/*!
 * NFN Button — headless component primitive.
 *
 * Theme adapts via [data-theme] on a parent. Requires NFN tokens
 * (build/css/tokens.<theme>.css) to be loaded somewhere upstream.
 *
 *   <button class="nfn-btn">Default</button>
 *   <button class="nfn-btn nfn-btn--primary">Primary</button>
 *   <button class="nfn-btn nfn-btn--ghost nfn-btn--sm">Cancel</button>
 *   <button class="nfn-btn nfn-btn--danger">Delete</button>
 *   <button class="nfn-btn" aria-busy="true">Running…</button>
 *   <a href="..." class="nfn-btn nfn-btn--primary">Link as button</a>
 *
 * Variants: --primary | --secondary (alias of base) | --ghost | --danger
 * Sizes:    --sm | --md (default) | --lg
 * Modifiers: --icon-only | --block
 * States:   :hover :active :focus-visible [disabled] [aria-busy="true"]
 */

.nfn-btn {
  --btn-pad-y: var(--nfn-space-control-pad-y-md);
  --btn-pad-x: var(--nfn-space-control-pad-x-md);
  --btn-gap: var(--nfn-space-inline-sm);
  --btn-font-size: var(--nfn-text-label-font-size);
  --btn-font-weight: var(--nfn-text-label-font-weight);
  --btn-radius: var(--nfn-radius-control-md);
  --btn-bg: var(--nfn-color-bg-surface);
  --btn-bg-hover: var(--nfn-color-bg-hover);
  --btn-bg-active: var(--nfn-color-bg-active);
  --btn-fg: var(--nfn-color-text-primary);
  --btn-border: var(--nfn-color-border-default);
  --btn-border-hover: var(--nfn-color-border-strong);
  --btn-ring: var(--nfn-color-interactive-focus-ring);

  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--btn-gap);
  padding: var(--btn-pad-y) var(--btn-pad-x);
  margin: 0;
  border: 1px solid var(--btn-border);
  border-radius: var(--btn-radius);
  background: var(--btn-bg);
  color: var(--btn-fg);
  font-family: var(--nfn-text-label-font-family);
  font-size: var(--btn-font-size);
  font-weight: var(--btn-font-weight);
  line-height: 1;
  letter-spacing: var(--nfn-text-label-letter-spacing);
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
  user-select: none;
  appearance: none;
  -webkit-appearance: none;
  transition:
    background var(--nfn-motion-duration-micro) var(--nfn-motion-easing-standard),
    border-color var(--nfn-motion-duration-micro) var(--nfn-motion-easing-standard),
    color var(--nfn-motion-duration-micro) var(--nfn-motion-easing-standard),
    outline-color var(--nfn-motion-duration-micro) var(--nfn-motion-easing-standard);
}

.nfn-btn:hover {
  background: var(--btn-bg-hover);
  border-color: var(--btn-border-hover);
}

.nfn-btn:active {
  background: var(--btn-bg-active);
}

.nfn-btn:focus-visible {
  outline: 2px solid var(--btn-ring);
  outline-offset: 2px;
}

.nfn-btn[disabled],
.nfn-btn[aria-disabled="true"] {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

.nfn-btn[aria-busy="true"] {
  pointer-events: none;
  cursor: wait;
}

.nfn-btn[aria-busy="true"]::before {
  content: "";
  width: 1em;
  height: 1em;
  border: 2px solid currentColor;
  border-right-color: transparent;
  border-radius: 50%;
  animation: nfn-btn-spin var(--nfn-duration-slower) linear infinite;
}

@keyframes nfn-btn-spin {
  to { transform: rotate(360deg); }
}

.nfn-btn--primary {
  --btn-bg: var(--nfn-color-accent-default);
  --btn-bg-hover: var(--nfn-color-accent-hover);
  --btn-bg-active: var(--nfn-color-accent-active);
  --btn-fg: var(--nfn-color-text-on-accent);
  --btn-border: var(--nfn-color-accent-default);
  --btn-border-hover: var(--nfn-color-accent-hover);
}

