/* Button component. Canonical markup: class="btn btn--<variant>".
   Each variant reproduces one pre-token family exactly; the old class stays in
   each selector as an alias, so theme rules still in legacy keep matching it.
   Merging variants that only differ by a shadow is a visual decision for the
   theme migration (phase 4), not for this file.
   - btn--secondary (cloud-button), btn--primary (cloud-button primary)
   - btn--icon (btn-header), btn--icon-danger
   - btn--tool (btn-action), btn--send (btn-send), btn--mini (btn-create-group)
   - btn--float (btn-scroll-bottom), btn--cta (btn-enter)
   - btn--dialog (btn-modal-secondary), btn--dialog-primary, btn--danger
   Variants without an alias have no pre-token class left in the cloud markup. */
@layer components {
  .btn { cursor: pointer; }

  /* Secondary and primary: default actions in panels and dialogs. */
  .btn--secondary, .btn--primary, .cloud-button {
    display: inline-flex; align-items: center; justify-content: center; gap: 8px;
    padding: 10px 14px;
    border: 1px solid var(--sys-border);
    border-radius: var(--sys-radius-sm);
    background: var(--sys-surface-control);
    color: var(--sys-on-surface);
    cursor: pointer;
    text-decoration: none;
    box-shadow: var(--sys-elevation-1);
  }
  .btn--secondary:hover, .btn--primary:hover, .cloud-button:hover { background: var(--sys-surface-hover); }
  .btn--primary, .btn--primary:hover, .cloud-button.primary {
    background: var(--sys-accent-gradient);
    color: var(--comp-button-on-accent);
    border-color: var(--sys-border-strong);
  }

  /* Icon: header actions, transparent until hovered. */
  .btn--icon, .btn-header {
    display: flex; align-items: center; justify-content: center;
    width: 40px; height: 40px;
    border: 1px solid transparent;
    border-radius: var(--sys-radius-md);
    color: var(--sys-on-surface-variant);
    cursor: pointer;
    transition: all var(--sys-motion-fast) ease;
  }
  .btn--icon:hover, .btn-header:hover {
    background: var(--sys-surface-control);
    border-color: var(--sys-border);
    box-shadow: var(--sys-elevation-1);
    color: var(--sys-on-surface);
  }
  .btn--icon-danger:hover {
    background: var(--comp-button-danger-soft-bg);
    border-color: var(--comp-button-danger-soft-border);
    color: var(--sys-status-danger);
  }

  /* Mini: compact square next to a section title. */
  .btn--mini, .btn-create-group {
    display: flex; align-items: center; justify-content: center;
    width: 26px; height: 26px;
    color: var(--sys-on-surface-variant);
    background: var(--sys-surface-control);
    border: 1px solid var(--sys-border);
    box-shadow: var(--comp-button-mini-shadow);
    border-radius: var(--sys-radius-sm);
    cursor: pointer;
    font-size: 18px;
    line-height: 1;
    transition: all var(--sys-motion-fast) ease;
  }
  .btn--mini:hover, .btn-create-group:hover {
    color: var(--comp-button-on-accent);
    background: var(--sys-accent-gradient);
    border-color: var(--comp-button-mini-hover-border);
    box-shadow: var(--comp-button-mini-hover-shadow);
  }

  /* Float: round button over the message list. */
  .btn--float, .btn-scroll-bottom {
    position: absolute;
    bottom: 14px;
    right: 24px;
    width: 42px;
    height: 42px;
    border-radius: var(--sys-radius-full);
    background: var(--sys-surface-plate);
    backdrop-filter: blur(16px) saturate(180%);
    -webkit-backdrop-filter: blur(16px) saturate(180%);
    border: 1px solid var(--sys-border-strong);
    color: var(--sys-on-surface);
    cursor: pointer;
    display: flex; align-items: center; justify-content: center;
    transition: all var(--sys-motion-fast) var(--sys-ease-spring);
    z-index: 10;
    box-shadow: var(--sys-elevation-2);
  }
  @supports (backdrop-filter: url(#liquid-refraction)) {
    .btn--float, .btn-scroll-bottom { backdrop-filter: var(--sys-refraction); }
  }
  .btn--float:hover, .btn-scroll-bottom:hover {
    background: var(--sys-accent-gradient);
    color: var(--comp-button-on-accent);
    border-color: var(--comp-button-float-hover-border);
    transform: translateY(-2px) scale(1.05);
  }

