/* ==========================================================================
   Web Protocol Lab — light, flat, observation-lab theme
   白基調 / 直線 / 薄い罫線 / ログビューア風。丸角・グラデーション・シャドウは使わない。
   ========================================================================== */

:root {
  --bg: #f7f9fb;
  --surface: #ffffff;
  --surface-elevated: #eef2f6;
  --border: #d8e0e8;
  --border-strong: #b9c4cf;
  --text: #1c2733;
  --text-secondary: #46525f;
  --text-muted: #6e7a87;
  --accent: #0e7490;        /* cyan, darkened for white bg */
  --accent-blue: #0369a1;   /* blue, darkened for white bg */
  --success: #15803d;
  --warning: #b45309;
  --danger: #b91c1c;
  --code-bg: #101826;       /* terminal block on white page */
  --code-text: #d7e0ea;
  --code-muted: #64748b;
  --code-cyan: #22d3ee;
  --code-blue: #38bdf8;
  --font-mono: "SFMono-Regular", "Menlo", "Consolas", "Liberation Mono", monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN", "Noto Sans JP", sans-serif;
  font-size: 15px;
  line-height: 1.7;
}

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

/* --------------------------------------------------------------------------
   Layout
   -------------------------------------------------------------------------- */

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px;
}

main.container { padding-bottom: 64px; }

section { margin-top: 48px; }

h1 { font-size: 1.7rem; line-height: 1.3; margin: 0 0 8px; }
h2 {
  font-size: 1.15rem;
  margin: 0 0 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}
h2 .hash { color: var(--accent); margin-right: 8px; font-family: var(--font-mono); }
h3 { font-size: 1rem; margin: 26px 0 8px; color: var(--text); }

p { color: var(--text-secondary); }
p strong, li strong { color: var(--text); }
ul, ol { color: var(--text-secondary); padding-left: 1.4em; }
li { margin: 4px 0; }
li code, p code, td code {
  font-family: var(--font-mono);
  font-size: 0.86em;
  background: var(--surface-elevated);
  border: 1px solid var(--border);
  padding: 0 5px;
  color: var(--accent);
  white-space: nowrap;
}

/* --------------------------------------------------------------------------
   Nav
   -------------------------------------------------------------------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.nav {
  display: flex;
  align-items: center;
  gap: 20px;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px;
  min-height: 46px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.92rem;
  color: var(--text);
  white-space: nowrap;
}
.brand:hover { text-decoration: none; color: var(--text); }
.brand .dot {
  width: 8px; height: 8px;
  background: var(--accent);
}
.brand .lab { color: var(--accent); }

.nav-links {
  display: flex;
  align-items: stretch;
  gap: 2px;
  margin-left: auto;
  flex-wrap: wrap;
}
.nav-links a {
  display: flex;
  align-items: center;
  color: var(--text-secondary);
  font-size: 0.85rem;
  padding: 12px 10px;
  border-bottom: 2px solid transparent;
}
.nav-links a:hover { color: var(--text); background: var(--surface-elevated); text-decoration: none; }
.nav-links a.active { color: var(--accent); border-bottom-color: var(--accent); }

.nav-toggle {
  display: none;
  margin-left: auto;
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
  padding: 5px 12px;
  font-size: 0.9rem;
  cursor: pointer;
}

/* --------------------------------------------------------------------------
   Hero / page header
   -------------------------------------------------------------------------- */

.hero {
  padding: 44px 0 32px;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}
.hero h1 {
  font-size: 1.9rem;
  letter-spacing: -0.01em;
  font-family: var(--font-mono);
}
.hero h1 .accent { color: var(--accent); }
.hero .tagline {
  max-width: 720px;
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin: 6px 0;
}
.hero .meta {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 16px;
}

.page-header {
  padding: 32px 0 24px;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}
.page-header .crumb {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  margin-bottom: 4px;
}
.page-header h1 { font-family: var(--font-mono); }
.page-header .lede { max-width: 760px; margin-top: 8px; font-size: 0.95rem; }
.page-header .meta { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 12px; }

/* --------------------------------------------------------------------------
   Badges — 角のないラベル
   -------------------------------------------------------------------------- */

.badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  padding: 1px 8px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-muted);
  white-space: nowrap;
}
.badge.rfc { color: var(--accent-blue); border-color: #b6d9ef; background: #f0f7fc; }
.badge.ok { color: var(--success); border-color: #b7e0c8; background: #f0faf4; }
.badge.warn { color: var(--warning); border-color: #f0d9a8; background: #fdf8ec; }
.badge.danger { color: var(--danger); border-color: #f2c1c1; background: #fdf1f1; }
.badge.cyan { color: var(--accent); border-color: #a8dbe6; background: #eef9fb; }
a.badge:hover { text-decoration: none; color: var(--accent); border-color: var(--accent); }

