/* css/layout.css — masthead, tab nav, panel grid */

.masthead {
  border-bottom: 3px double var(--rule);
  background: linear-gradient(180deg, var(--paper) 0%, rgba(245,241,232,0.85) 100%);
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(8px);
}
.mast-inner {
  max-width: 1400px;
  margin: 0 auto;
  padding: 18px 32px 0;
  display: flex;
  flex-direction: column;
  gap: 18px;
}
.mast-brand { display: flex; align-items: center; gap: 16px; }
.mast-mark {
  width: 52px; height: 52px;
  background: var(--rule);
  color: var(--paper);
  display: grid; place-items: center;
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.mast-title { font-size: 26px; line-height: 1.1; }
.mast-sub {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
  margin-top: 4px;
}

.mast-tabs:not(.formatter-nav) {
  display: flex;
  gap: 4px;
  overflow-x: auto;
  margin: 0 -32px;
  padding: 0 32px;
}
.tab-btn:not(.formatter-nav-btn) {
  padding: 12px 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  border-bottom: 2px solid transparent;
  white-space: nowrap;
  transition: color 0.15s, border-color 0.15s;
}
.tab-btn:not(.formatter-nav-btn):hover { color: var(--ink); }
.tab-btn:not(.formatter-nav-btn).active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.workspace {
  max-width: 1400px;
  margin: 0 auto;
  padding: 32px;
}

.tab-panel { display: none; animation: fadeIn 0.2s ease; }
.tab-panel.active { display: block; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

.panel-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}
.card-wide { grid-column: 1 / -1; }

@media (max-width: 900px) {
  .panel-grid { grid-template-columns: 1fr; }
  .workspace { padding: 20px 16px; }
  .mast-inner { padding: 16px 16px 0; }
}