:root {
  /* Palette */
  --bg: #f3f4f7;
  --surface: #ffffff;
  --text: #1f2430;
  --text-soft: #6b7280;
  --text-faint: #9ca3af;
  --border: #eceef1;
  --border-strong: #e2e5ea;

  --brand: #6366f1;
  --brand-soft: #eef0ff;

  --ok: #059669;
  --err: #dc2626;

  --editor-bg: #fbfbfd;
  --editor-out-bg: #fcfcfe;
  --gutter-bg: #f5f6f9;

  /* syntax highlight */
  --tok-key: #7c3aed;
  --tok-string: #16a34a;
  --tok-number: #2563eb;
  --tok-bool: #d97706;
  --tok-null: #9ca3af;
  --tok-punct: #6b7280;

  /* depth colors for brackets (循环使用) */
  --d0: #6366f1;
  --d1: #ec4899;
  --d2: #0ea5e9;
  --d3: #f59e0b;
  --d4: #10b981;
  --d5: #8b5cf6;

  --shadow-sm: 0 1px 2px rgba(16, 24, 40, 0.04), 0 1px 3px rgba(16, 24, 40, 0.06);
  --shadow-md: 0 6px 20px rgba(16, 24, 40, 0.10);

  --radius: 14px;
  --radius-sm: 11px;

  --mono: "SF Mono", "JetBrains Mono", "Fira Code", "Consolas",
    "Menlo", "Monaco", ui-monospace, monospace;
  --code-size: 13.5px;
  --code-lh: 21px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html, body {
  width: 100%;
  height: 100vh;
  overflow: hidden;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

.app { display: flex; flex-direction: column; height: 100vh; width: 100%; }

/* ---------- Header ---------- */
.header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 16px 32px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}
.header__left { display: flex; align-items: center; gap: 14px; }
.header__logo {
  display: grid; place-items: center;
  width: 44px; height: 44px; flex-shrink: 0;
  border-radius: 13px; color: #fff;
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  box-shadow: 0 6px 16px rgba(99, 102, 241, 0.35);
}
.header h1 { font-size: 22px; font-weight: 680; letter-spacing: -0.3px; }
.header__date { margin-top: 3px; font-size: 13px; color: var(--text-faint); }
.header__tools { display: flex; align-items: center; gap: 9px; }
.header__center { display: flex; align-items: center; }

/* ---------- 顶部 Tab 切换 ---------- */
.tabs {
  display: inline-flex; padding: 4px; gap: 2px;
  background: var(--bg);
  border: 1px solid var(--border-strong);
  border-radius: 12px;
}
.tab {
  height: 34px; padding: 0 22px;
  font-size: 14px; font-weight: 500;
  color: var(--text-soft);
  background: transparent; border: none; border-radius: 9px;
  cursor: pointer; transition: background .15s, color .15s;
}
.tab:hover { color: var(--brand); }
.tab.active {
  color: var(--brand); background: var(--surface);
  box-shadow: var(--shadow-sm); font-weight: 600;
}

/* ---------- 通用小控件 ---------- */
.opt-sep { width: 1px; height: 20px; background: var(--border-strong); margin: 0 2px; }

.seg {
  display: inline-flex; padding: 3px; gap: 2px;
  background: var(--bg);
  border: 1px solid var(--border-strong);
  border-radius: 10px;
}
.seg__btn {
  height: 30px; padding: 0 13px;
  font-size: 13px; font-weight: 500;
  color: var(--text-soft);
  background: transparent; border: none; border-radius: 7px;
  cursor: pointer; transition: background .15s, color .15s;
}
.seg__btn:hover { color: var(--brand); }
.seg__btn.active {
  color: var(--brand); background: var(--surface);
  box-shadow: var(--shadow-sm); font-weight: 600;
}
/* 输出 header 里的迷你缩进切换 */
.seg--mini { padding: 2px; }
.seg--mini .seg__btn { height: 24px; padding: 0 9px; font-size: 12px; border-radius: 6px; }

