:root {
  --bg: #ffffff;
  --text: #1f2a37;
  --muted: #6b7280;
  --line: #e5e7eb;
  --panel: #f9fafb;
  --panel-strong: #f2f5f7;
  --accent: #0f766e;
  --math-kb-height: 0px;
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Source Han Sans SC", sans-serif;
}

body {
  display: flex;
  flex-direction: column;
}

.topbar {
  height: 56px;
  border-bottom: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 18px;
  background: linear-gradient(90deg, #ffffff 0%, #f8fbff 100%);
}

.brand {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.3px;
}

.topbar-right {
  display: flex;
  align-items: center;
  gap: 16px;
}

.download-btn {
  border: 1px solid #0f766e;
  background: #0f766e;
  color: #fff;
  border-radius: 8px;
  padding: 7px 12px;
  cursor: pointer;
  font: inherit;
}

.download-btn:hover {
  filter: brightness(0.95);
}

.switch-wrap {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--muted);
  font-size: 13px;
  user-select: none;
}

.switch-wrap input {
  accent-color: var(--accent);
}

.help {
  color: var(--muted);
  font-size: 13px;
}

.app-shell {
  flex: 1;
  min-height: 0;
  display: flex;
}

.toolbar-panel {
  width: 20%;
  min-width: 220px;
  border-right: 1px solid var(--line);
  background: var(--panel);
  padding: 16px 14px;
  overflow-y: auto;
  position: relative;
  z-index: 50;
}

.toolbar-panel h2 {
  margin: 0 0 14px;
  font-size: 18px;
}

.tool-group {
  margin-bottom: 16px;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fff;
}

.tool-group h3 {
  margin: 0 0 8px;
  font-size: 14px;
  color: var(--muted);
}

.tool-btn {
  width: 100%;
  margin: 6px 0;
  border: 1px solid #d1d5db;
  background: var(--panel-strong);
  color: var(--text);
  border-radius: 8px;
  padding: 8px 10px;
  text-align: left;
  cursor: pointer;
  transition: all 140ms ease;
  position: relative;
}

.tool-btn:hover {
  transform: translateY(-1px);
  border-color: var(--accent);
}

.tool-btn[data-shortcut]:hover::after,
.tool-btn[data-shortcut]:focus-visible::after {
  content: attr(data-shortcut);
  position: absolute;
  right: 8px;
  top: 50%;
  transform: translateY(-50%);
  background: #111827;
  color: #f9fafb;
  border: 1px solid #374151;
  border-radius: 6px;
  padding: 3px 8px;
  font-size: 12px;
  white-space: nowrap;
  z-index: 200;
  pointer-events: none;
}

#mathTemplateFields.grid-mode {
  overflow-x: auto;
}

.template-grid {
  display: grid;
  gap: 8px;
  margin-top: 6px;
}

.template-grid input {
  width: 100%;
  margin-top: 0;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  padding: 7px 8px;
  font: inherit;
  min-width: 0;
}

.heading-picker {
  position: relative;
}

.heading-main {
  margin-bottom: 0;
}

.heading-menu {
  position: absolute;
  left: 0;
  top: calc(100% + 4px);
  width: 100%;
  background: #ffffff;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  padding: 6px;
  box-shadow: 0 8px 20px rgba(15, 23, 42, 0.12);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-4px);
  transition: all 140ms ease;
  z-index: 30;
}

.heading-picker:hover .heading-menu,
.heading-picker:focus-within .heading-menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.editor-panel {
  width: 80%;
  display: flex;
  min-height: 0;
  padding-bottom: 0;
  transition: padding-bottom 160ms ease;
}

body.math-open .editor-panel {
  padding-bottom: var(--math-kb-height);
}

.editor-wrap {
  position: relative;
  display: flex;
  flex: 1;
  min-height: 0;
  background: #fff;
}

.line-numbers {
  width: 64px;
  border-right: 1px solid var(--line);
  padding: 10px 0 calc(10px + var(--math-kb-height));
  text-align: right;
  color: #9ca3af;
  font-family: "JetBrains Mono", monospace;
  font-size: 13px;
  line-height: 1.6;
  overflow: hidden;
  user-select: none;
  flex-shrink: 0;
  z-index: 3;
  scroll-behavior: auto;
}

