.chat-shell {
  display: grid;
  grid-template-columns: minmax(200px, 240px) minmax(0, 1fr) minmax(260px, 320px);
  min-height: 0;
  flex: 1;
}

.chat-rail {
  display: flex;
  flex-direction: column;
  gap: 10px;
  min-height: 0;
  padding: 12px;
  border-right: 1px solid var(--st-border);
  background: color-mix(in srgb, var(--st-surface) 88%, var(--st-bg));
}

.chat-path {
  margin: 0;
}

.chat-path .path-bar-list {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: 12px;
  color: var(--st-muted);
}

.chat-path .path-bar-item {
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.chat-path .path-bar-item:not(:last-child)::after {
  content: "›";
  margin-left: 4px;
  color: var(--st-faint);
}

.chat-path button,
.chat-path .path-bar-current {
  border: 0;
  background: transparent;
  color: inherit;
  padding: 0;
  font: inherit;
  cursor: pointer;
}

.chat-path button:hover {
  color: var(--st-accent);
}

.chat-path .path-bar-current {
  color: var(--st-text);
  font-weight: 600;
  cursor: default;
}

.chat-rail-actions {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.chat-rail-list {
  flex: 1;
  min-height: 0;
  overflow: auto;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.chat-rail-item {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 8px;
  width: 100%;
  text-align: left;
  border: 1px solid transparent;
  border-radius: 8px;
  background: transparent;
  color: var(--st-text);
  padding: 8px 10px;
  cursor: pointer;
  font: inherit;
}

.chat-rail-item:hover {
  background: var(--st-accent-soft);
}

.chat-rail-item.active {
  border-color: color-mix(in srgb, var(--st-accent) 45%, var(--st-border));
  background: var(--st-accent-soft);
}

.chat-rail-item-main {
  min-width: 0;
  flex: 1;
}

.chat-rail-item-title {
  display: block;
  font-weight: 600;
  font-size: 13px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.chat-rail-item-meta {
  display: block;
  margin-top: 2px;
  font-size: 11px;
  color: var(--st-muted);
}

.chat-rail-item-del {
  flex-shrink: 0;
  border: 0;
  background: transparent;
  color: var(--st-faint);
  cursor: pointer;
  padding: 2px 4px;
  font-size: 12px;
}

.chat-rail-item-del:hover {
  color: var(--st-danger);
}

.chat-rail-note {
  margin: 0;
  font-size: 11px;
  color: var(--st-faint);
  line-height: 1.4;
}

.chat-main {
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
  background: var(--st-bg);
}

.chat-room {
  display: flex;
  flex-direction: column;
  min-height: 0;
  flex: 1;
}

.chat-room-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--st-border);
  background: var(--st-surface);
}

.chat-room-titles h2 {
  margin: 0;
  font-size: 16px;
  font-weight: 650;
}

.chat-room-sub {
  margin: 4px 0 0;
  font-size: 12px;
  color: var(--st-muted);
}

.chat-room-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-end;
  gap: 6px;
}

.chat-profile-label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--st-muted);
}

.chat-profile-label select {
  min-width: 140px;
  max-width: 220px;
  border: 1px solid var(--st-border-strong);
  border-radius: 6px;
  background: var(--st-surface);
  color: var(--st-text);
  padding: 4px 8px;
  font: inherit;
}

.chat-context {
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
  border-left: 1px solid var(--st-border);
  background: color-mix(in srgb, var(--st-surface) 92%, var(--st-bg));
}

.chat-context-head {
  flex-shrink: 0;
  padding: 12px 14px 8px;
  border-bottom: 1px solid var(--st-border);
}

.chat-context-head h2 {
  margin: 0;
  font-size: 14px;
  font-weight: 650;
}

.chat-context-sub {
  margin: 4px 0 0;
  font-size: 11px;
  color: var(--st-muted);
  line-height: 1.35;
}

.chat-shell-editor {
  display: grid;
  gap: 10px;
  padding: 12px 14px 16px;
  overflow: auto;
  min-height: 0;
  flex: 1;
  align-content: start;
}

.chat-shell-editor label {
  display: grid;
  gap: 4px;
  font-size: 12px;
  color: var(--st-muted);
}

.chat-shell-editor input,
.chat-shell-editor textarea {
  border: 1px solid var(--st-border-strong);
  border-radius: 6px;
  background: var(--st-surface);
  color: var(--st-text);
  padding: 6px 8px;
  font: inherit;
  resize: vertical;
}

.chat-shell-editor input:disabled,
.chat-shell-editor textarea:disabled {
  opacity: 0.65;
  background: color-mix(in srgb, var(--st-bg) 70%, var(--st-surface));
}

