/* Shared styles for learn-go-for-canton.
   Go-teal accent on a dark surface. Designed to feel like a terminal meets
   a well-typeset engineering doc. Used by every page in this course. */

:root {
  --bg: #0d1117;
  --bg-surface: #161b22;
  --bg-elevated: #1f2632;
  --bg-code: #0a0f14;
  --border: #30363d;
  --border-strong: #484f58;
  --text: #e6edf3;
  --text-muted: #8d96a0;
  --text-faint: #6e7681;

  /* Go brand cyan + a warm companion for contrast */
  --accent: #00add8;
  --accent-hover: #3dd1f5;
  --accent-soft: rgba(0, 173, 216, 0.12);
  --warm: #f2cc60;
  --warm-soft: rgba(242, 204, 96, 0.12);

  --ok: #3fb950;
  --warn: #d29922;
  --err: #f85149;

  --radius: 10px;
  --radius-sm: 4px;

  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Fraunces', 'Iowan Old Style', 'Palatino', 'Georgia', serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'SF Mono', Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-body);
  background:
    radial-gradient(circle at 15% 0%, rgba(0, 173, 216, 0.06), transparent 45%),
    radial-gradient(circle at 85% 100%, rgba(242, 204, 96, 0.03), transparent 45%),
    var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

/* Site-wide navigation bar (top of every page) */
.site-nav {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.85rem 1.5rem;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border);
  font-size: 0.88rem;
  color: var(--text-muted);
  flex-wrap: wrap;
}
.site-nav a {
  color: var(--text-muted);
  text-decoration: none;
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-sm);
  transition: background 0.15s ease, color 0.15s ease;
}
.site-nav a:hover { background: var(--accent-soft); color: var(--accent); }
.site-nav .nav-sep { color: var(--text-faint); }
.site-nav .nav-current {
  color: var(--text);
  padding: 0.15rem 0.5rem;
  font-weight: 500;
}
.site-nav .nav-spacer { flex: 1; }
.site-nav .nav-home {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  color: var(--accent);
  font-weight: 500;
}

/* Layout containers */
.wrap { max-width: 880px; margin: 0 auto; padding: 0 1.5rem; }
.wrap-wide { max-width: 1100px; margin: 0 auto; padding: 0 1.5rem; }

/* Headings */
h1, h2, h3, h4 {
  font-family: var(--font-body);
  letter-spacing: -0.015em;
  line-height: 1.2;
  color: var(--text);
}
h1 { font-size: clamp(1.9rem, 3.6vw, 2.5rem); margin: 2rem 0 1rem; }
h2 {
  font-size: 1.6rem;
  margin: 3rem 0 1rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--border);
}
h3 { font-size: 1.2rem; margin: 2rem 0 0.75rem; color: var(--accent); }
h4 { font-size: 1rem; margin: 1.5rem 0 0.5rem; color: var(--warm); }

p { margin: 0 0 1rem; }
a { color: var(--accent); }
a:hover { color: var(--accent-hover); }
ul, ol { padding-left: 1.3rem; }
li { margin: 0.3rem 0; }
strong { color: var(--text); }
em { color: var(--warm); font-style: italic; }

/* Kicker / meta */
.kicker {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--accent);
  font-weight: 600;
  margin: 0 0 0.75rem;
}

/* Lesson content shell */
.lesson {
  padding: 2.5rem 0 5rem;
}
.lesson .lede {
  font-size: 1.1rem;
  color: var(--text-muted);
  max-width: 65ch;
  margin: 0 0 2.5rem;
  border-left: 3px solid var(--accent);
  padding-left: 1rem;
}

/* Code */
code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--bg-code);
  color: var(--warm);
  padding: 0.12rem 0.35rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}
pre {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  background: var(--bg-code);
  color: var(--text);
  padding: 1rem 1.1rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  overflow-x: auto;
  line-height: 1.55;
  margin: 1rem 0;
}
pre code {
  background: none;
  border: none;
  padding: 0;
  color: inherit;
  font-size: inherit;
}

/* Basic syntax highlighting via classes */
.tok-kw { color: #ff7b72; }        /* keyword */
.tok-type { color: #79c0ff; }       /* type name */
.tok-fn { color: #d2a8ff; }         /* function */
.tok-str { color: #a5d6ff; }        /* string literal */
.tok-num { color: #ffa657; }        /* number */
.tok-cmt { color: #8b949e; font-style: italic; } /* comment */
.tok-op { color: #e6edf3; }         /* operator */
.tok-lit { color: #56d364; }        /* literal true/false/nil */

