/* Page frame: header, viewport + sidebar, footer. */

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

html, body { height: 100%; }

body {
  margin: 0;
  font-family: var(--font);
  font-size: 14px;
  line-height: 1.5;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* ---------------------------------------------------------------- header */

.app-header {
  flex: 0 0 auto;
  height: var(--header-h);
  display: flex;
  align-items: center;
  gap: var(--space-4);
  padding: 0 var(--space-4);
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  position: relative;
  z-index: 20;
}

.brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-width: 0;
}

/* The logo carries its own navy plate, so it needs a hairline in dark mode
   to stay distinct from the header behind it. */
.brand__logo {
  height: 26px;
  width: auto;
  display: block;
  border-radius: 5px;
}

:root[data-theme="dark"] .brand__logo,
:root:not([data-theme="light"]) .brand__logo { outline: 1px solid var(--border); }

@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) .brand__logo { outline: none; }
}

.brand__tool {
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--text-dim);
  white-space: nowrap;
}

.brand__sep {
  width: 1px;
  height: 22px;
  background: var(--border);
}

.header-actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* ------------------------------------------------------------------ main */

.app-main {
  flex: 1 1 auto;
  display: grid;
  grid-template-columns: minmax(0, 1fr) var(--sidebar-w);
  min-height: 0;
}

.viewport {
  display: flex;
  flex-direction: column;
  min-width: 0;
  padding: var(--space-4);
  gap: var(--space-4);
  overflow-y: auto;
}

/*
 * Flex items shrink by default, so in a short window the browser was
 * compressing the tab bar and the diagram rather than letting the column
 * scroll. Nothing here may shrink: the stage grows into spare room, and
 * everything else keeps the height its content needs.
 */
.viewport > * { flex: 0 0 auto; }

.viewport__stage {
  flex: 1 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 240px;
  padding: var(--space-5) var(--space-4);
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  overflow-x: auto;
}

.viewport__stage > * {
  width: 100%;
  max-width: 780px;
}

.viewport__stage svg {
  width: 100%;
  height: auto;
  display: block;
  margin: 0 auto;
}

/* The palette strip that appears when a band is selected. */
.palette {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-2);
  margin-top: var(--space-4);
  padding-top: var(--space-4);
  border-top: 1px dashed var(--border);
}

.palette__label {
  flex: 1 0 100%;
  text-align: center;
  font-size: 12px;
  color: var(--text-dim);
  margin-bottom: var(--space-1);
}

.palette__swatch {
  width: 38px;
  height: 38px;
  padding: 0;
  border: 2px solid var(--border-strong);
  border-radius: var(--radius);
  cursor: pointer;
  position: relative;
}

.palette__swatch:hover { transform: scale(1.08); }
.palette__swatch[aria-pressed="true"] { border-color: var(--accent-strong); box-shadow: 0 0 0 3px var(--accent-soft); }
.palette__swatch span { font-size: 9px; font-weight: 700; }

.sidebar {
  border-left: 1px solid var(--border);
  background: var(--panel);
  overflow-y: auto;
  display: flex;
  flex-direction: column;
}

.sidebar__scroll { flex: 1 1 auto; }

/* ---------------------------------------------------------------- footer */

.app-footer {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  gap: var(--space-4);
  flex-wrap: wrap;
  padding: var(--space-3) var(--space-4);
  background: var(--panel);
  border-top: 1px solid var(--border);
  font-size: 12px;
  color: var(--text-faint);
}

.app-footer nav {
  margin-left: auto;
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
}

/* Long/short label pairs, swapped by the responsive rules below. */
.btn-label--short { display: none; }

/* ------------------------------------------------------------ responsive */

@media (max-width: 1040px) {
  .app-main {
    grid-template-columns: minmax(0, 1fr);
  }

  .sidebar {
    border-left: none;
    border-top: 1px solid var(--border);
  }

  .viewport { overflow-y: visible; }
  .sidebar { overflow-y: visible; }
  body { height: auto; }
}

@media (max-width: 700px) {
  /* The full labels cannot fit beside the logo, so shorten them. */
  .btn-label--long { display: none; }
  .btn-label--short { display: inline; }
}

@media (max-width: 560px) {
  .brand__tool, .brand__sep { display: none; }
  .viewport { padding: var(--space-3); }

  /* Give every part of the header permission to shrink, and let the logo be
     the first thing to give way - it is decorative next to the controls. */
  .app-header {
    gap: var(--space-2);
    padding: 0 var(--space-3);
  }

  .brand { flex: 0 1 auto; min-width: 0; overflow: hidden; }

  /* The logo sits inside an anchor, so the anchor is the flex item - it has to
     carry the shrink rules or the image keeps its full intrinsic width and
     shoves the action buttons over the wordmark. */
  .brand__home { flex: 0 1 auto; min-width: 0; overflow: hidden; }

  .brand__logo {
    height: 22px;
    max-width: 100%;
    flex: 0 1 auto;
    min-width: 0;
    object-fit: contain;
    object-position: left center;
  }

  .header-actions { flex: 0 0 auto; gap: var(--space-1); }
  .header-actions .btn { padding: 6px 8px; }
}