------- */
.card {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  margin: 18px 0;
}

.grid { display: grid; gap: 14px; margin: 18px 0; }
.grid.cols-2 { grid-template-columns: repeat(auto-fit, minmax(min(280px, 100%), 1fr)); }
.grid.cols-3 { grid-template-columns: repeat(auto-fit, minmax(min(220px, 100%), 1fr)); }
.grid > .card { margin: 0; }

.callout {
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  background: var(--bg-panel);
  border-radius: 10px;
  padding: 14px 18px;
  margin: 18px 0;
}
.callout .co-title { font-weight: 700; font-size: 13.5px; letter-spacing: .02em; margin-bottom: 4px; display: flex; align-items: center; gap: 7px; }
.callout p:last-child { margin-bottom: 0; }

.callout.why      { border-left-color: var(--purple); }
.callout.why      .co-title { color: var(--purple); }
.callout.analogy  { border-left-color: var(--teal); }
.callout.analogy  .co-title { color: var(--teal); }
.callout.warn     { border-left-color: var(--red); }
.callout.warn     .co-title { color: var(--red); }
.callout.confuse  { border-left-color: var(--amber); }
.callout.confuse  .co-title { color: var(--amber); }
.callout.tip      { border-left-color: var(--green); }
.callout.tip      .co-title { color: var(--green); }
.callout.info     { border-left-color: var(--accent); }
.callout.info     .co-title { color: var(--accent); }

/* Good / bad code panels */
.good-bad { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(300px, 100%), 1fr)); gap: 14px; margin: 18px 0; }
.panel-bad, .panel-good { border-radius: var(--radius); border: 1px solid var(--border); overflow: hidden; background: var(--bg-panel); }
.panel-bad  > .panel-label { background: var(--red-soft); color: var(--red); }
.panel-good > .panel-label { background: var(--green-soft); color: var(--green); }
.panel-label { font-size: 12.5px; font-weight: 700; padding: 7px 14px; letter-spacing: .03em; }
.panel-bad pre, .panel-good pre { margin: 0; border: none; border-radius: 0; }
.panel-bad .panel-note, .panel-good .panel-note { padding: 10px 14px; font-size: 13.5px; color: var(--text-soft); }

/* Pills / badges */
.pill {
  display: inline-block; font-size: 11.5px; font-weight: 700; padding: 2px 10px;
  border-radius: 999px; letter-spacing: .03em; vertical-align: middle;
}
.pill.creational { background: var(--green-soft); color: var(--green); }
.pill.structural { background: var(--accent-soft); color: var(--accent); }
.pill.behavioral { background: var(--purple-soft); color: var(--purple); }
.pill.arch       { background: var(--teal-soft); color: var(--teal); }
.pill.neutral    { background: var(--bg-inset); color: var(--text-soft); }

/* ---------- Code ---------- */
pre {
  background: var(--code-bg);
  color: var(--code-text);
  border: 1px solid var(--code-border);
  border-radius: var(--radius);
  padding: 16px 18px;
  overflow-x: auto;
  font-size: 13.5px;
  line-height: 1.6;
  margin: 16px 0;
  position: relative;
}
pre code { font-family: var(--font-mono); background: none; padding: 0; font-size: inherit; color: inherit; }

:not(pre) > code {
  font-family: var(--font-mono);
  font-size: .88em;
  background: var(--bg-inset);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1px 6px;
  overflow-wrap: anywhere; /* long identifiers must wrap, not overflow, on phones */
}

.tok-k { color: var(--tok-k); }
.tok-t { color: var(--tok-t); }
.tok-s { color: var(--tok-s); }
.tok-c { color: var(--tok-c); font-style: italic; }
.tok-n { color: var(--tok-n); }
.tok-m { color: var(--tok-m); }

.code-copy {
  position: absolute; top: 8px; right: 8px;
  font-size: 11px; padding: 3px 9px; border-radius: 7px;
  border: 1px solid var(--code-border); background: rgba(23,29,43,.85);
  color: #9aa7c4; cursor: pointer; opacity: 0; transition: opacity .15s;
}
pre:hover .code-copy, .code-copy:focus-visible { opacity: 1; }
@media (hover: none) { .code-copy { opacity: .75; } } /* touch devices: always visible */
.code-copy:hover { color: #fff; }