/* Callout boxes */
.callout {
  padding: 1rem 1.15rem;
  border-radius: var(--radius);
  margin: 1.25rem 0;
  border: 1px solid var(--border);
  background: var(--bg-surface);
}
.callout.note { border-left: 3px solid var(--accent); background: var(--accent-soft); }
.callout.warn { border-left: 3px solid var(--warn); background: rgba(210, 153, 34, 0.1); }
.callout.canton { border-left: 3px solid var(--warm); background: var(--warm-soft); }
.callout h4 { margin-top: 0; color: inherit; }
.callout p:last-child { margin-bottom: 0; }
.callout .callout-tag {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  font-weight: 600;
  margin-bottom: 0.4rem;
  opacity: 0.85;
}
.callout.note .callout-tag { color: var(--accent); }
.callout.warn .callout-tag { color: var(--warn); }
.callout.canton .callout-tag { color: var(--warm); }

/* Comparison tables (Python/JS/Hack → Go) */
table.compare {
  width: 100%;
  border-collapse: collapse;
  margin: 1.25rem 0;
  font-size: 0.92rem;
}
table.compare th, table.compare td {
  padding: 0.6rem 0.8rem;
  border: 1px solid var(--border);
  text-align: left;
  vertical-align: top;
}
table.compare th {
  background: var(--bg-elevated);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
table.compare code { background: var(--bg-code); }

/* Checkable item lists */
.checklist {
  list-style: none;
  padding: 0;
}
.checklist li {
  padding: 0.5rem 0.75rem;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  margin: 0.35rem 0;
  cursor: pointer;
  user-select: none;
  transition: background 0.15s ease, border-color 0.15s ease;
}
.checklist li:hover { border-color: var(--accent); }
.checklist li.done {
  background: var(--accent-soft);
  border-color: var(--accent);
  text-decoration: line-through;
  color: var(--text-muted);
}
.checklist li::before {
  content: "◯ ";
  color: var(--text-faint);
  font-family: var(--font-mono);
}
.checklist li.done::before { content: "✓ "; color: var(--accent); }

/* Prev/next nav at page bottom */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin: 3.5rem 0 0;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  flex-wrap: wrap;
}
.lesson-nav a {
  padding: 0.7rem 1rem;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--text);
  font-size: 0.92rem;
  transition: border-color 0.15s ease, background 0.15s ease;
  max-width: 45%;
}
.lesson-nav a:hover { border-color: var(--accent); background: var(--accent-soft); }
.lesson-nav a .label {
  display: block;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-faint);
  margin-bottom: 0.15rem;
}
.lesson-nav a.prev { text-align: left; }
.lesson-nav a.next { text-align: right; margin-left: auto; }

/* Mark-as-complete button */
.complete-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.65rem 1.1rem;
  background: var(--accent);
  color: var(--bg);
  border: none;
  border-radius: var(--radius);
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
  margin: 1.5rem 0;
  font-family: inherit;
  transition: background 0.15s ease, transform 0.1s ease;
}
.complete-btn:hover { background: var(--accent-hover); }
.complete-btn:active { transform: translateY(1px); }
.complete-btn.done {
  background: var(--ok);
  color: var(--bg);
}

/* Buttons (generic) */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.55rem 0.95rem;
  background: var(--bg-elevated);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  cursor: pointer;
  font-family: inherit;
  text-decoration: none;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn.primary {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
}
.btn.primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); color: var(--bg); }

/* Keyboard key style */
kbd {
  font-family: var(--font-mono);
  font-size: 0.78em;
  background: var(--bg-elevated);
  border: 1px solid var(--border-strong);
  border-bottom-width: 2px;
  border-radius: 3px;
  padding: 0.08rem 0.35rem;
  color: var(--text);
}

/* Utility */
.muted { color: var(--text-muted); }
.mono { font-family: var(--font-mono); }
.small { font-size: 0.88rem; }
.tiny { font-size: 0.78rem; }
.hstack { display: flex; gap: 0.75rem; align-items: center; flex-wrap: wrap; }
.vstack { display: flex; flex-direction: column; gap: 0.75rem; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; }
@media (max-width: 640px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
}