/* FrameAI Eurocode Worked Examples — Engineering Dark Theme
   Fonts: Syne (headings) + Satoshi (body) + JetBrains Mono (formulas)
*/

@import url('https://fonts.googleapis.com/css2?family=Syne:wght@400;600;700;800&family=Satoshi:wght@300;400;500&family=JetBrains+Mono:wght@300;400;500&display=swap');

/* ── Design tokens ─────────────────────────────────────────────────────── */
:root {
  --bg:         #0c0e14;
  --surface:    #12151e;
  --surface2:   #181c27;
  --border:     rgba(245, 158, 11, 0.12);
  --border-hi:  rgba(245, 158, 11, 0.30);
  --amber:      #f59e0b;
  --amber-dim:  rgba(245, 158, 11, 0.15);
  --amber-glow: rgba(245, 158, 11, 0.25);
  --green:      #10b981;
  --green-dim:  rgba(16, 185, 129, 0.12);
  --red:        #ef4444;
  --red-dim:    rgba(239, 68, 68, 0.12);
  --text-hi:    #f0f2f8;
  --text-mid:   #8892a4;
  --text-lo:    #525b70;
  --mono:       'JetBrains Mono', monospace;
  --sans:       'Satoshi', sans-serif;
  --display:    'Syne', sans-serif;
}

/* ── Base ───────────────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  background: var(--bg);
  color: var(--text-hi);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

::selection { background: var(--amber-dim); color: var(--amber); }

::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--surface); }
::-webkit-scrollbar-thumb { background: var(--border-hi); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--amber); }

/* ── Page header ────────────────────────────────────────────────────────── */
.ec-header {
  border-bottom: 1px solid var(--border);
  padding: 2rem 3rem;
  background: linear-gradient(180deg, var(--surface) 0%, var(--bg) 100%);
}

.ec-header-inner {
  max-width: 1100px;
  margin: 0 auto;
}

.ec-breadcrumb {
  font-family: var(--mono);
  font-size: 0.7rem;
  color: var(--text-lo);
  letter-spacing: 0.06em;
  margin-bottom: 1rem;
}

.ec-breadcrumb a {
  color: var(--text-mid);
  text-decoration: none;
  transition: color 0.15s;
}
.ec-breadcrumb a:hover { color: var(--amber); }

.ec-category-badge {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  padding: 0.2rem 0.6rem;
  border-radius: 2px;
  margin-bottom: 1rem;
  text-transform: uppercase;
}

.ec-title {
  font-family: var(--display);
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 700;
  color: var(--text-hi);
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin-bottom: 0.5rem;
}

.ec-ref {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--text-mid);
  margin-bottom: 0.5rem;
}

.ec-ref span { color: var(--amber); }

/* ── Verdict banner ─────────────────────────────────────────────────────── */
.ec-verdict {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.45rem 1rem;
  border-radius: 3px;
  font-family: var(--mono);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  margin-bottom: 0.5rem;
}

.ec-verdict.pass {
  background: var(--green-dim);
  border: 1px solid rgba(16, 185, 129, 0.35);
  color: var(--green);
}

.ec-verdict.fail {
  background: var(--red-dim);
  border: 1px solid rgba(239, 68, 68, 0.35);
  color: var(--red);
}

.ec-verdict.amber {
  background: var(--amber-dim);
  border: 1px solid var(--border-hi);
  color: var(--amber);
}

.ec-util-bar {
  margin: 0.75rem 0;
  height: 4px;
  background: var(--surface2);
  border-radius: 2px;
  overflow: hidden;
  width: 100%;
  max-width: 320px;
}

.ec-util-fill {
  height: 100%;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--amber) 0%, #fb923c 100%);
  transition: width 0.4s ease;
}

.ec-util-fill.low { background: linear-gradient(90deg, var(--green) 0%, #34d399 100%); }
.ec-util-fill.high { background: linear-gradient(90deg, var(--red) 0%, #f87171 100%); }

.ec-util-label {
  font-family: var(--mono);
  font-size: 0.7rem;
  color: var(--text-mid);
}

/* ── Problem statement ───────────────────────────────────────────────────── */
.ec-problem {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--amber);
  border-radius: 4px;
  padding: 1.25rem 1.5rem;
  margin: 1.5rem 0;
  font-family: var(--sans);
  font-size: 0.875rem;
  color: var(--text-hi);
  line-height: 1.7;
  max-width: 1100px;
}

.ec-problem-label {
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 0.5rem;
}

