/* The whole site's styles: no framework, no build step (Propshaft serves this
   file as-is). Colours are tokens with a light and a dark set; the reader's
   system setting picks one.

   1. Tokens   2. Base   3. Layout   4. Post list   5. Prose
   6. Code     7. Forms, buttons, tables, alerts
   7b. Article editor   7c. AI assistant              8. Utilities */

/* 1. Tokens ------------------------------------------------------------- */

:root {
  color-scheme: light dark;

  --font-body: Charter, "Bitstream Charter", "Sitka Text", Cambria, Georgia, serif;
  --font-ui: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-code: ui-monospace, "Cascadia Code", "Source Code Pro", Menlo, Consolas, monospace;

  --step--1: clamp(0.83rem, 0.8rem + 0.15vw, 0.9rem);
  --step-0: clamp(1.06rem, 1rem + 0.3vw, 1.2rem);
  --step-1: clamp(1.25rem, 1.15rem + 0.5vw, 1.5rem);
  --step-2: clamp(1.5rem, 1.3rem + 1vw, 2rem);
  --step-3: clamp(1.9rem, 1.5rem + 2vw, 2.75rem);

  --measure: 42rem;
  --space: 1.5rem;
  --radius: 6px;

  --bg: #fdfcfa;
  --text: #24221f;
  --muted: #6b665e;
  --rule: #e6e2da;
  --surface: #f4f1ec;
  --accent: #1f5fa8;
  --accent-text: #ffffff;
  --danger: #a3271f;
  --danger-bg: #fbeceb;
  --info-bg: #eaf1fa;

  /* Syntax colours */
  --code-comment: #6e6a63;
  --code-keyword: #a3271f;
  --code-string: #2f6f3e;
  --code-constant: #1f5fa8;
  --code-entity: #7a3e9d;
  --code-support: #8a5a00;
  --code-variable: #24221f;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17181b;
    --text: #e4e2dd;
    --muted: #9a968e;
    --rule: #2e3035;
    --surface: #202227;
    --accent: #7fb0ec;
    --accent-text: #0f1115;
    --danger: #f19087;
    --danger-bg: #3a1f1d;
    --info-bg: #1c2836;

    --code-comment: #8b8780;
    --code-keyword: #f19087;
    --code-string: #9fd3a6;
    --code-constant: #7fb0ec;
    --code-entity: #d3a6f0;
    --code-support: #e8c07a;
    --code-variable: #e4e2dd;
  }
}

/* 2. Base --------------------------------------------------------------- */

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

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: var(--step-0) / 1.65 var(--font-body);
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 {
  font-family: var(--font-ui);
  line-height: 1.2;
  letter-spacing: -0.01em;
  margin: 2em 0 0.6em;
}
h1 { font-size: var(--step-3); margin-top: 0; }
h2 { font-size: var(--step-2); }
h3 { font-size: var(--step-1); }
h4 { font-size: var(--step-0); }

p, ul, ol, blockquote, pre, table, figure { margin: 0 0 1.25em; }

a {
  color: var(--accent);
  text-underline-offset: 0.18em;
  text-decoration-thickness: 1px;
}
a:hover { text-decoration-thickness: 2px; }

img { max-width: 100%; height: auto; }

hr {
  border: 0;
  border-top: 1px solid var(--rule);
  margin: 2.5rem 0;
}

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

/* 3. Layout ------------------------------------------------------------- */

.site-header,
main,
.site-footer {
  width: min(100% - 2 * var(--space), var(--measure));
  margin-inline: auto;
}

.site-header {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.5rem 1.5rem;
  padding: 2rem 0 1.25rem;
  border-bottom: 1px solid var(--rule);
  font-family: var(--font-ui);

  .site-name {
    font-weight: 700;
    font-size: var(--step-1);
    color: var(--text);
    text-decoration: none;
  }

  nav ul {
    display: flex;
    gap: 1.25rem;
    margin: 0;
    padding: 0;
    list-style: none;
  }

  nav a {
    color: var(--muted);
    text-decoration: none;
    font-size: var(--step--1);
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;