.line-number-item {
  padding: 0 8px;
  height: calc(14px * 1.6);
  display: flex;
  align-items: center;
  justify-content: flex-end;
  border-bottom: 1px solid transparent;
  box-sizing: border-box;
}

.guide-layer {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 64px;
  padding: 10px 14px calc(10px + var(--math-kb-height));
  overflow: hidden;
  pointer-events: none;
  z-index: 0;
  scroll-behavior: auto;
}

.guide-line {
  height: calc(14px * 1.6);
  border-bottom: 1px solid transparent;
  box-sizing: border-box;
}

.render-layer {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 64px;
  padding: 10px 14px;
  overflow: hidden;
  word-break: break-word;
  font-family: "JetBrains Mono", monospace;
  font-size: 14px;
  line-height: 1.6;
  color: #1f2937;
  pointer-events: none;
  z-index: 1;
  scroll-behavior: auto;
  overscroll-behavior: none;
  padding-bottom: calc(10px + var(--math-kb-height));
}

.render-line {
  min-height: 1.6em;
  overflow: hidden;
}

.render-line > * {
  margin-top: 0;
  margin-bottom: 0;
}

.render-layer p,
.render-layer ul,
.render-layer ol,
.render-layer pre,
.render-layer blockquote,
.render-layer table,
.render-layer h1,
.render-layer h2,
.render-layer h3,
.render-layer h4,
.render-layer h5,
.render-layer h6 {
  margin-bottom: 10px;
}

.render-layer h1,
.render-layer h2,
.render-layer h3,
.render-layer h4 {
  font-family: "Source Han Sans SC", sans-serif;
  line-height: 1.35;
}

.render-layer h1 { font-size: 27px; }
.render-layer h2 { font-size: 23px; }
.render-layer h3 { font-size: 19px; }
.render-layer h4 { font-size: 16px; }

.render-layer code {
  font-family: "JetBrains Mono", monospace;
  background: #f3f4f6;
  border-radius: 5px;
  padding: 1px 4px;
}

.render-layer strong,
.render-layer b {
  color: #0b8f84;
  font-weight: 800;
}

.render-layer em,
.render-layer i {
  color: #0b8f84;
}

.render-line.code-fence-line {
  background: #f8fafc;
  border-left: 1px solid #d1d5db;
  border-right: 1px solid #d1d5db;
}

.render-line.code-fence-line code {
  display: block;
  padding: 8px 10px;
  background: transparent;
  border-radius: 0;
  font-family: "JetBrains Mono", monospace;
}

/* Local fallback for GitHub-like syntax colors when remote hljs theme is unavailable. */
.render-layer .hljs {
  color: #24292e;
  background: transparent;
}

.render-layer .hljs-comment,
.render-layer .hljs-quote {
  color: #6a737d;
  font-style: italic;
}

.render-layer .hljs-keyword,
.render-layer .hljs-selector-tag,
.render-layer .hljs-subst,
.render-layer .hljs-doctag,
.render-layer .hljs-meta .hljs-keyword {
  color: #d73a49;
}

.render-layer .hljs-string,
.render-layer .hljs-regexp,
.render-layer .hljs-attr,
.render-layer .hljs-template-tag,
.render-layer .hljs-template-variable,
.render-layer .hljs-addition {
  color: #032f62;
}

.render-layer .hljs-title,
.render-layer .hljs-section,
.render-layer .hljs-name,
.render-layer .hljs-selector-id,
.render-layer .hljs-selector-class,
.render-layer .hljs-type,
.render-layer .hljs-built_in,
.render-layer .hljs-class .hljs-title {
  color: #6f42c1;
}

.render-layer .hljs-number,
.render-layer .hljs-literal,
.render-layer .hljs-symbol,
.render-layer .hljs-bullet,
.render-layer .hljs-link {
  color: #005cc5;
}

.render-layer .hljs-variable,
.render-layer .hljs-params,
.render-layer .hljs-property,
.render-layer .hljs-operator,
.render-layer .hljs-punctuation,
.render-layer .hljs-deletion {
  color: #24292e;
}