/* 层级步进器 */
.stepper {
  display: inline-flex; align-items: center; gap: 2px; padding: 2px;
  background: var(--bg);
  border: 1px solid var(--border-strong);
  border-radius: 8px;
}
.stepper__btn {
  width: 22px; height: 22px;
  display: inline-flex; align-items: center; justify-content: center;
  font-size: 15px; font-weight: 600; line-height: 1;
  color: var(--text-soft);
  background: transparent; border: none; border-radius: 6px;
  cursor: pointer; transition: background .15s, color .15s;
}
.stepper__btn:hover:not(:disabled) { color: var(--brand); background: var(--surface); }
.stepper__btn:disabled { opacity: .35; cursor: default; }
.stepper__val {
  min-width: 20px; text-align: center;
  font-size: 12px; font-weight: 600; color: var(--brand);
  font-variant-numeric: tabular-nums;
}

.btn {
  display: inline-flex; align-items: center; gap: 7px;
  height: 38px; padding: 0 16px;
  font-size: 14px; font-weight: 500;
  border-radius: 10px; cursor: pointer;
  transition: background .15s, color .15s, border-color .15s, transform .1s;
}
.btn:active { transform: scale(0.96); }
.btn--sm { height: 32px; padding: 0 13px; font-size: 13px; border-radius: 9px; }
.btn--ghost {
  color: var(--text-soft); background: var(--bg);
  border: 1px solid var(--border-strong);
}
.btn--ghost:hover { background: var(--brand-soft); color: var(--brand); border-color: var(--brand-soft); }
.btn--primary {
  color: #fff; background: var(--brand); border: 1px solid var(--brand);
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}
.btn--primary:hover { background: #5457e5; }

/* ---------- Editors 布局 ---------- */
.editors {
  flex: 1; min-height: 0;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  padding: 22px 32px; gap: 0; overflow: hidden;
}

/* 中间动作区：竖排动作按钮 */
.actions {
  display: flex; flex-direction: column; justify-content: center;
  gap: 12px; padding: 0 18px;
  align-self: center;
}
.action-group { display: flex; flex-direction: column; gap: 12px; }
.action-group[hidden] { display: none; }
.action-btn {
  display: inline-flex; align-items: center; gap: 9px;
  width: 100%; min-width: 132px;
  height: 44px; padding: 0 16px;
  font-size: 14px; font-weight: 600; white-space: nowrap;
  color: var(--text-soft);
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 12px;
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: background .15s, color .15s, border-color .15s, transform .1s, box-shadow .15s;
}
.action-btn:hover {
  color: var(--brand); border-color: var(--brand);
  background: var(--brand-soft);
}
.action-btn:active { transform: scale(0.96); }
.action-btn__ico { display: inline-grid; place-items: center; flex-shrink: 0; }
.action-btn--primary {
  color: #fff; background: var(--brand); border-color: var(--brand);
  box-shadow: 0 6px 16px rgba(99, 102, 241, 0.32);
}
.action-btn--primary:hover { color: #fff; background: #5457e5; border-color: #5457e5; }

.pane {
  display: flex; flex-direction: column;
  min-height: 0; min-width: 0;
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 14px;
  overflow: hidden;
}

.pane__head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 9px 14px;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0; background: var(--surface);
  min-height: 46px;
}
.pane__title { font-size: 13.5px; font-weight: 600; color: var(--text); }
.pane__meta { display: flex; align-items: center; gap: 10px; }
.pane__stat { font-size: 12px; color: var(--text-faint); font-variant-numeric: tabular-nums; }

/* 输出 header 里的工具组（缩进 + 折叠控制），仅格式化态显示 */
.out-tools { display: flex; align-items: center; gap: 8px; }
.out-tools[hidden] { display: none; }
.out-tools__max { font-size: 12px; color: var(--text-faint); font-variant-numeric: tabular-nums; }

.icon-btn {
  display: grid; place-items: center;
  width: 30px; height: 30px;
  color: var(--text-soft); background: var(--bg);
  border: 1px solid var(--border-strong); border-radius: 8px;
  cursor: pointer; transition: background .15s, color .15s;
}
.icon-btn:hover { background: var(--brand-soft); color: var(--brand); border-color: var(--brand-soft); }
.icon-btn:active { transform: scale(0.92); }
/* 文字型小按钮（折叠/展开） */
.icon-btn--text {
  width: auto; height: 26px; padding: 0 10px;
  font-size: 12px; font-weight: 500;
}