    &:hover, &[aria-current="page"] { color: var(--text); }
  }
}

main {
  padding: 3rem 0 2rem;
  min-height: 60vh;
}

.site-footer {
  padding: 2rem 0 3rem;
  border-top: 1px solid var(--rule);
  color: var(--muted);
  font: var(--step--1) var(--font-ui);
  display: flex;
  align-items: center;
  justify-content: space-between;

  a { color: var(--muted); }
  a:hover { color: var(--text); }
  svg { width: 1.5rem; height: 1.5rem; display: block; }

  .footer-links { display: flex; align-items: center; gap: 1.25rem; }
}

/* 4. Post list ---------------------------------------------------------- */

.post-list {
  margin: 0;
  padding: 0;
  list-style: none;

  > li + li {
    border-top: 1px solid var(--rule);
    margin-top: 2rem;
    padding-top: 2rem;
  }

  h2 {
    margin: 0 0 0.3em;
    font-size: var(--step-2);

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

  p { margin: 0 0 0.5em; }
}

.post-meta {
  color: var(--muted);
  font: var(--step--1) var(--font-ui);

  a { color: inherit; }
  a:hover { color: var(--accent); }
}

.page-intro {
  margin-bottom: 3rem;

  h1 { margin-bottom: 0.3em; }
  p { color: var(--muted); font-size: var(--step-1); margin: 0; }
}

.pager {
  display: flex;
  justify-content: space-between;
  margin-top: 3rem;
  font-family: var(--font-ui);

  a { font-weight: 600; text-decoration: none; }
}

/* 5. Prose: an article body and the About page -------------------------- */

.article-header {
  margin-bottom: 2.5rem;

  .dek {
    color: var(--muted);
    font-size: var(--step-1);
    line-height: 1.4;
    margin: 0 0 0.75em;
  }
}

.prose {
  > :first-child { margin-top: 0; }

  ul, ol { padding-left: 1.4em; }
  li + li { margin-top: 0.3em; }

  blockquote {
    margin-inline: 0;
    padding-left: 1.25em;
    border-left: 3px solid var(--rule);
    color: var(--muted);
    font-style: italic;
  }

  table {
    width: 100%;
    border-collapse: collapse;
    font-size: var(--step--1);
    font-family: var(--font-ui);
  }
  th, td {
    padding: 0.5em 0.75em;
    border-bottom: 1px solid var(--rule);
    text-align: left;
  }
}

/* Markdown extras: heading anchors (commonmarker adds an empty link to each
   heading), task lists and footnotes. */
.prose {
  :is(h2, h3, h4) { position: relative; }
  .anchor {
    margin-left: 0.4em;
    color: var(--muted);
    text-decoration: none;
    opacity: 0;
  }
  .anchor::before { content: "#"; }
  :is(h2, h3, h4):hover .anchor,
  .anchor:focus-visible { opacity: 1; }

  li:has(> input[type="checkbox"]) { list-style: none; margin-left: -1.4em; }
  li > input[type="checkbox"] { margin-right: 0.5em; }

  .footnotes {
    margin-top: 3rem;
    padding-top: 1rem;
    border-top: 1px solid var(--rule);
    color: var(--muted);
    font-size: var(--step--1);
  }
  .footnote-ref a, .footnote-backref { text-decoration: none; }
}

/* 6. Code --------------------------------------------------------------- */

code, pre { font-family: var(--font-code); font-size: 0.86em; }

:not(pre) > code {
  background: var(--surface);
  padding: 0.1em 0.35em;
  border-radius: 4px;
}

pre {
  background: var(--surface);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  line-height: 1.5;
  tab-size: 2;
}

/* commonmarker emits TextMate scopes as classes; colour the broad ones and
   let anything nested inside a comment or string keep that colour. */
.syntax-highlighting {
  .comment { color: var(--code-comment); font-style: italic; }
  .keyword, .storage { color: var(--code-keyword); }
  .string { color: var(--code-string); }
  .constant { color: var(--code-constant); }
  .entity.name, .entity.other { color: var(--code-entity); }
  .support { color: var(--code-support); }
  .variable { color: var(--code-variable); }
  .comment *, .string * { color: inherit; }
}