.nfn-btn--ghost {
  --btn-bg: transparent;
  --btn-bg-hover: var(--nfn-color-bg-hover);
  --btn-bg-active: var(--nfn-color-bg-active);
  --btn-border: transparent;
  --btn-border-hover: transparent;
}

.nfn-btn--danger {
  --btn-bg: var(--nfn-color-status-error);
  --btn-bg-hover: var(--nfn-color-status-error);
  --btn-bg-active: var(--nfn-color-status-error);
  --btn-fg: var(--nfn-color-text-on-accent);
  --btn-border: var(--nfn-color-status-error);
  --btn-border-hover: var(--nfn-color-status-error);
  --btn-ring: var(--nfn-color-status-error);
}
.nfn-btn--danger:hover  { filter: brightness(1.1); }
.nfn-btn--danger:active { filter: brightness(0.9); }

.nfn-btn--sm {
  --btn-pad-y: var(--nfn-space-control-pad-y-sm);
  --btn-pad-x: var(--nfn-space-control-pad-x-sm);
  --btn-font-size: var(--nfn-font-size-xs);
  --btn-radius: var(--nfn-radius-control-sm);
  --btn-gap: var(--nfn-space-1);
}

.nfn-btn--lg {
  --btn-pad-y: var(--nfn-space-control-pad-y-lg);
  --btn-pad-x: var(--nfn-space-control-pad-x-lg);
  --btn-font-size: var(--nfn-font-size-base);
  --btn-radius: var(--nfn-radius-control-md);
}

.nfn-btn--icon-only {
  --btn-pad-x: var(--btn-pad-y);
  aspect-ratio: 1;
}

.nfn-btn--block {
  display: flex;
  width: 100%;
}

@media (prefers-reduced-motion: reduce) {
  .nfn-btn { transition: none; }
  .nfn-btn[aria-busy="true"]::before { animation-duration: 2s; }
}
/*!
 * NFN Card — headless component primitive.
 *
 * Composes the surface-os semantic surfaces (panel / agent-card / log-row /
 * flow-trace), agent-state via [data-agent-state], and density-aware padding
 * via an ancestor [data-density]. Theme adapts via [data-theme] on a parent.
 * Requires NFN tokens (build/css/tokens.<theme>.css) loaded upstream.
 *
 *   <article class="nfn-card">
 *     <header class="nfn-card__header">
 *       <h3 class="nfn-card__title">Title</h3>
 *       <p class="nfn-card__meta">Meta</p>
 *     </header>
 *     <div class="nfn-card__body">Body</div>
 *     <footer class="nfn-card__footer">…</footer>
 *   </article>
 *
 *   <article class="nfn-card nfn-card--agent" data-agent-state="running">…</article>
 *   <article class="nfn-card nfn-card--log">…</article>
 *   <article class="nfn-card nfn-card--flow" data-agent-state="awaiting-human">…</article>
 *
 * Variants: --agent | --log | --flow (default = panel)
 * State:    [data-agent-state="idle|running|blocked|awaiting-human|errored|complete"]
 * Density:  ancestor [data-density="dashboard|reading"]
 * Slots:    __header __title __meta __body __footer __state
 */

.nfn-card {
  --card-bg: var(--nfn-surface-panel-bg);
  --card-border: var(--nfn-surface-panel-border);
  --card-radius: var(--nfn-surface-panel-radius);
  --card-inset: var(--nfn-surface-panel-inset);
  --card-stack: var(--nfn-surface-panel-stack);
  --card-rail: transparent;
  --card-rail-width: 0;

  display: flex;
  flex-direction: column;
  gap: var(--card-stack);
  padding: var(--card-inset);
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-left: calc(1px + var(--card-rail-width)) solid var(--card-rail, var(--card-border));
  border-radius: var(--card-radius);
  color: var(--nfn-color-text-primary);
  box-sizing: border-box;
  transition:
    background var(--nfn-motion-duration-micro) var(--nfn-motion-easing-standard),
    border-color var(--nfn-motion-duration-micro) var(--nfn-motion-easing-standard);
}