/* ---------- 输入编辑器（行号 + 高亮层 + textarea） ---------- */
.editor {
  flex: 1; min-height: 0;
  display: flex;
  background: var(--editor-bg);
  overflow: hidden;
}
.editor__gutter {
  flex-shrink: 0;
  padding: 14px 10px 14px 14px;
  text-align: right;
  font-family: var(--mono);
  font-size: var(--code-size);
  line-height: var(--code-lh);
  color: var(--text-faint);
  background: var(--gutter-bg);
  border-right: 1px solid var(--border);
  overflow: hidden;
  user-select: none;
  min-width: 46px;
}
.gutter__num { height: var(--code-lh); }
.gutter__num.is-error { color: #fff; background: var(--err); border-radius: 4px; font-weight: 600; }

.editor__scroll {
  position: relative;
  flex: 1; min-width: 0; min-height: 0;
  overflow: hidden;   /* 仅作定位容器；真正滚动交给 textarea 自身 */
}
/* 高亮层与 textarea 完全重叠，textarea 文字透明只显示光标 */
.editor__highlight,
.editor__area {
  margin: 0;
  padding: 14px 16px;
  font-family: var(--mono);
  font-size: var(--code-size);
  line-height: var(--code-lh);
  white-space: pre;
  tab-size: 2;
  border: none;
}
.editor__highlight {
  position: absolute; inset: 0;
  pointer-events: none;
  color: var(--text);
  min-width: 100%;
  width: max-content;
}
.editor__highlight .err-line {
  display: block;
  background: rgba(220, 38, 38, 0.10);
  box-shadow: inset 3px 0 0 var(--err);
  margin: 0 -16px; padding: 0 16px;
}
.editor__area {
  position: absolute; inset: 0;
  width: 100%; height: 100%;
  min-width: 100%;
  color: transparent;
  caret-color: var(--text);
  background: transparent;
  outline: none; resize: none;
  overflow: auto;   /* textarea 自身滚动，内容超长可上下/左右滚动 */
}
.editor__area::placeholder { color: var(--text-faint); }
/* 无高亮时（输入区一般直接显示原文），退化为普通可见文本 */
.editor.plain .editor__area { color: var(--text); }
.editor.plain .editor__highlight { display: none; }

/* ---------- 输出：折叠高亮树 ---------- */
.tree {
  flex: 1; min-height: 0;
  padding: 14px 16px;
  font-family: var(--mono);
  font-size: var(--code-size);
  line-height: var(--code-lh);
  color: var(--text);
  background: var(--editor-out-bg);
  overflow: auto;
  white-space: pre;
}
.tree[hidden] { display: none; }

.node { display: block; }
.node__row { display: inline; }
/* 折叠三角 */
.toggle {
  display: inline-block;
  width: 14px; margin-left: -14px;
  color: var(--text-faint);
  cursor: pointer; user-select: none;
  text-align: center;
  transition: transform .12s, color .12s;
}
.toggle:hover { color: var(--brand); }
.toggle::before { content: "▾"; font-size: 10px; }
.node.collapsed > .node__row .toggle::before { content: "▸"; }

.children { display: block; }
.children .indent { padding-left: 1.6em; }
.node.collapsed > .children { display: none; }
/* 折叠时隐藏末尾单独的闭合括号行（闭合括号改由摘要行内显示） */
.node.collapsed > .node__row.close-row { display: none; }
/* 折叠后的摘要，如 …3 项 */
.summary {
  color: var(--text-faint);
  font-style: normal;
  cursor: pointer;
}
.node:not(.collapsed) > .node__row .summary { display: none; }
.node.collapsed > .node__row .summary { display: inline; }