.chat-shell-editor-actions {
  display: flex;
  justify-content: flex-end;
  padding-top: 4px;
}

/* —— 模型竞技场：并排整列 chat pane —— */
.chat-arena {
  flex: 1;
  min-height: 0;
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: minmax(280px, 1fr);
  gap: 0;
  overflow-x: auto;
  overflow-y: hidden;
  background: var(--st-bg);
  border-bottom: 1px solid var(--st-border);
}

.chat-arena-empty {
  grid-column: 1 / -1;
  margin: auto;
  padding: 24px 16px;
  text-align: center;
  color: var(--st-muted);
  font-size: 13px;
  line-height: 1.5;
  max-width: 28rem;
}

.chat-arena-col {
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
  border-right: 1px solid var(--st-border);
  background: var(--st-surface);
}

.chat-arena-col:last-child {
  border-right: 0;
}

.chat-arena-col.is-selected {
  background: color-mix(in srgb, var(--st-accent-soft) 55%, var(--st-surface));
}

.chat-arena-col-head {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 8px 12px;
  border-bottom: 1px solid var(--st-border);
  background: color-mix(in srgb, var(--st-bg) 55%, var(--st-surface));
  position: sticky;
  top: 0;
  z-index: 1;
}

.chat-arena-col-titles {
  min-width: 0;
}

.chat-arena-col-name {
  display: block;
  font-size: 13px;
  font-weight: 650;
  color: var(--st-text);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.chat-arena-col-model {
  display: block;
  margin-top: 1px;
  font-size: 11px;
  color: var(--st-muted);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.chat-arena-col-actions {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-shrink: 0;
}

.chat-arena-col-actions .st-btn {
  padding: 4px 8px;
  font-size: 12px;
}

.chat-arena-col-scroll {
  flex: 1;
  min-height: 0;
  overflow: auto;
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.chat-bubble {
  max-width: 100%;
  padding: 8px 10px;
  border-radius: 8px;
  border: 1px solid var(--st-border);
  background: var(--st-bg);
  white-space: pre-wrap;
  word-break: break-word;
  line-height: 1.5;
  font-size: 13px;
}

.chat-bubble.user {
  align-self: stretch;
  background: color-mix(in srgb, var(--st-accent-soft) 70%, var(--st-bg));
  border-color: color-mix(in srgb, var(--st-accent) 28%, var(--st-border));
}

.chat-bubble.assistant {
  align-self: stretch;
  background: var(--st-surface);
}

.chat-bubble.assistant.is-selected {
  border-color: var(--st-accent);
  background: var(--st-accent-soft);
}

.chat-bubble-foot {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 6px;
  margin-top: 6px;
}

.chat-select-btn {
  border: 1px solid var(--st-border-strong);
  border-radius: 6px;
  background: var(--st-surface);
  color: var(--st-text);
  font: inherit;
  font-size: 12px;
  font-weight: 500;
  padding: 4px 8px;
  cursor: pointer;
}

.chat-select-btn:hover {
  border-color: var(--st-accent);
  background: var(--st-accent-soft);
}

.chat-select-btn.is-on {
  border-color: var(--st-accent);
  background: var(--st-accent-soft);
  color: var(--st-text);
  font-weight: 650;
}

.chat-arena-col-empty {
  margin: auto;
  padding: 16px 8px;
  text-align: center;
  color: var(--st-faint);
  font-size: 12px;
  line-height: 1.4;
}

.chat-bubble-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 6px;
  font-size: 11px;
  color: var(--st-muted);
}

.chat-bubble-actions {
  display: flex;
  gap: 4px;
}

.chat-bubble-actions button {
  border: 0;
  background: transparent;
  color: var(--st-muted);
  cursor: pointer;
  font: inherit;
  font-size: 11px;
  padding: 0 4px;
}

.chat-bubble-actions button:hover {
  color: var(--st-accent);
}

.chat-bubble-thinking {
  margin: 0 0 8px;
  padding: 8px;
  border-radius: 6px;
  background: color-mix(in srgb, var(--st-bg) 80%, transparent);
  color: var(--st-muted);
  font-size: 12px;
  white-space: pre-wrap;
}

.chat-composer {
  padding: 10px 16px 14px;
  border-top: 1px solid var(--st-border);
  background: var(--st-surface);
  display: grid;
  gap: 6px;
}

.chat-input-shell {
  position: relative;
  display: flex;
  align-items: flex-end;
  gap: 8px;
  min-height: 36px;
  border: 1px solid var(--st-border-strong);
  border-radius: 10px;
  padding: 4px 6px 4px 10px;
  background: var(--st-bg);
  transition: border-color 0.12s ease, box-shadow 0.12s ease;
}

.chat-input-shell:focus-within {
  border-color: var(--st-accent);
  box-shadow: 0 0 0 2px var(--st-accent-soft);
}