/* ── Steps ──────────────────────────────────────────────────────────────── */
.ec-steps {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 3rem 4rem;
}

.ec-steps-header {
  font-family: var(--display);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-lo);
  padding: 1.5rem 0 1rem;
  border-top: 1px solid var(--border);
  margin-top: 1.5rem;
}

.ec-step {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 0;
  border: 1px solid var(--border);
  border-radius: 4px;
  margin: 1rem 0;
  overflow: hidden;
  background: var(--surface);
  transition: border-color 0.2s;
}

.ec-step:hover { border-color: var(--border-hi); }

.ec-step-clause {
  padding: 1.5rem;
  border-right: 1px solid var(--border);
  background: var(--surface2);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.ec-clause-badge {
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  padding: 0.25rem 0.5rem;
  border-radius: 2px;
  background: var(--amber-dim);
  color: var(--amber);
  text-align: center;
  display: inline-block;
  width: fit-content;
}

.ec-step-title {
  font-family: var(--display);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-hi);
  line-height: 1.3;
}

.ec-step-content { padding: 1.5rem; }

.ec-step h4 {
  font-family: var(--sans);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-lo);
  margin: 0.75rem 0 0.4rem;
}

.ec-step h4:first-child { margin-top: 0; }

.ec-derivation {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--text-mid);
  line-height: 1.8;
  white-space: pre-wrap;
  background: var(--bg);
  padding: 0.75rem 1rem;
  border-radius: 3px;
  border: 1px solid var(--border);
  margin: 0.5rem 0;
}

.ec-formula {
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--amber);
  background: var(--surface2);
  border: 1px solid var(--border-hi);
  padding: 0.75rem 1rem;
  border-radius: 3px;
  margin: 0.5rem 0;
  text-align: center;
  letter-spacing: 0.02em;
}

.ec-result {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--text-hi);
  font-weight: 500;
  background: linear-gradient(135deg, var(--surface2), var(--surface));
  border: 1px solid var(--border-hi);
  padding: 0.6rem 1rem;
  border-radius: 3px;
  margin-top: 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.ec-result::before {
  content: '→';
  color: var(--amber);
  font-size: 0.9rem;
}

/* ── Calc widget ────────────────────────────────────────────────────────── */
.calc-widget-wrapper {
  background: var(--surface);
  border: 1px solid var(--border-hi);
  border-radius: 6px;
  padding: 1.5rem;
  margin: 2rem 0;
  max-width: 1100px;
}

.calc-widget-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.calc-widget-title {
  font-family: var(--display);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-hi);
}

.calc-widget-badge {
  font-family: var(--mono);
  font-size: 0.6rem;
  padding: 0.15rem 0.45rem;
  border-radius: 2px;
  background: var(--amber-dim);
  color: var(--amber);
  letter-spacing: 0.06em;
}

.calc-widget {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1rem;
  min-height: 60px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.calc-widget .ec-input-group {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.calc-widget label {
  font-family: var(--mono);
  font-size: 0.65rem;
  color: var(--text-mid);
  letter-spacing: 0.05em;
}

.calc-widget input {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 3px;
  color: var(--text-hi);
  font-family: var(--mono);
  font-size: 0.8rem;
  padding: 0.4rem 0.6rem;
  width: 100px;
  transition: border-color 0.15s;
}

.calc-widget input:focus {
  outline: none;
  border-color: var(--amber);
}

.calc-widget button {
  background: var(--amber);
  color: #0c0e14;
  font-family: var(--sans);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.5rem 1.2rem;
  border: none;
  border-radius: 3px;
  cursor: pointer;
  transition: opacity 0.15s;
}

.calc-widget button:hover { opacity: 0.85; }

.calc-widget button:disabled { opacity: 0.4; cursor: not-allowed; }

.calc-widget-result {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--green);
  padding: 0.5rem 0;
}

.calc-widget-result.error { color: var(--red); }

/* ── Related sidebar ─────────────────────────────────────────────────────── */
.ec-related {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 3rem 4rem;
}

.ec-related h3 {
  font-family: var(--display);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-lo);
  margin-bottom: 1rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

.ec-related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 0.75rem;
}

.ec-related-card {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 4px;
  text-decoration: none;
  transition: border-color 0.2s, transform 0.15s;
}

.ec-related-card:hover {
  border-color: var(--border-hi);
  transform: translateX(3px);
}

.ec-related-icon {
  width: 32px;
  height: 32px;
  border-radius: 3px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 500;
  flex-shrink: 0;
}