/* token 配色 */
.t-key    { color: var(--tok-key); }
.t-string { color: var(--tok-string); }
.t-number { color: var(--tok-number); }
.t-bool   { color: var(--tok-bool); }
.t-null   { color: var(--tok-null); }
.t-punct  { color: var(--tok-punct); }
.t-colon  { color: var(--tok-punct); }

/* 括号按深度着色 */
.br { font-weight: 600; }
.br.d0 { color: var(--d0); }
.br.d1 { color: var(--d1); }
.br.d2 { color: var(--d2); }
.br.d3 { color: var(--d3); }
.br.d4 { color: var(--d4); }
.br.d5 { color: var(--d5); }

/* ---------- 输出：纯文本（压缩/转义） ---------- */
.output-text {
  flex: 1; min-height: 0;
  margin: 0; padding: 14px 16px;
  font-family: var(--mono);
  font-size: var(--code-size);
  line-height: var(--code-lh);
  color: var(--text);
  background: var(--editor-out-bg);
  overflow: auto;
  white-space: pre-wrap;
  word-break: break-word;
}
.output-text[hidden] { display: none; }

.output-empty {
  flex: 1; display: grid; place-items: center;
  color: var(--text-faint); font-size: 14px;
  background: var(--editor-out-bg);
}
.output-empty[hidden] { display: none; }

.pane__error {
  flex-shrink: 0;
  padding: 11px 16px;
  font-family: var(--mono);
  font-size: 12.5px; line-height: 1.6;
  color: var(--err);
  background: #fef2f2;
  border-top: 1px solid #fecaca;
  white-space: pre-wrap; word-break: break-word;
}
.pane__error[hidden] { display: none; }

/* ---------- 文本比对 ---------- */
.editors[hidden], .diff[hidden] { display: none; }

.diff {
  flex: 1; min-height: 0;
  display: flex; flex-direction: column; gap: 16px;
  padding: 22px 32px; overflow: hidden;
}
.diff__top {
  flex: 0 0 36%; min-height: 150px;
  display: grid; grid-template-columns: 1fr auto 1fr;
}
.diff__result { flex: 1; min-height: 0; }
.diff__head { flex-wrap: wrap; gap: 8px; }
.diff__tools { flex-wrap: wrap; gap: 8px; }

/* 切换小胶囊（忽略空白 / 大小写 / 仅看差异） */
.chip {
  height: 26px; padding: 0 10px;
  font-size: 12px; font-weight: 500;
  color: var(--text-soft); background: var(--bg);
  border: 1px solid var(--border-strong); border-radius: 8px;
  cursor: pointer; transition: background .15s, color .15s, border-color .15s;
}
.chip:hover { color: var(--brand); background: var(--brand-soft); }
.chip.active { color: var(--brand); background: var(--brand-soft); border-color: var(--brand); font-weight: 600; }
.diff__tools .icon-btn { width: 26px; height: 26px; font-size: 14px; }

/* 差异统计 */
.diff-stat { display: inline-flex; align-items: center; gap: 8px; font-size: 12px; font-variant-numeric: tabular-nums; }
.ds { color: var(--text-faint); }
.ds--add { color: var(--ok); font-weight: 600; }
.ds--del { color: var(--err); font-weight: 600; }
.ds--same { color: var(--ok); font-weight: 600; }

/* 差异内容区 */
.dbody {
  position: relative;
  flex: 1; min-height: 0; overflow: auto;
  font-family: var(--mono); font-size: var(--code-size); line-height: var(--code-lh);
  background: var(--editor-out-bg);
}
.dbody[hidden] { display: none; }
.drow { display: flex; }
.dcell { flex: 1 1 50%; min-width: 0; display: flex; }
.dcell + .dcell { border-left: 1px solid var(--border-strong); }
.dno {
  flex: 0 0 52px; padding: 0 10px 0 6px; text-align: right;
  color: var(--text-faint); background: var(--gutter-bg);
  user-select: none; font-variant-numeric: tabular-nums;
}
.dtxt {
  flex: 1; min-width: 0; min-height: var(--code-lh);
  padding: 0 12px; color: var(--text);
  white-space: pre-wrap; word-break: break-all;
}
.dcell.del { background: rgba(239, 68, 68, 0.09); }
.dcell.del .dno { background: rgba(239, 68, 68, 0.16); color: #b91c1c; }
.dcell.add { background: rgba(16, 185, 129, 0.10); }
.dcell.add .dno { background: rgba(16, 185, 129, 0.18); color: #047857; }
.dcell.empty {
  background: repeating-linear-gradient(45deg, transparent 0 6px, rgba(31, 36, 48, 0.035) 6px 12px);
}
.dcell.del mark.chg { background: rgba(239, 68, 68, 0.32); }
.dcell.add mark.chg { background: rgba(16, 185, 129, 0.34); }
mark.chg { color: inherit; border-radius: 3px; padding: 1px 0; }