.render-line.code-fence-start {
  border-top: 1px solid #d1d5db;
  border-top-left-radius: 8px;
  border-top-right-radius: 8px;
}

.render-line.code-fence-middle {
  border-top: 0;
}

.render-line.code-fence-end {
  border-bottom: 1px solid #d1d5db;
  border-bottom-left-radius: 8px;
  border-bottom-right-radius: 8px;
}

.render-line.code-fence-single {
  border-top: 1px solid #d1d5db;
  border-bottom: 1px solid #d1d5db;
  border-radius: 8px;
}

#editor {
  flex: 1;
  border: 0;
  resize: none;
  padding: 10px 14px;
  outline: none;
  font-family: "JetBrains Mono", monospace;
  font-size: 14px;
  line-height: 1.6;
  color: var(--text);
  caret-color: #111827;
  background: transparent;
  overflow: auto;
  position: relative;
  z-index: 2;
  scrollbar-width: thin;
  scroll-behavior: auto;
  overscroll-behavior: none;
  padding-bottom: calc(10px + var(--math-kb-height));
}

#editor::placeholder {
  color: #9ca3af;
}

.editor-wrap.render-on #editor {
  opacity: 0;
  pointer-events: none;
}

.editor-wrap.render-on .render-layer {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  overflow: auto;
}

.editor-wrap:not(.render-on) .render-layer {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.render-layer table {
  border-collapse: collapse;
  width: 100%;
}

.render-layer th,
.render-layer td {
  border: 1px solid #d1d5db;
  padding: 6px 8px;
}

.render-layer pre {
  border: 1px solid #d1d5db;
  border-radius: 8px;
  padding: 10px;
  overflow: auto;
  margin: 8px 0;
  background: #f8fafc;
}

.render-layer pre code {
  background: transparent;
  padding: 0;
}

.math-keyboard {
  position: fixed;
  left: 20%;
  right: 0;
  bottom: 0;
  border-top: 1px solid var(--line);
  background: #ffffff;
  box-shadow: 0 -5px 20px rgba(15, 23, 42, 0.08);
  transform: translateY(100%);
  transition: transform 180ms ease;
  z-index: 20;
}

.math-keyboard.open {
  transform: translateY(0);
}

.math-title {
  padding: 8px 12px 4px;
  color: var(--muted);
  font-size: 13px;
}

.math-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(60px, 1fr));
  gap: 5px;
  padding: 8px 10px 12px;
}

.math-key {
  border: 1px solid #d1d5db;
  background: #f8fafc;
  border-radius: 8px;
  padding: 6px 4px;
  text-align: center;
  cursor: pointer;
  font-family: "JetBrains Mono", monospace;
  font-size: 13px;
  min-height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  white-space: nowrap;
}

.math-key:hover {
  border-color: var(--accent);
}

dialog {
  border: 1px solid #d1d5db;
  border-radius: 12px;
  padding: 0;
}

dialog::backdrop {
  background: rgba(0, 0, 0, 0.2);
}

.dialog-form {
  padding: 14px;
  min-width: 300px;
}

.dialog-form h3 {
  margin: 0 0 10px;
}

.dialog-form label {
  display: block;
  margin: 8px 0;
  color: var(--muted);
}

.dialog-form input,
.dialog-form select {
  width: 100%;
  margin-top: 4px;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  padding: 8px;
  font: inherit;
}

.dialog-actions {
  display: flex;
  justify-content: flex-end;
  gap: 8px;
  margin-top: 12px;
}

.dialog-actions button {
  border: 1px solid #d1d5db;
  background: #fff;
  border-radius: 8px;
  padding: 7px 12px;
  cursor: pointer;
}

body.show-line-guides .line-number-item,
body.show-line-guides .guide-line {
  border-bottom-color: #edf1f5;
}

@media (max-width: 980px) {
  .app-shell {
    flex-direction: column;
  }

  .toolbar-panel,
  .editor-panel {
    width: 100%;
  }

  .toolbar-panel {
    min-width: unset;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .math-keyboard {
    left: 0;
  }

  .math-grid {
    grid-template-columns: repeat(4, minmax(70px, 1fr));
  }
}