/* Runnable-vs-fragment badge: <pre data-code="runnable"> / <pre data-code="fragment"> */
pre[data-code]::before {
  content: "✂ fragment — illustrates the idea; needs a surrounding program";
  position: sticky; left: 0; display: block;
  font-family: var(--font-body); font-size: 10.5px; letter-spacing: .04em;
  color: #8b98b8; margin: -6px 0 8px;
}
pre[data-code="runnable"]::before {
  content: "▶ runnable — paste into a console app as-is";
  color: var(--tok-s);
}
pre[data-code="complete"]::before {
  content: "✔ compiles — all types are complete; add a Main/usage line to run it";
  color: var(--tok-t);
}

.code-title {
  font-family: var(--font-mono); font-size: 12px; color: var(--text-soft);
  margin: 16px 0 -12px; padding-left: 4px;
}

/* ---------- Tables ---------- */
.table-wrap { overflow-x: auto; margin: 18px 0; border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg-panel); }
table { border-collapse: collapse; width: 100%; font-size: 14px; }
th, td { text-align: left; padding: 10px 14px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { background: var(--bg-inset); font-size: 12.5px; letter-spacing: .04em; text-transform: uppercase; color: var(--text-soft); }
tr:last-child td { border-bottom: none; }

/* ---------- Tabs ---------- */
.tabs { margin: 18px 0; border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg-panel); overflow: hidden; }
.tab-bar { display: flex; flex-wrap: wrap; border-bottom: 1px solid var(--border); background: var(--bg-inset); }
.tab-bar button {
  padding: 9px 18px; border: none; background: none; cursor: pointer;
  font-size: 13.5px; font-weight: 600; color: var(--text-soft);
  border-bottom: 2px solid transparent; margin-bottom: -1px; font-family: inherit;
}
.tab-bar button.active { color: var(--accent); border-bottom-color: var(--accent); background: var(--bg-panel); }
.tab-panel { display: none; padding: 6px 18px 14px; }
.tab-panel.active { display: block; }
.tab-panel > pre:first-child { margin-top: 12px; }

/* ---------- Collapsible ---------- */
details {
  border: 1px solid var(--border); border-radius: var(--radius);
  background: var(--bg-panel); margin: 14px 0; padding: 0 18px;
}
details summary {
  cursor: pointer; font-weight: 650; padding: 12px 0; font-size: 14.5px;
  list-style: none; display: flex; align-items: center; gap: 8px;
}
details summary::before { content: "▸"; color: var(--accent); transition: transform .15s; font-size: 12px; }
details[open] summary::before { transform: rotate(90deg); }
details[open] summary { border-bottom: 1px dashed var(--border); margin-bottom: 10px; }
details > *:last-child { margin-bottom: 14px; }

/* ---------- Interactive demo panels ---------- */
.demo {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-panel);
  margin: 22px 0;
  overflow: hidden;
  box-shadow: var(--shadow);
}
.demo-head {
  padding: 10px 18px; background: var(--bg-inset); border-bottom: 1px solid var(--border);
  font-weight: 700; font-size: 13.5px; display: flex; align-items: center; gap: 8px;
}
.demo-head::before { content: "⚡"; }
.demo-body { padding: 18px; }
.demo-note { font-size: 13px; color: var(--text-soft); margin-top: 10px; }

.btn {
  font-family: inherit; font-size: 13.5px; font-weight: 600;
  padding: 7px 16px; border-radius: 9px; cursor: pointer;
  border: 1px solid var(--border); background: var(--bg-inset); color: var(--text);
  transition: filter .1s;
}
.btn:hover { filter: brightness(.96); }
html[data-theme="dark"] .btn:hover { filter: brightness(1.15); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.danger  { background: var(--red-soft); border-color: transparent; color: var(--red); }
.btn.success { background: var(--green-soft); border-color: transparent; color: var(--green); }
.btn:disabled { opacity: .45; cursor: not-allowed; }
.btn-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 10px 0; align-items: center; }

select.demo-select, input.demo-input {
  font-family: inherit; font-size: 13.5px; padding: 7px 10px;
  border-radius: 9px; border: 1px solid var(--border);
  background: var(--bg-panel); color: var(--text);
  max-width: 100%;
}