/* 7. Forms, buttons, tables, alerts (admin and sign-in) ------------------ */

form { font-family: var(--font-ui); }

.field {
  margin-bottom: 1.25rem;

  label { display: block; font-weight: 600; margin-bottom: 0.35rem; font-size: var(--step--1); }
  .hint { margin: 0.35rem 0 0; }
}

input[type="text"], input[type="email"], input[type="password"], textarea {
  width: 100%;
  padding: 0.6rem 0.75rem;
  font: inherit;
  font-size: 1rem;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--rule);
  border-radius: var(--radius);

  &:focus { border-color: var(--accent); outline: 2px solid color-mix(in srgb, var(--accent) 30%, transparent); }
}

textarea.code { font-family: var(--font-code); font-size: 0.9rem; }

.checkbox {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
}

.button, button, input[type="submit"] {
  display: inline-block;
  padding: 0.5rem 1rem;
  font: 600 0.95rem var(--font-ui);
  color: var(--accent-text);
  background: var(--accent);
  border: 1px solid var(--accent);
  border-radius: var(--radius);
  text-decoration: none;
  cursor: pointer;

  &:hover { filter: brightness(1.08); }

  &.secondary {
    color: var(--text);
    background: transparent;
    border-color: var(--rule);
  }

  &.small { padding: 0.25rem 0.6rem; font-size: 0.85rem; }
}

.admin-table {
  width: 100%;
  border-collapse: collapse;
  font: var(--step--1) var(--font-ui);
  margin-bottom: 3rem;

  th, td { padding: 0.6rem 0.5rem; border-bottom: 1px solid var(--rule); text-align: left; vertical-align: middle; }
  th { color: var(--muted); font-weight: 600; }
  .actions { white-space: nowrap; text-align: right; }
}

.alert {
  padding: 0.75rem 1rem;
  margin-bottom: 1.5rem;
  border-radius: var(--radius);
  font: var(--step--1) var(--font-ui);
  background: var(--info-bg);

  &.danger { background: var(--danger-bg); color: var(--danger); }
  ul { margin: 0.5rem 0 0; padding-left: 1.25rem; }
}

/* 7b. Article editor: fields beside a live preview ------------------------ */

main.wide { width: min(100% - 2 * var(--space), 80rem); }

.editor-tabs {
  display: none;
  gap: 0.5rem;
  margin-bottom: 1.25rem;

  .tab {
    color: var(--muted);
    background: transparent;
    border-color: var(--rule);
  }
  .tab[aria-selected="true"] {
    color: var(--accent-text);
    background: var(--accent);
    border-color: var(--accent);
  }
}

.preview-label {
  margin: 0 0 1rem;
  color: var(--muted);
  font: 600 var(--step--1) var(--font-ui);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.editor-preview {
  /* It sits inside the form, whose UI font would otherwise leak into the
     article; match the published page. */
  font-family: var(--font-body);

  > article {
    padding: 1.5rem;
    border: 1px dashed var(--rule);
    border-radius: var(--radius);
  }
}
.editor.preview-stale .editor-preview > article { opacity: 0.6; }

/* The fields, then beside them (wide) or as tabs (narrow): the preview or
   the AI assistant. data-mode is write | preview | assistant. */
.editor-tabs { display: flex; }

@media (min-width: 900px) {
  .editor {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    grid-template-rows: auto 1fr;
    column-gap: 2.5rem;
    align-items: start;
  }
  .editor-write { grid-column: 1; grid-row: 1 / span 2; }
  .editor-tabs { grid-column: 2; grid-row: 1; }
  .editor-tabs .tab-write { display: none; }
  .editor-preview, .editor-assistant {
    grid-column: 2;
    grid-row: 2;
    position: sticky;
    top: 1rem;
    max-height: calc(100vh - 2rem);
    overflow-y: auto;
  }
  .editor[data-mode="assistant"] .editor-preview,
  .editor:not([data-mode="assistant"]) .editor-assistant { display: none; }
}

@media (max-width: 899.98px) {
  .editor:not([data-mode="write"]) .editor-write,
  .editor:not([data-mode="preview"]) .editor-preview,
  .editor:not([data-mode="assistant"]) .editor-assistant { display: none; }
}

