:root {
  --bg: #f7f7f5;
  --panel: #ffffff;
  --text: #1f2328;
  --text-muted: #6b7280;
  --border: #e5e7eb;
  --accent: #2563eb;
  --accent-shadow: rgba(37, 99, 235, 0.12);
  --code-bg: #f0f0f0;
  --placeholder: #b5b9c2;
  --tag-bg: #eef4ff;
  --tag-border: #c7dbff;
  --tag-text: #1d4ed8;
  --tag-hover-bg: #e0ebff;
  --tag-hover-border: #a9c4ff;
  --tag-error-bg: #fdecec;
  --tag-error-border: #f5b5b5;
  --tag-error-text: #c0392b;
  --status-ok: #22c55e;
  --status-warn: #f59e0b;
  --editor-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
}

/* 暗色模式：data-theme="dark" 时覆盖变量 */
[data-theme="dark"] {
  --bg: #1a1b1e;
  --panel: #25262b;
  --text: #e4e6eb;
  --text-muted: #9ca3af;
  --border: #3a3b42;
  --accent: #4a8dff;
  --accent-shadow: rgba(74, 141, 255, 0.2);
  --code-bg: #2a2b30;
  --placeholder: #56575c;
  --tag-bg: #1e2a4a;
  --tag-border: #3b5bb5;
  --tag-text: #8db4ff;
  --tag-hover-bg: #243a6e;
  --tag-hover-border: #4a7ad9;
  --tag-error-bg: #3d1f24;
  --tag-error-border: #7a3036;
  --tag-error-text: #ff8585;
  --status-ok: #4ade80;
  --status-warn: #fbbf24;
  --editor-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
  font-size: 15px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.app {
  max-width: 880px;
  margin: 0 auto;
  padding: 32px 24px 48px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.app-header {
  margin-bottom: 16px;
}

.header-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.app-header h1 {
  margin: 0 0 4px;
  font-size: 22px;
  font-weight: 600;
}

.switcher-group {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.lang-switcher,
.theme-switcher {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--text-muted);
}

.lang-switcher label {
  white-space: nowrap;
}

.lang-switcher select,
.theme-switcher select {
  font: inherit;
  font-size: 13px;
  color: var(--text);
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 3px 8px;
  cursor: pointer;
  outline: none;
  transition: border-color 0.15s;
}

.lang-switcher select:hover,
.theme-switcher select:hover {
  border-color: var(--accent);
}

.lang-switcher select:focus,
.theme-switcher select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-shadow);
}

.app-header .hint {
  margin: 0;
  color: var(--text-muted);
  font-size: 13px;
}

.app-header .hint code,
.app-footer .examples code {
  background: var(--code-bg);
  padding: 1px 5px;
  border-radius: 4px;
  font-size: 12px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}

/* 编辑区域 */
.share-btn {
  font: inherit;
  font-size: 13px;
  font-weight: 500;
  color: var(--panel);
  background: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 6px;
  padding: 4px 12px;
  cursor: pointer;
  white-space: nowrap;
  transition: opacity 0.15s, transform 0.1s;
}

.share-btn:hover {
  opacity: 0.9;
}

.share-btn:active {
  transform: scale(0.97);
}

/* Toast 浮层提示 */
.toast {
  position: fixed;
  top: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(-150%);
  background: var(--status-ok);
  color: #fff;
  padding: 10px 22px;
  border-radius: 8px;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.18);
  z-index: 1000;
  font-size: 14px;
  font-weight: 500;
  opacity: 0;
  transition: opacity 0.25s ease, transform 0.25s ease;
  pointer-events: none;
  white-space: nowrap;
  max-width: 90vw;
}

.toast.is-visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

.editor {
  flex: 1;
  min-height: 60vh;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px 20px;
  font-size: 16px;
  line-height: 1.8;
  color: var(--text);
  outline: none;
  white-space: pre-wrap;
  word-break: break-word;
  overflow-wrap: anywhere;
  caret-color: var(--accent);
  box-shadow: var(--editor-shadow);
  transition: border-color 0.15s, box-shadow 0.15s;
}

.editor:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-shadow);
}

.editor:empty::before {
  content: attr(data-placeholder);
  color: var(--placeholder);
  pointer-events: none;
}

/* 结果标签 */
.result-tag {
  display: inline-block;
  background: var(--tag-bg);
  border: 1px solid var(--tag-border);
  color: var(--tag-text);
  border-radius: 6px;
  padding: 0 7px;
  margin: 0 2px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 0.92em;
  line-height: 1.5;
  font-weight: 600;
  vertical-align: baseline;
  /* 不设 user-select: none —— 否则鼠标拖选无法包含标签。
     标签的"不可编辑/光标跳过"已由 contenteditable="false" 保证，
     允许选中后，选区复制可正确得到 "1+2=3" 形式。 */
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.12s, border-color 0.12s;
}

.result-tag:hover {
  background: var(--tag-hover-bg);
  border-color: var(--tag-hover-border);
}

.result-tag.is-error {
  background: var(--tag-error-bg);
  border-color: var(--tag-error-border);
  color: var(--tag-error-text);
}

/* 让 contenteditable 内的标签不可被光标进入 */
.result-tag[contenteditable="false"] {
  /* 原子节点 */
}

/* 页脚 */
.app-footer {
  margin-top: 14px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  color: var(--text-muted);
  font-size: 12px;
}

.status {
  display: inline-flex;
  align-items: center;
}

.status::before {
  content: "";
  display: inline-block;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--status-ok);
  margin-right: 6px;
}

.status.is-working::before {
  background: var(--status-warn);
  animation: pulse 1s ease-in-out infinite;
}

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