/* 统一视图 */
.drow.u .dno { flex: 0 0 48px; }
.drow.u .dsign { flex: 0 0 22px; text-align: center; color: var(--text-faint); user-select: none; font-weight: 600; }
.drow.u.del { background: rgba(239, 68, 68, 0.09); }
.drow.u.del .dno { background: rgba(239, 68, 68, 0.16); color: #b91c1c; }
.drow.u.del .dsign { color: var(--err); }
.drow.u.add { background: rgba(16, 185, 129, 0.10); }
.drow.u.add .dno { background: rgba(16, 185, 129, 0.18); color: #047857; }
.drow.u.add .dsign { color: var(--ok); }
.drow.u.del mark.chg { background: rgba(239, 68, 68, 0.32); }
.drow.u.add mark.chg { background: rgba(16, 185, 129, 0.34); }

/* 折叠段 */
.dfold {
  display: flex; align-items: center; justify-content: center;
  height: 30px; font-family: inherit; font-size: 12px;
  color: var(--brand); background: var(--brand-soft);
  border-top: 1px solid var(--border); border-bottom: 1px solid var(--border);
  cursor: pointer; user-select: none;
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", sans-serif;
}
.dfold:hover { background: #e2e5ff; }

/* 当前定位的差异块 */
.drow.is-current { box-shadow: inset 3px 0 0 var(--brand); filter: saturate(1.35); }

/* ---------- Footer ---------- */
.footer {
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 32px;
  background: var(--surface);
  border-top: 1px solid var(--border);
  flex-shrink: 0;
}
.footer__status { font-size: 13px; color: var(--text-soft); display: inline-flex; align-items: center; gap: 8px; }
.footer__status::before {
  content: ""; width: 7px; height: 7px; border-radius: 50%;
  background: var(--text-faint); transition: background .2s;
}
.footer__status.is-ok::before { background: var(--ok); }
.footer__status.is-err::before { background: var(--err); }
.footer__status.is-ok { color: var(--ok); }
.footer__status.is-err { color: var(--err); }
.footer__hint { font-size: 12.5px; color: var(--text-faint); }

/* ---------- Toast ---------- */
.toast {
  position: fixed; left: 50%; bottom: 36px;
  transform: translateX(-50%) translateY(12px);
  padding: 11px 20px; font-size: 14px;
  color: #fff; background: #1f2430;
  border-radius: 11px; box-shadow: var(--shadow-md);
  opacity: 0; pointer-events: none;
  transition: opacity .22s, transform .22s;
  z-index: 100;
}
.toast[hidden] { display: block; }
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
.toast.toast--error { background: var(--err); }
.toast.toast--success { background: var(--ok); }

/* ---------- Responsive ---------- */
@media (max-width: 720px) {
  .header, .editors, .footer { padding-left: 18px; padding-right: 18px; }
  .header { flex-wrap: wrap; gap: 10px; }
  .editors { grid-template-columns: 1fr; grid-template-rows: 1fr auto 1fr; }
  .actions { flex-direction: row; justify-content: center; flex-wrap: wrap; padding: 4px 0; }
  .action-group { flex-direction: row; justify-content: center; flex-wrap: wrap; }
  .action-btn { width: auto; min-width: 0; }
  .diff { padding-left: 18px; padding-right: 18px; }
  .diff__top { flex-basis: auto; grid-template-columns: 1fr; grid-template-rows: 1fr auto 1fr; }
}