/* ==========================================================================
   Spans All the Way Down — shared styles
   A standalone explainer series on Phoenix's tracing data model.
   No build step. Serve with: python3 -m http.server
   ========================================================================== */

:root {
  /* surfaces & ink (light) */
  --page: #f9f9f7;
  --surface: #fcfcfb;
  --surface-sunken: #f0efec;
  --ink: #0b0b0b;
  --ink-2: #52514e;
  --ink-3: #898781;
  --hairline: #e1e0d9;
  --baseline: #c3c2b7;
  --border: rgba(11, 11, 11, 0.1);

  /* accent */
  --accent: #1c5cab;
  --accent-ink: #104281;
  --accent-wash: rgba(42, 120, 214, 0.08);

  /* span kinds — validated categorical (legend order: agent, tool, llm, retriever) */
  --kind-agent: #2a78d6;
  --kind-tool: #eb6834;
  --kind-llm: #4a3aa7;
  --kind-retriever: #1baf7a;
  --kind-chain: #898781;
  --kind-agent-wash: rgba(42, 120, 214, 0.12);
  --kind-tool-wash: rgba(235, 104, 52, 0.12);
  --kind-llm-wash: rgba(74, 58, 167, 0.12);
  --kind-retriever-wash: rgba(27, 175, 122, 0.14);
  --kind-chain-wash: rgba(137, 135, 129, 0.14);

  /* status (fixed, never themed) */
  --status-good: #0ca30c;
  --status-warning: #fab219;
  --status-critical: #d03b3b;

  /* type */
  --sans: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --serif: "IBM Plex Serif", Georgia, "Times New Roman", serif;
  --mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --col: 46rem;
  --col-wide: 64rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --page: #0d0d0d;
    --surface: #1a1a19;
    --surface-sunken: #141413;
    --ink: #f4f4f2;
    --ink-2: #c3c2b7;
    --ink-3: #898781;
    --hairline: #2c2c2a;
    --baseline: #383835;
    --border: rgba(255, 255, 255, 0.1);

    --accent: #5598e7;
    --accent-ink: #86b6ef;
    --accent-wash: rgba(57, 135, 229, 0.14);

    --kind-agent: #3987e5;
    --kind-tool: #d95926;
    --kind-llm: #9085e9;
    --kind-retriever: #199e70;
    --kind-chain: #898781;
    --kind-agent-wash: rgba(57, 135, 229, 0.18);
    --kind-tool-wash: rgba(217, 89, 38, 0.18);
    --kind-llm-wash: rgba(144, 133, 233, 0.16);
    --kind-retriever-wash: rgba(25, 158, 112, 0.18);
    --kind-chain-wash: rgba(137, 135, 129, 0.18);

    --status-critical: #e66767;
  }
}

* { box-sizing: border-box; }

html { 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(--page);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.0625rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

/* --------------------------------------------------------------------------
   Series navigation
   -------------------------------------------------------------------------- */

.site-nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--page) 88%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--hairline);
  font-family: var(--sans);
}

.site-nav__inner {
  max-width: var(--col-wide);
  margin: 0 auto;
  padding: 0 1.25rem;
  display: flex;
  align-items: center;
  gap: 1.5rem;
  min-height: 3rem;
}

.site-nav__home {
  font-family: var(--mono);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--ink);
  text-decoration: none;
  white-space: nowrap;
  letter-spacing: 0.01em;
}
.site-nav__home:hover { color: var(--accent); }

.site-nav__parts {
  display: flex;
  gap: 0.25rem;
  list-style: none;
  margin: 0;
  padding: 0;
  overflow-x: auto;
}

.site-nav__parts a {
  display: inline-block;
  padding: 0.8rem 0.6rem;
  font-size: 0.8125rem;
  color: var(--ink-2);
  text-decoration: none;
  white-space: nowrap;
  border-bottom: 2px solid transparent;
}
.site-nav__parts a:hover { color: var(--ink); }
.site-nav__parts a[aria-current="page"] {
  color: var(--ink);
  font-weight: 600;
  border-bottom-color: var(--accent);
}
.site-nav__parts a .n {
  font-family: var(--mono);
  color: var(--ink-3);
  margin-right: 0.3em;
  font-size: 0.75rem;
}