.log {
  font-family: var(--font-mono); font-size: 12.5px; line-height: 1.7;
  background: var(--code-bg); color: var(--code-text);
  border: 1px solid var(--code-border);
  border-radius: 10px; padding: 12px 14px; margin-top: 12px;
  max-height: 260px; overflow-y: auto; white-space: pre-wrap;
}
.log:empty::before { content: "— output will appear here —"; color: var(--tok-c); }
.log .log-dim { color: var(--tok-c); }
.log .log-ok { color: var(--tok-s); }
.log .log-err { color: #f07a80; }
.log .log-hi { color: var(--tok-m); }

/* ---------- SVG diagrams ---------- */
.diagram {
  margin: 20px 0; padding: 18px; text-align: center;
  background: var(--bg-panel); border: 1px solid var(--border); border-radius: var(--radius);
  overflow-x: auto;
}
/* Diagrams keep their natural (readable) width; the .diagram wrapper pans
   horizontally on narrow screens instead of shrinking text to ~6px. */
.diagram svg { max-width: none; height: auto; }
.diagram .caption { font-size: 13px; color: var(--text-soft); margin-top: 10px; text-align: center; }

/* Standard SVG classes for UML-ish diagrams */
svg .box       { fill: var(--bg-inset); stroke: var(--text-soft); stroke-width: 1.3; rx: 6; }
svg .box-hi    { fill: var(--accent-soft); stroke: var(--accent); stroke-width: 1.5; rx: 6; }
svg .box-good  { fill: var(--green-soft); stroke: var(--green); stroke-width: 1.5; rx: 6; }
svg .box-bad   { fill: var(--red-soft); stroke: var(--red); stroke-width: 1.5; rx: 6; }
svg .box-warn  { fill: var(--amber-soft); stroke: var(--amber); stroke-width: 1.5; rx: 6; }
svg .box-purple{ fill: var(--purple-soft); stroke: var(--purple); stroke-width: 1.5; rx: 6; }
svg text       { fill: var(--text); font-family: var(--font-body); font-size: 13px; }
svg .t-small   { font-size: 11px; fill: var(--text-soft); }
svg .t-mono    { font-family: var(--font-mono); font-size: 11.5px; }
svg .t-bold    { font-weight: 700; }
svg .t-italic  { font-style: italic; }
svg .edge      { stroke: var(--text-soft); stroke-width: 1.3; fill: none; }
svg .edge-hi   { stroke: var(--accent); stroke-width: 1.6; fill: none; }
svg .edge-dash { stroke: var(--text-soft); stroke-width: 1.3; fill: none; stroke-dasharray: 5 4; }
svg .arrow-head { fill: var(--text-soft); }
svg .arrow-head-open { fill: var(--bg-panel); stroke: var(--text-soft); stroke-width: 1.3; }

/* ---------- Quiz ---------- */
.quiz { border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg-panel); margin: 22px 0; overflow: hidden; }
.quiz-head { padding: 10px 18px; background: var(--purple-soft); color: var(--purple); font-weight: 700; font-size: 13.5px; }
.quiz-q { padding: 16px 18px 4px; font-weight: 600; }
.quiz-opts { padding: 4px 18px 14px; display: grid; gap: 8px; }
.quiz-opt {
  text-align: left; font-family: inherit; font-size: 14px; padding: 10px 14px;
  border-radius: 10px; border: 1px solid var(--border); background: var(--bg-inset);
  color: var(--text); cursor: pointer; line-height: 1.5;
  min-width: 0; overflow-wrap: anywhere; /* inline code inside options must not force overflow */
}
.quiz-opt:hover:not(:disabled) { border-color: var(--accent); }
.quiz-opt.correct { background: var(--green-soft); border-color: var(--green); color: var(--green); font-weight: 600; }
.quiz-opt.wrong   { background: var(--red-soft); border-color: var(--red); color: var(--red); }
.quiz-opt:disabled { cursor: default; }
.quiz-expl { margin: 0 18px 16px; padding: 12px 14px; border-radius: 10px; background: var(--bg-inset); font-size: 13.5px; display: none; }
.quiz-expl.show { display: block; }
.quiz-progress { padding: 8px 18px 14px; font-size: 12.5px; color: var(--text-soft); }