  /* Tool: composer actions (attach, emoji, poll, record). */
  .btn--tool, .btn-action {
    display: flex; align-items: center; justify-content: center;
    width: 42px; height: 42px;
    border: 1px solid transparent;
    border-radius: var(--sys-radius-md);
    color: var(--sys-on-surface-variant);
    cursor: pointer;
    transition: all var(--sys-motion-fast) ease;
    flex-shrink: 0;
  }
  .btn--tool:hover, .btn-action:hover {
    background: var(--sys-surface-control);
    border-color: var(--sys-border);
    box-shadow: var(--sys-elevation-1);
    color: var(--sys-on-surface);
  }
  .btn--tool:active, .btn-action:active { transform: scale(0.92); }

  /* Send: the composer's main action. */
  .btn--send, .btn-send {
    display: flex; align-items: center; justify-content: center;
    width: 42px; height: 42px;
    background: var(--sys-accent-gradient);
    border: 1px solid var(--comp-button-accent-border);
    box-shadow: var(--comp-button-send-shadow);
    border-radius: var(--sys-radius-md);
    color: var(--comp-button-on-accent);
    cursor: pointer;
    transition: all var(--sys-motion-fast) ease;
    flex-shrink: 0;
  }
  .btn--send:hover, .btn-send:hover { transform: scale(1.05); box-shadow: var(--comp-button-send-hover-shadow); }
  .btn--send:active, .btn-send:active { transform: scale(0.95); }

  /* Call to action: full-width login and account buttons. */
  .btn--cta, .btn-enter {
    width: 100%;
    display: flex; align-items: center; justify-content: center; gap: 10px;
    padding: 16px;
    background: var(--sys-accent-gradient);
    border: 1px solid var(--comp-button-accent-border);
    border-radius: var(--sys-radius-md);
    box-shadow: var(--comp-button-cta-shadow);
    font-size: 15px;
    font-weight: 600;
    color: var(--comp-button-on-accent);
    cursor: pointer;
    transition: all var(--sys-motion-normal) ease;
    position: relative;
    overflow: hidden;
  }
  .btn--cta::before, .btn-enter::before {
    content: '';
    position: absolute;
    inset: 0;
    background: var(--sys-accent-gradient-hover);
    opacity: 0;
    transition: opacity var(--sys-motion-normal) ease;
  }
  .btn--cta:hover::before, .btn-enter:hover::before { opacity: 1; }
  .btn--cta:hover, .btn-enter:hover { transform: translateY(-1px); box-shadow: var(--comp-button-cta-hover-shadow); }
  .btn--cta:active, .btn-enter:active { transform: translateY(0); }
  .btn--cta span, .btn--cta svg, .btn-enter span, .btn-enter svg { position: relative; z-index: 1; }

  /* Dialog actions: secondary, primary and destructive. */
  .btn--dialog, .btn--dialog-primary, .btn-modal-secondary {
    padding: 10px 16px;
    border-radius: var(--sys-radius-sm);
    cursor: pointer;
    font-weight: 600;
    transition: all var(--sys-motion-fast) ease;
  }
  .btn--dialog, .btn-modal-secondary {
    color: var(--sys-on-surface-variant);
    background: var(--sys-surface-control);
    border: 1px solid var(--sys-border);
    box-shadow: var(--comp-button-dialog-shadow);
  }
  .btn--dialog:hover, .btn-modal-secondary:hover { color: var(--sys-on-surface); background: var(--sys-surface-hover); }
  .btn--dialog-primary {
    color: var(--comp-button-on-accent);
    background: var(--sys-accent-gradient);
    border: 1px solid var(--comp-button-accent-border);
    box-shadow: var(--comp-button-dialog-primary-shadow);
  }
  .btn--dialog-primary:hover { transform: translateY(-1px); box-shadow: var(--comp-button-dialog-primary-hover-shadow); }
  .btn--danger {
    margin-right: auto;
    padding: 10px 14px;
    border-radius: var(--sys-radius-sm);
    color: var(--comp-button-danger-fg);
    background: var(--comp-button-danger-bg);
    border: 1px solid var(--comp-button-danger-border);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--sys-motion-fast) ease;
  }
  .btn--danger:hover {
    color: var(--comp-button-danger-hover-fg);
    background: var(--comp-button-danger-hover-bg);
    border-color: var(--comp-button-danger-hover-border);
  }
}