/* --------------------------------------------------------------------------
   Page scaffold
   -------------------------------------------------------------------------- */

main {
  max-width: var(--col);
  margin: 0 auto;
  padding: 0 1.25rem 5rem;
}

.eyebrow {
  font-family: var(--mono);
  font-size: 0.8125rem;
  color: var(--ink-3);
  letter-spacing: 0.02em;
  margin: 3.5rem 0 0.75rem;
}
.eyebrow .k { color: var(--accent); }

h1 {
  font-family: var(--sans);
  font-weight: 650;
  font-size: clamp(1.9rem, 4.5vw, 2.6rem);
  line-height: 1.12;
  letter-spacing: -0.022em;
  margin: 0 0 1rem;
}

.dek {
  font-size: 1.2rem;
  line-height: 1.55;
  color: var(--ink-2);
  margin: 0 0 2.5rem;
}

h2 {
  font-family: var(--sans);
  font-weight: 640;
  font-size: 1.45rem;
  letter-spacing: -0.015em;
  line-height: 1.25;
  margin: 3rem 0 0.75rem;
}

h3 {
  font-family: var(--sans);
  font-weight: 620;
  font-size: 1.1rem;
  letter-spacing: -0.01em;
  margin: 2.25rem 0 0.5rem;
}

p, ul, ol { margin: 0 0 1.1rem; }
li { margin-bottom: 0.35rem; }

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { color: var(--accent-ink); }

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

strong { font-weight: 600; }

code {
  font-family: var(--mono);
  font-size: 0.855em;
  background: var(--surface-sunken);
  border: 1px solid var(--hairline);
  border-radius: 4px;
  padding: 0.08em 0.32em;
}

pre {
  font-family: var(--mono);
  font-size: 0.8125rem;
  line-height: 1.55;
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: 8px;
  padding: 1rem 1.15rem;
  overflow-x: auto;
  margin: 1.25rem 0 1.5rem;
}
pre code { background: none; border: none; padding: 0; font-size: inherit; }

hr {
  border: none;
  border-top: 1px solid var(--hairline);
  margin: 3rem 0;
}

/* prose asides — patio11-style parentheticals that earn their own block */
.aside {
  border-left: 2px solid var(--baseline);
  padding: 0.15rem 0 0.15rem 1.1rem;
  color: var(--ink-2);
  font-size: 0.975rem;
  margin: 1.4rem 0;
}

.callout {
  background: var(--accent-wash);
  border: 1px solid color-mix(in srgb, var(--accent) 25%, transparent);
  border-radius: 8px;
  padding: 0.9rem 1.15rem;
  margin: 1.5rem 0;
  font-size: 0.985rem;
}
.callout .label {
  display: block;
  font-family: var(--mono);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.35rem;
}

/* definition rows: term + prose */
.defs { margin: 1.5rem 0 2rem; border-top: 1px solid var(--hairline); }
.defs > div {
  display: grid;
  grid-template-columns: 9.5rem 1fr;
  gap: 1.25rem;
  padding: 0.9rem 0;
  border-bottom: 1px solid var(--hairline);
}
.defs dt {
  font-family: var(--mono);
  font-size: 0.85rem;
  font-weight: 600;
  padding-top: 0.15rem;
}
.defs dd { margin: 0; font-size: 0.985rem; }
.defs .tag {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  border-radius: 999px;
  padding: 0.1rem 0.55rem;
  margin-left: 0.4rem;
  vertical-align: 1px;
}
.tag--first-class { background: var(--kind-retriever-wash); color: var(--kind-retriever); }
.tag--derived { background: var(--kind-tool-wash); color: var(--kind-tool); }
.tag--convention { background: var(--kind-llm-wash); color: var(--kind-llm); }
@media (max-width: 640px) {
  .defs > div { grid-template-columns: 1fr; gap: 0.25rem; }
}

/* --------------------------------------------------------------------------
   Figures & widgets — breakout column
   -------------------------------------------------------------------------- */