/* Variant: agent-card — elevated surface, tighter rhythm */
.nfn-card--agent {
  --card-bg: var(--nfn-surface-agent-card-bg);
  --card-border: var(--nfn-surface-agent-card-border);
  --card-radius: var(--nfn-surface-agent-card-radius);
  --card-inset: var(--nfn-surface-agent-card-inset);
  --card-stack: var(--nfn-surface-agent-card-stack);
}

/* Variant: log-row — single row, hoverable */
.nfn-card--log {
  --card-bg: var(--nfn-surface-log-row-bg);
  --card-border: var(--nfn-surface-log-row-border);
  --card-radius: var(--nfn-surface-log-row-radius);
  --card-inset: var(--nfn-surface-log-row-inset);
  --card-stack: var(--nfn-surface-log-row-inline);
  flex-direction: row;
  align-items: center;
  gap: var(--nfn-surface-log-row-inline);
}
.nfn-card--log:hover {
  --card-bg: var(--nfn-surface-log-row-bg-hover);
}

/* Variant: flow-trace — canvas surface, left rail */
.nfn-card--flow {
  --card-bg: var(--nfn-surface-flow-trace-bg);
  --card-border: var(--nfn-surface-flow-trace-border);
  --card-radius: var(--nfn-surface-flow-trace-radius);
  --card-inset: var(--nfn-surface-flow-trace-inset);
  --card-stack: var(--nfn-surface-flow-trace-stack);
  --card-rail: var(--nfn-surface-flow-trace-rail);
  --card-rail-width: 2px;
}
.nfn-card--flow[data-agent-state] {
  --card-rail: var(--nfn-surface-flow-trace-rail-active);
}

/* Agent state — tints rail + adds a state-coloured top accent */
.nfn-card[data-agent-state="running"] { --card-rail: var(--nfn-agent-running-border); --card-rail-width: 2px; }
.nfn-card[data-agent-state="blocked"] { --card-rail: var(--nfn-agent-blocked-border); --card-rail-width: 2px; }
.nfn-card[data-agent-state="awaiting-human"] { --card-rail: var(--nfn-agent-awaiting-human-border); --card-rail-width: 2px; }
.nfn-card[data-agent-state="errored"] { --card-rail: var(--nfn-agent-errored-border); --card-rail-width: 2px; }
.nfn-card[data-agent-state="complete"] { --card-rail: var(--nfn-agent-complete-border); --card-rail-width: 2px; }
.nfn-card[data-agent-state="idle"]    { --card-rail: var(--nfn-agent-idle-border);    --card-rail-width: 2px; }

/* Slots */
.nfn-card__header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--nfn-space-inline-md);
  margin: 0;
}

.nfn-card__title {
  margin: 0;
  font-family: var(--nfn-text-heading-3-font-family);
  font-size: var(--nfn-text-heading-3-font-size);
  font-weight: var(--nfn-text-heading-3-font-weight);
  line-height: var(--nfn-text-heading-3-line-height);
  letter-spacing: var(--nfn-text-heading-3-letter-spacing);
  color: var(--nfn-color-text-heading);
}

.nfn-card__meta {
  margin: 0;
  font-family: var(--nfn-text-caption-font-family);
  font-size: var(--nfn-text-caption-font-size);
  font-weight: var(--nfn-text-caption-font-weight);
  line-height: var(--nfn-text-caption-line-height);
  letter-spacing: var(--nfn-text-caption-letter-spacing);
  color: var(--nfn-color-text-muted);
  text-transform: uppercase;
  white-space: nowrap;
}

.nfn-card__body {
  margin: 0;
  font-family: var(--nfn-text-body-default-font-family);
  font-size: var(--nfn-text-body-default-font-size);
  font-weight: var(--nfn-text-body-default-font-weight);
  line-height: var(--nfn-text-body-default-line-height);
  color: var(--nfn-color-text-secondary);
}