.ec-related-info { flex: 1; }

.ec-related-name {
  font-family: var(--sans);
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-hi);
  line-height: 1.3;
}

.ec-related-ref {
  font-family: var(--mono);
  font-size: 0.65rem;
  color: var(--text-lo);
  margin-top: 0.15rem;
}

.ec-related-arrow {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--amber);
  opacity: 0;
  transition: opacity 0.15s;
}

.ec-related-card:hover .ec-related-arrow { opacity: 1; }

/* ── Index page ─────────────────────────────────────────────────────────── */
.ec-index-hero {
  padding: 5rem 3rem 3rem;
  text-align: center;
  background: linear-gradient(180deg, var(--surface) 0%, var(--bg) 100%);
  border-bottom: 1px solid var(--border);
}

.ec-index-hero h1 {
  font-family: var(--display);
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 800;
  color: var(--text-hi);
  letter-spacing: -0.03em;
  margin-bottom: 1rem;
}

.ec-index-hero p {
  font-size: 1rem;
  color: var(--text-mid);
  max-width: 560px;
  margin: 0 auto 2rem;
  line-height: 1.6;
}

.ec-stats {
  display: flex;
  gap: 3rem;
  justify-content: center;
  margin-top: 2rem;
}

.ec-stat-val {
  font-family: var(--display);
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--amber);
  line-height: 1;
}

.ec-stat-lbl {
  font-family: var(--mono);
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-lo);
  margin-top: 0.3rem;
}

.ec-grid {
  max-width: 1100px;
  margin: 0 auto;
  padding: 2rem 3rem 4rem;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: 6px;
  overflow: hidden;
}

.ec-card {
  background: var(--surface);
  padding: 1.5rem;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: background 0.2s;
  position: relative;
}

.ec-card:hover { background: var(--surface2); }

.ec-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem;
}

.ec-card-badge {
  font-family: var(--mono);
  font-size: 0.6rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  padding: 0.2rem 0.5rem;
  border-radius: 2px;
  text-transform: uppercase;
  flex-shrink: 0;
}

.ec-card-verdict {
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 500;
  padding: 0.2rem 0.5rem;
  border-radius: 2px;
  flex-shrink: 0;
}

.ec-card-verdict.pass { background: var(--green-dim); color: var(--green); }
.ec-card-verdict.fail { background: var(--red-dim); color: var(--red); }
.ec-card-verdict.amber { background: var(--amber-dim); color: var(--amber); }

.ec-card-title {
  font-family: var(--display);
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-hi);
  line-height: 1.3;
}

.ec-card-ref {
  font-family: var(--mono);
  font-size: 0.7rem;
  color: var(--text-lo);
}

.ec-card-util {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-family: var(--mono);
  font-size: 0.75rem;
}

.ec-card-util-bar {
  flex: 1;
  height: 3px;
  background: var(--surface2);
  border-radius: 2px;
  overflow: hidden;
}

.ec-card-util-fill {
  height: 100%;
  border-radius: 2px;
}

.ec-card-meta {
  display: flex;
  gap: 1rem;
  font-family: var(--mono);
  font-size: 0.65rem;
  color: var(--text-lo);
  border-top: 1px solid var(--border);
  padding-top: 0.75rem;
  margin-top: auto;
}

.ec-card-arrow {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--amber);
  margin-left: auto;
  opacity: 0;
  transition: opacity 0.15s;
}

.ec-card:hover .ec-card-arrow { opacity: 1; }

/* ── JSON-LD HowTo schema ───────────────────────────────────────────────── */
.ec-cta-section {
  max-width: 1100px;
  margin: 0 auto;
  padding: 2rem 3rem;
  text-align: center;
  border-top: 1px solid var(--border);
}

/* ── Responsive ─────────────────────────────────────────────────────────── */
@media (max-width: 768px) {
  .ec-header, .ec-steps, .ec-related, .ec-grid { padding-left: 1.25rem; padding-right: 1.25rem; }
  .ec-step { grid-template-columns: 1fr; }
  .ec-step-clause { border-right: none; border-bottom: 1px solid var(--border); padding: 1rem 1.25rem; }
  .ec-stats { gap: 1.5rem; }
  .ec-stat-val { font-size: 1.8rem; }
}

@media (max-width: 480px) {
  .ec-grid { grid-template-columns: 1fr; }
  .ec-stats { flex-direction: column; align-items: center; }
}