/* ---------- Page footer nav ---------- */
.page-nav { display: flex; justify-content: space-between; gap: 14px; margin-top: 70px; }
.page-nav a {
  flex: 1; text-decoration: none; border: 1px solid var(--border); border-radius: var(--radius);
  padding: 14px 18px; background: var(--bg-panel); color: var(--text);
}
.page-nav a:hover { border-color: var(--accent); }
.page-nav .dir { font-size: 12px; color: var(--text-soft); display: block; }
.page-nav .next { text-align: right; }
.page-nav .title { font-weight: 650; color: var(--accent); }

/* ---------- Home page extras ---------- */
.hero {
  padding: 40px 0 8px;
}
.chapter-card {
  display: block; text-decoration: none; color: var(--text);
  background: var(--bg-panel); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 18px 20px; transition: border-color .15s, transform .15s;
}
.chapter-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.chapter-card .num { font-size: 12px; font-weight: 800; color: var(--accent); letter-spacing: .06em; }
.chapter-card h3 { margin: 4px 0 6px; font-size: 16.5px; }
.chapter-card p { font-size: 13.5px; color: var(--text-soft); margin: 0; }

.footer-note { margin-top: 80px; font-size: 12.5px; color: var(--text-soft); border-top: 1px solid var(--border); padding-top: 16px; }

/* ---------- Lab studio components (Decide → Build → Articulate) ---------- */
.lab-step {
  border: 1px solid var(--border); border-left: 4px solid var(--purple);
  border-radius: var(--radius); background: var(--bg-panel);
  padding: 18px 20px; margin: 24px 0;
}
.lab-step-head { font-weight: 750; font-size: 15px; margin-bottom: 10px; display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.lab-step-num {
  font-size: 11px; font-weight: 800; letter-spacing: .06em; text-transform: uppercase;
  background: var(--purple-soft); color: var(--purple); padding: 3px 10px; border-radius: 999px;
}
.lab-step-num.build { background: var(--green-soft); color: var(--green); }
.lab-step-num.decide { background: var(--purple-soft); color: var(--purple); }
.lab-step-num.articulate { background: var(--accent-soft); color: var(--accent); }

textarea.lab-commit {
  width: 100%; min-height: 84px; resize: vertical;
  font-family: inherit; font-size: 14px; line-height: 1.5;
  padding: 10px 12px; border-radius: 10px; border: 1px solid var(--border);
  background: var(--bg-inset); color: var(--text); margin: 8px 0 4px;
}
textarea.lab-commit:focus { outline: 2px solid var(--accent); border-color: transparent; }
.lab-commit-note { font-size: 12px; color: var(--text-soft); margin-bottom: 8px; }

details.hint { border-left: 4px solid var(--amber); }
details.hint > summary { color: var(--amber); }
details.model { border-left: 4px solid var(--green); }
details.model > summary { color: var(--green); }

.rubric {
  border: 1px dashed var(--border); border-radius: 10px;
  background: var(--bg-inset); padding: 12px 16px; margin: 12px 0; font-size: 13.5px;
}
.rubric .co-title { font-weight: 700; font-size: 12.5px; letter-spacing: .04em; text-transform: uppercase; color: var(--text-soft); margin-bottom: 6px; }
.rubric ul { margin: 0; padding-left: 20px; }

.lab-terminal {
  font-family: var(--font-mono); font-size: 13px;
  background: var(--code-bg); color: var(--code-text);
  border: 1px solid var(--code-border); border-radius: 10px;
  padding: 10px 14px; margin: 10px 0;
}
.lab-terminal::before { content: "$ "; color: var(--tok-s); }

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
}