/* --------------------------------------------------------------------------
   Cards — 白パネル + 1px罫線
   -------------------------------------------------------------------------- */

.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}
.grid.cols-2 { grid-template-columns: repeat(2, 1fr); }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 12px 14px;
  display: flex;
  flex-direction: column;
  gap: 5px;
}
a.card { color: inherit; }
a.card:hover {
  text-decoration: none;
  border-color: var(--accent);
}

.card .card-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  color: var(--text);
  font-size: 0.92rem;
}

/* ステータスコードはログのラベル風に */
.card .card-title .code {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 700;
  padding: 0 6px;
  border: 1px solid var(--border-strong);
  background: var(--surface-elevated);
  color: var(--text);
}
.card .card-title .code.s2 { color: var(--success); border-color: #b7e0c8; background: #f0faf4; }
.card .card-title .code.s3 { color: var(--accent-blue); border-color: #b6d9ef; background: #f0f7fc; }
.card .card-title .code.s4 { color: var(--warning); border-color: #f0d9a8; background: #fdf8ec; }
.card .card-title .code.s5 { color: var(--danger); border-color: #f2c1c1; background: #fdf1f1; }

.card .card-desc { font-size: 0.84rem; color: var(--text-secondary); flex: 1; }
.card .card-url {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  color: var(--text-muted);
  overflow-wrap: anywhere;
}
.card .card-observe { font-size: 0.78rem; color: var(--text-muted); }
.card .card-observe b { color: var(--accent); font-weight: 500; }

.card.planned { border-style: dashed; background: var(--bg); }

/* --------------------------------------------------------------------------
   Code blocks / response panels — ターミナル風の黒パネル
   -------------------------------------------------------------------------- */

pre.code {
  position: relative;
  background: var(--code-bg);
  border-left: 2px solid var(--accent);
  padding: 12px 14px;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.6;
  color: var(--code-text);
  margin: 10px 0;
}
pre.code .comment { color: var(--code-muted); }
pre.code .prompt { color: var(--code-cyan); user-select: none; }

.code-label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-top: 14px;
}

.copy-btn {
  position: absolute;
  top: 6px;
  right: 6px;
  background: #1c2733;
  color: #8b98a5;
  border: 1px solid #334155;
  font-size: 0.7rem;
  font-family: var(--font-mono);
  padding: 2px 9px;
  cursor: pointer;
  opacity: 0;
}
pre.code:hover .copy-btn { opacity: 1; }
.copy-btn:hover { color: var(--code-text); border-color: var(--code-cyan); }
.copy-btn.copied { color: #34d399; border-color: #34d399; opacity: 1; }

/* Response preview panel — 受信ログ風 */
.response-panel {
  background: var(--code-bg);
  border-left: 2px solid var(--code-blue);
  padding: 12px 14px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.6;
  overflow-x: auto;
  margin: 10px 0;
  white-space: pre;
  color: var(--code-muted);
}
.response-panel .status { color: var(--code-cyan); font-weight: 600; }
.response-panel .hname { color: var(--code-blue); }

/* Callout note */
.note {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 2px solid var(--warning);
  padding: 10px 14px;
  font-size: 0.87rem;
  color: var(--text-secondary);
  margin: 14px 0;
}
.note.info { border-left-color: var(--accent-blue); }
.note b { color: var(--text); }

/* --------------------------------------------------------------------------
   Observation checklist table
   -------------------------------------------------------------------------- */

.obs-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
  margin: 10px 0;
}
.obs-table th, .obs-table td {
  text-align: left;
  padding: 8px 12px;
  border: 1px solid var(--border);
  vertical-align: top;
}
.obs-table th {
  background: var(--surface-elevated);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 0.76rem;
  font-weight: 600;
  white-space: nowrap;
}
.obs-table td { color: var(--text-secondary); background: var(--surface); }

.table-wrap { overflow-x: auto; }

/* --------------------------------------------------------------------------
   Sequence diagrams (rendered by main.js from pre.seq)
   -------------------------------------------------------------------------- */