.chat-input-shell textarea {
  flex: 1 1 auto;
  min-width: 0;
  min-height: 28px;
  max-height: min(42vh, 280px);
  border: 0;
  border-radius: 0;
  background: transparent;
  color: var(--st-text);
  padding: 6px 4px;
  margin: 0;
  font: inherit;
  line-height: 1.5;
  resize: none;
  field-sizing: content;
}

.chat-input-shell textarea:focus {
  outline: none;
}

.chat-shell-actions {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 6px;
  padding-bottom: 0;
}

.chat-btn-icon {
  box-sizing: border-box;
  width: 28px;
  min-width: 28px;
  height: 28px;
  padding: 0;
  border: 1px solid var(--st-border-strong);
  border-radius: 8px;
  background: var(--st-surface);
  color: var(--st-text);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.chat-btn-icon:hover:not(:disabled) {
  border-color: var(--st-accent);
  background: var(--st-accent-soft);
}

.chat-btn-icon:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

.chat-btn-icon-primary {
  background: var(--st-accent);
  border-color: var(--st-accent);
  color: #fff;
}

.chat-btn-icon-primary:hover:not(:disabled) {
  filter: brightness(0.96);
  background: var(--st-accent);
  border-color: var(--st-accent);
}

.chat-send-icon {
  display: block;
}

.chat-status {
  margin: 0;
  font-size: 12px;
  color: var(--st-muted);
}

.chat-status.error {
  color: var(--st-danger);
}

.st-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  border: 1px solid var(--st-border-strong);
  border-radius: 7px;
  background: var(--st-surface);
  color: var(--st-text);
  padding: 6px 10px;
  font: inherit;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
}

.st-btn:hover {
  border-color: var(--st-accent);
  background: var(--st-accent-soft);
}

.st-btn:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

.st-btn-primary {
  border-color: color-mix(in srgb, var(--st-accent) 55%, var(--st-border-strong));
  background: var(--st-accent-soft);
  color: var(--st-text);
  font-weight: 600;
}

.chat-dialog {
  border: 1px solid var(--st-border-strong);
  border-radius: 12px;
  padding: 0;
  background: var(--st-surface);
  color: var(--st-text);
  max-width: min(420px, 92vw);
}

.chat-dialog-wide {
  max-width: min(720px, 94vw);
  width: 94vw;
}

.chat-dialog::backdrop {
  background: rgba(0, 0, 0, 0.35);
}

.chat-dialog form,
.chat-dialog > div {
  display: grid;
  gap: 10px;
  padding: 16px;
}

.chat-dialog h3 {
  margin: 0;
  font-size: 16px;
}

.chat-dialog-hint {
  margin: 0;
  font-size: 12px;
  color: var(--st-muted);
}

.chat-dialog label {
  display: grid;
  gap: 4px;
  font-size: 12px;
  color: var(--st-muted);
}

.chat-dialog input {
  border: 1px solid var(--st-border-strong);
  border-radius: 6px;
  background: var(--st-bg);
  color: var(--st-text);
  padding: 6px 8px;
  font: inherit;
}

.chat-dialog-actions {
  display: flex;
  justify-content: flex-end;
  gap: 8px;
}

.chat-compare-list {
  display: grid;
  gap: 6px;
  max-height: 240px;
  overflow: auto;
}

.chat-compare-list label {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--st-text);
  font-size: 13px;
}

.chat-compare-result-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--st-border);
}

.chat-compare-result-body {
  display: grid;
  gap: 12px;
  padding: 16px;
  max-height: 70vh;
  overflow: auto;
}

.chat-compare-card {
  border: 1px solid var(--st-border);
  border-radius: 8px;
  padding: 10px 12px;
  background: var(--st-bg);
}

.chat-compare-card h4 {
  margin: 0 0 6px;
  font-size: 13px;
}

.chat-compare-card pre {
  margin: 0 0 8px;
  white-space: pre-wrap;
  word-break: break-word;
  font: inherit;
  font-size: 13px;
}

@media (max-width: 1100px) {
  .chat-shell {
    grid-template-columns: minmax(180px, 220px) minmax(0, 1fr) minmax(220px, 280px);
  }
}

@media (max-width: 860px) {
  .chat-shell {
    grid-template-columns: 1fr;
    grid-template-rows: auto minmax(0, 1fr) auto;
    overflow: auto;
  }

  .chat-rail {
    border-right: 0;
    border-bottom: 1px solid var(--st-border);
    max-height: 28vh;
  }

  .chat-context {
    border-left: 0;
    border-top: 1px solid var(--st-border);
    max-height: 36vh;
  }

  .chat-main {
    min-height: 42vh;
  }
}