.nfn-card__footer {
  display: flex;
  align-items: center;
  gap: var(--nfn-space-inline-sm);
  margin: 0;
}

/* Agent-state badge — drop-in slot, picks colour from data-state */
.nfn-card__state {
  display: inline-flex;
  align-items: center;
  gap: var(--nfn-space-inline-xs);
  padding: var(--nfn-space-1) var(--nfn-space-2);
  border: 1px solid var(--state-border, var(--nfn-agent-idle-border));
  border-radius: var(--nfn-radius-pill);
  background: var(--state-bg, var(--nfn-agent-idle-bg));
  color: var(--state-fg, var(--nfn-agent-idle-fg));
  font-family: var(--nfn-text-label-font-family);
  font-size: var(--nfn-font-size-xs);
  font-weight: var(--nfn-text-label-font-weight);
  line-height: 1;
  letter-spacing: var(--nfn-text-label-letter-spacing);
  white-space: nowrap;
}
.nfn-card__state::before {
  content: "";
  width: 0.5em;
  height: 0.5em;
  border-radius: 50%;
  background: var(--state-dot, var(--nfn-agent-idle-dot));
}
.nfn-card__state[data-state="idle"]    { --state-bg: var(--nfn-agent-idle-bg); --state-fg: var(--nfn-agent-idle-fg); --state-border: var(--nfn-agent-idle-border); --state-dot: var(--nfn-agent-idle-dot); }
.nfn-card__state[data-state="running"] { --state-bg: var(--nfn-agent-running-bg); --state-fg: var(--nfn-agent-running-fg); --state-border: var(--nfn-agent-running-border); --state-dot: var(--nfn-agent-running-dot); }
.nfn-card__state[data-state="blocked"] { --state-bg: var(--nfn-agent-blocked-bg); --state-fg: var(--nfn-agent-blocked-fg); --state-border: var(--nfn-agent-blocked-border); --state-dot: var(--nfn-agent-blocked-dot); }
.nfn-card__state[data-state="awaiting-human"] { --state-bg: var(--nfn-agent-awaiting-human-bg); --state-fg: var(--nfn-agent-awaiting-human-fg); --state-border: var(--nfn-agent-awaiting-human-border); --state-dot: var(--nfn-agent-awaiting-human-dot); }
.nfn-card__state[data-state="errored"] { --state-bg: var(--nfn-agent-errored-bg); --state-fg: var(--nfn-agent-errored-fg); --state-border: var(--nfn-agent-errored-border); --state-dot: var(--nfn-agent-errored-dot); }
.nfn-card__state[data-state="complete"] { --state-bg: var(--nfn-agent-complete-bg); --state-fg: var(--nfn-agent-complete-fg); --state-border: var(--nfn-agent-complete-border); --state-dot: var(--nfn-agent-complete-dot); }
.nfn-card__state[data-state="running"]::before { animation: nfn-card-pulse calc(var(--nfn-duration-slower) * 3) ease-in-out infinite; }

@keyframes nfn-card-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

/* Density — ancestor [data-density] retunes the rhythm */
[data-density="dashboard"] .nfn-card {
  --card-inset: var(--nfn-density-dashboard-inset);
  --card-stack: var(--nfn-density-dashboard-stack);
  font-size: var(--nfn-density-dashboard-font-size);
  line-height: var(--nfn-density-dashboard-line-height);
}
[data-density="reading"] .nfn-card {
  --card-inset: var(--nfn-density-reading-inset);
  --card-stack: var(--nfn-density-reading-stack);
  font-size: var(--nfn-density-reading-font-size);
  line-height: var(--nfn-density-reading-line-height);
}

@media (prefers-reduced-motion: reduce) {
  .nfn-card { transition: none; }
  .nfn-card__state[data-state="running"]::before { animation: none; }
}