.seq-figure {
  margin: 18px 0;
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 14px;
}
.seq-figure figcaption {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  margin-bottom: 8px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 6px;
}
pre.seq {
  /* fallback style when JS is disabled */
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
  overflow-x: auto;
  margin: 0;
}
.seq-diagram { min-width: 0; }
.seq-toolbar {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 6px;
  margin: 2px 0 10px;
}
.seq-control {
  appearance: none;
  border: 1px solid var(--border-strong);
  border-radius: 0;
  background: var(--surface);
  color: var(--text-secondary);
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  line-height: 1.4;
  padding: 4px 9px;
}
.seq-control:hover { color: var(--accent-blue); border-color: var(--accent-blue); }
.seq-control:focus-visible { outline: 2px solid var(--accent-blue); outline-offset: 2px; }
.seq-control-primary {
  background: var(--accent-blue);
  border-color: var(--accent-blue);
  color: #fff;
  min-width: 92px;
}
.seq-control-primary:hover { background: var(--accent); border-color: var(--accent); color: #fff; }
.seq-status {
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  margin-left: auto;
}
.seq-canvas { min-width: 0; overflow-x: auto; }
.seq-svg { width: 100%; height: auto; display: block; min-width: 520px; }
.seq-svg .participant-box { fill: var(--surface-elevated); stroke: var(--border-strong); }
.seq-svg .participant-label { fill: var(--text); font-family: var(--font-mono); font-size: 13px; font-weight: 600; }
.seq-svg .lifeline { stroke: var(--border-strong); stroke-dasharray: 4 4; }
.seq-svg .msg-line { stroke: var(--accent-blue); stroke-width: 1.2; }
.seq-svg .msg-line.dashed { stroke-dasharray: 5 4; }
.seq-svg .msg-label { fill: var(--text-secondary); font-family: var(--font-mono); font-size: 12px; }
.seq-svg .note-label { fill: var(--text-muted); font-family: var(--font-mono); font-size: 11.5px; font-style: italic; }
.seq-svg .arrow-head { fill: var(--accent-blue); }
.seq-svg .seq-row { opacity: 1; transition: opacity 180ms ease-out; }
.seq-diagram.is-animating .seq-row { opacity: 0; }
.seq-diagram.is-animating .seq-row.is-visible { opacity: 1; }
.seq-diagram.is-animating .seq-row.is-current .msg-line { stroke-width: 2; }
.seq-diagram.is-animating .seq-row.is-current .msg-label {
  fill: var(--text);
  font-weight: 600;
}
.seq-diagram.is-animating .seq-row.is-current .note-label {
  fill: var(--accent);
  font-weight: 600;
}
.seq-svg .seq-packet {
  fill: var(--accent);
  opacity: 0;
  stroke: var(--surface);
  stroke-width: 2;
}
.seq-diagram.is-animating .seq-row.is-current .seq-packet { opacity: 1; }
.seq-svg .seq-participant .participant-box,
.seq-svg .seq-participant .participant-label { transition: fill 180ms ease-out, stroke 180ms ease-out; }
.seq-svg .seq-participant.is-active .participant-box {
  fill: #e2f4f7;
  stroke: var(--accent);
  stroke-width: 1.5;
}
.seq-svg .seq-participant.is-active .participant-label { fill: var(--accent); }

@media (prefers-reduced-motion: reduce) {
  .seq-svg .seq-row,
  .seq-svg .seq-participant .participant-box,
  .seq-svg .seq-participant .participant-label { transition: none; }
  .seq-svg .seq-packet { display: none; }
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */

.site-footer {
  border-top: 1px solid var(--border);
  padding: 28px 0 44px;
  margin-top: 56px;
  background: var(--surface);
}
.site-footer .container {
  display: flex;
  flex-wrap: wrap;
  gap: 24px;
  justify-content: space-between;
  align-items: flex-start;
}
.site-footer .footer-brand { color: var(--text); font-weight: 600; font-family: var(--font-mono); font-size: 0.9rem; }
.site-footer .footer-brand .lab { color: var(--accent); }
.site-footer .footer-note { font-size: 0.79rem; color: var(--text-muted); max-width: 460px; margin-top: 6px; }
.site-footer nav { display: flex; flex-wrap: wrap; gap: 6px 18px; }
.site-footer nav a { color: var(--text-secondary); font-size: 0.84rem; }

/* --------------------------------------------------------------------------
   Responsive
   -------------------------------------------------------------------------- */

@media (max-width: 900px) {
  .grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
  .grid, .grid.cols-2 { grid-template-columns: 1fr; }
  .hero h1 { font-size: 1.5rem; }
  .nav { min-height: 42px; }
  .nav-toggle { display: block; }
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 4px 16px 12px;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 10px 12px; border-bottom: none; }
  .nav-links a.active { background: var(--surface-elevated); }
  .seq-status { flex-basis: 100%; margin-left: 0; }
}