.form-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
  .hint { margin: 0; }
}

.markdown-help {
  margin-top: 0.75rem;
  font-family: var(--font-ui);
  font-size: var(--step--1);

  summary { cursor: pointer; color: var(--accent); font-weight: 600; }

  table { width: 100%; border-collapse: collapse; margin-top: 0.75rem; }
  th, td { padding: 0.6rem 0.5rem; border-bottom: 1px solid var(--rule); text-align: left; vertical-align: top; }
  th { color: var(--muted); }
  td { width: 50%; }
  .example-name { display: block; margin-bottom: 0.3rem; font-weight: 600; }
  td pre { margin: 0; padding: 0.5rem 0.75rem; font-size: 0.85rem; white-space: pre-wrap; }
  td.prose { font-family: var(--font-body); }
  td.prose > :last-child { margin-bottom: 0; }
  td.prose :is(h2, h3) { margin: 0 0 0.3em; }
}

.draft-notice {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  margin-bottom: 2rem;
  border-radius: var(--radius);
  background: var(--info-bg);
  font: var(--step--1) var(--font-ui);

  .draft-actions { display: flex; gap: 0.5rem; align-items: center; }
}

/* 7c. AI assistant: editor panel and /admin/ai ----------------------------- */

.editor-assistant { font-family: var(--font-ui); }

.ai-spend {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  meter { width: 8rem; }
}

.ai-buttons { display: flex; flex-wrap: wrap; gap: 0.5rem; }

.ai-request {
  margin: 1rem 0 1.5rem;
  padding: 1rem 1.25rem;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background: var(--surface);
  font-family: var(--font-ui);
  font-size: var(--step--1);

  h3 { font-size: var(--step-0); margin: 1.25rem 0 0.5rem; }
  .prose { font-family: var(--font-body); font-size: var(--step-0); }
}

.ai-status { margin: 0 0 0.75rem; color: var(--muted); }
.ai-error { color: var(--danger); }

.ai-spinner {
  display: inline-block;
  width: 0.8em;
  height: 0.8em;
  margin-right: 0.4em;
  border: 2px solid var(--rule);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: ai-spin 0.8s linear infinite;
  vertical-align: -0.1em;
}
@keyframes ai-spin { to { transform: rotate(360deg); } }
@media (prefers-reduced-motion: reduce) { .ai-spinner { animation: none; } }

.ai-findings {
  margin: 0;
  padding: 0;
  list-style: none;

  > li { padding: 0.75rem 0; border-top: 1px solid var(--rule); }
  > li.applied { opacity: 0.55; }
  blockquote {
    margin: 0.5rem 0;
    padding-left: 0.75rem;
    border-left: 3px solid var(--rule);
    font-family: var(--font-body);
  }
  p { margin: 0.35rem 0; }
}

.ai-tag {
  display: inline-block;
  padding: 0.05rem 0.5rem;
  border-radius: 999px;
  background: var(--bg);
  border: 1px solid var(--rule);
  color: var(--muted);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}
.ai-tag-fact-check, .ai-tag-structure { color: var(--danger); }

.ai-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 0.4rem; }

.ai-options {
  margin: 0;
  padding: 0;
  list-style: none;
  > li {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 0.75rem;
    padding: 0.4rem 0;
    border-top: 1px solid var(--rule);
  }
}

.ai-sources { padding-left: 1.4em; li + li { margin-top: 0.3rem; } }

.ai-forms {
  display: grid;
  gap: 1rem 2.5rem;
  margin-bottom: 2rem;
  @media (min-width: 900px) { grid-template-columns: 1fr 1fr; }
  h2 { margin-top: 1rem; }
  select { width: 100%; padding: 0.5rem; font: 1rem var(--font-ui); }
}

/* 8. Utilities ---------------------------------------------------------- */

/* Secondary notes under fields and panels. */
.hint {
  color: var(--muted);
  font: var(--step--1) / 1.5 var(--font-ui);
}

/* button_to wraps its button in a form; keep it inline beside links. */
.inline { display: inline; }

.toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2rem;
}

.narrow { max-width: 24rem; }

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}