.breakout {
  width: min(var(--col-wide), calc(100vw - 2.5rem));
  position: relative;
  left: 50%;
  transform: translateX(-50%);
}

figure.widget {
  margin: 2.25rem 0;
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: 10px;
  overflow: hidden;
}

figure.widget .widget__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem 1.25rem;
  padding: 0.85rem 1.15rem;
  border-bottom: 1px solid var(--hairline);
  font-family: var(--sans);
}
figure.widget .widget__title {
  font-size: 0.875rem;
  font-weight: 600;
}
figure.widget .widget__hint {
  font-size: 0.78rem;
  color: var(--ink-3);
}

figure.widget .widget__body { padding: 1.15rem; }

figure.widget figcaption {
  font-family: var(--sans);
  font-size: 0.8125rem;
  line-height: 1.55;
  color: var(--ink-2);
  padding: 0.85rem 1.15rem;
  border-top: 1px solid var(--hairline);
  background: var(--surface-sunken);
}

/* segmented control */
.seg {
  display: inline-flex;
  background: var(--surface-sunken);
  border: 1px solid var(--hairline);
  border-radius: 8px;
  padding: 2px;
  gap: 2px;
  font-family: var(--sans);
}
.seg button {
  appearance: none;
  border: none;
  background: transparent;
  font-family: var(--sans);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--ink-2);
  padding: 0.32rem 0.75rem;
  border-radius: 6px;
  cursor: pointer;
}
.seg button:hover { color: var(--ink); }
.seg button[aria-pressed="true"] {
  background: var(--surface);
  color: var(--ink);
  font-weight: 600;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}

/* legend */
.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 1.1rem;
  font-family: var(--sans);
  font-size: 0.78rem;
  color: var(--ink-2);
  align-items: center;
}
.legend .swatch {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 3px;
  margin-right: 0.4em;
  vertical-align: -1px;
}

/* kind color helpers */
.k-agent { --kc: var(--kind-agent); --kw: var(--kind-agent-wash); }
.k-llm { --kc: var(--kind-llm); --kw: var(--kind-llm-wash); }
.k-tool { --kc: var(--kind-tool); --kw: var(--kind-tool-wash); }
.k-retriever { --kc: var(--kind-retriever); --kw: var(--kind-retriever-wash); }
.k-chain { --kc: var(--kind-chain); --kw: var(--kind-chain-wash); }

/* --------------------------------------------------------------------------
   Comparison tables
   -------------------------------------------------------------------------- */

table.cmp {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--sans);
  font-size: 0.845rem;
  line-height: 1.45;
  margin: 1.5rem 0 2rem;
}
table.cmp th {
  text-align: left;
  font-weight: 600;
  font-size: 0.78rem;
  color: var(--ink-2);
  border-bottom: 1px solid var(--baseline);
  padding: 0.5rem 0.75rem 0.5rem 0;
  vertical-align: bottom;
}
table.cmp td {
  border-bottom: 1px solid var(--hairline);
  padding: 0.6rem 0.75rem 0.6rem 0;
  vertical-align: top;
}
table.cmp td:first-child, table.cmp th:first-child { padding-left: 0; }
table.cmp .mono { font-family: var(--mono); font-size: 0.8em; }

/* --------------------------------------------------------------------------
   Footer prev/next
   -------------------------------------------------------------------------- */

.pager {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-top: 4rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--hairline);
  font-family: var(--sans);
}
.pager a {
  display: block;
  text-decoration: none;
  border: 1px solid var(--hairline);
  border-radius: 10px;
  padding: 0.9rem 1.1rem;
  color: var(--ink);
  background: var(--surface);
}
.pager a:hover { border-color: var(--accent); }
.pager .dir {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-3);
  display: block;
  margin-bottom: 0.3rem;
}
.pager .t { font-weight: 600; font-size: 0.92rem; }
.pager .next { text-align: right; grid-column: 2; }

.colophon {
  margin-top: 2.5rem;
  font-family: var(--sans);
  font-size: 0.78rem;
  color: var(--ink-3);
}