:root {
  --primary-color: #4a6fa5;
  --bg-color: #ffffff;
  --text-color: #333333;
  --border-color: #e0e0e0;
  --header-bg: #f8f9fa;
  --toolbar-bg: #f1f3f5;
  --preview-bg: #ffffff;
  --code-bg: #f6f8fa;
  --shadow: 0 1px 5px rgba(0, 0, 0, 0.08);
  --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', 'Monaco', monospace;
  --scrollbar-bg: #f1f1f1;
  --scrollbar-thumb-bg: #c1c1c1;
  --scrollbar-thumb-hover-bg: #a8a8a8;
}

[data-theme="dark"] {
  --primary-color: #5d8ff6;
  --bg-color: #1e1e1e;
  --text-color: #e0e0e0;
  --border-color: #333;
  --header-bg: #252526;
  --toolbar-bg: #2d2d2d;
  --preview-bg: #1e1e1e;
  --code-bg: #2d2d2d;
  --shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
  --scrollbar-bg: #2d2d2d;
  --scrollbar-thumb-bg: #555;
  --scrollbar-thumb-hover-bg: #777;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  scrollbar-width: thin;
  scrollbar-color: var(--scrollbar-thumb-bg) var(--scrollbar-bg);
}

/* Works on Chrome, Edge, and Safari */
::-webkit-scrollbar {
  width: 12px;
  height: 12px;
}

::-webkit-scrollbar-track {
  background: var(--scrollbar-bg);
}

::-webkit-scrollbar-thumb {
  background-color: var(--scrollbar-thumb-bg);
  border-radius: 10px;
  border: 3px solid var(--scrollbar-bg);
}

::-webkit-scrollbar-thumb:hover {
  background-color: var(--scrollbar-thumb-hover-bg);
}


body {
  margin: 0;
  font-family: var(--font-main);
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  display: flex;
  flex-direction: column;
  height: 100vh;
  transition: background-color 0.3s, color 0.3s;
}

.app-header {
  background-color: var(--header-bg);
  border-bottom: 1px solid var(--border-color);
  padding: 0.5rem 1rem;
  box-shadow: var(--shadow);
  z-index: 10;
  position: sticky;
  top: 0;
  transition: background-color 0.3s, border-color 0.3s;
}

.header-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1400px;
  margin: 0 auto;
  padding: 0.5rem 0;
  gap: 1rem;
}

h1 {
  font-size: 1.4rem;
  font-weight: 600;
  color: var(--primary-color);
  margin: 0;
  white-space: nowrap;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.view-mode {
  display: flex;
  background: var(--bg-color);
  border-radius: 6px;
  border: 1px solid var(--border-color);
  overflow: hidden;
}

.view-btn {
  background: none;
  border: none;
  padding: 0.4rem 0.8rem;
  cursor: pointer;
  color: var(--text-color);
  opacity: 0.7;
  transition: all 0.2s;
  border-left: 1px solid var(--border-color);
}
.view-btn:first-child { border-left: none; }
.view-btn:hover { background: var(--primary-color); color: white; opacity: 1; }
.view-btn.active { background: var(--primary-color); color: white; opacity: 1; }
.view-btn i { margin-right: 6px; }

.toolbar {
  display: flex;
  gap: 0.25rem;
  padding: 0.5rem 1rem;
  background-color: var(--toolbar-bg);
  border-bottom: 1px solid var(--border-color);
  overflow-x: auto;
  white-space: nowrap;
}

.toolbar-group { display: flex; gap: 0.25rem; }
.toolbar-separator { border-left: 1px solid var(--border-color); margin: 0 0.5rem; }
.toolbar button {
  background: none;
  border: 1px solid transparent;
  border-radius: 4px;
  color: var(--text-color);
  cursor: pointer;
  padding: 0.5rem;
  font-size: 1rem;
  transition: all 0.2s;
}
.toolbar button:hover { background-color: var(--primary-color); color: white; }

.editor-container {
  display: flex;
  flex: 1;
  overflow: hidden;
}

.editor-pane, .preview-pane {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
  transition: all 0.3s ease;
  background-color: var(--bg-color);
  position: relative;
  overflow-y: auto;
}

.editor-pane {
  border-right: 1px solid var(--border-color);
}

.editor-container.editor-view .preview-pane,
.editor-container.preview-view .editor-pane {
  flex: 0;
  min-width: 0;
  width: 0;
  opacity: 0;
  pointer-events: none;
  border: none;
}

.pane-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.5rem 1rem;
  background-color: var(--toolbar-bg);
  border-bottom: 1px solid var(--border-color);
  font-size: 0.9rem;
  font-weight: 500;
  position: sticky;
  top: 0;
  z-index: 5;
}

#editor {
  flex: 1;
  padding: 1rem;
  border: none;
  resize: none;
  font-family: var(--font-mono);
  font-size: 1rem;
  line-height: 1.7;
  background-color: var(--bg-color);
  color: var(--text-color);
  outline: none;
  transition: background-color 0.3s, color 0.3s;
  white-space: pre;
  overflow-wrap: normal;
  overflow-x: auto;
}

#preview {
  padding: 1rem;
  flex: 1;
}

/* --- Markdown Styling --- */
.markdown-body {
  max-width: 800px;
  margin: 0 auto;
  padding: 1rem;
  line-height: 1.7;
}

.markdown-body a {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 500;
  transition: text-decoration 0.2s ease-in-out;
}

.markdown-body a:hover {
  text-decoration: underline;
}

.markdown-body pre {
  background-color: var(--code-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 1rem;
  overflow-x: auto;
  position: relative;
}
.markdown-body code {
  font-family: var(--font-mono);
  background-color: var(--code-bg);
  padding: 0.2em 0.4em;
  border-radius: 3px;
  font-size: 85%;
}
.markdown-body pre code { background: none; padding: 0; }
.markdown-body table { border-collapse: collapse; width: 100%; }
.markdown-body th, .markdown-body td { border: 1px solid var(--border-color); padding: 0.5rem; }

.copy-code-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: 4px;
  padding: 0.25rem 0.5rem;
  font-size: 0.8rem;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.2s;
}
pre:hover .copy-code-btn { opacity: 1; }
.copy-code-btn:hover { background: #3a5f95; }
[data-theme="dark"] .copy-code-btn:hover { background: #7d9ffc; }

.app-footer {
  background-color: var(--header-bg);
  border-top: 1px solid var(--border-color);
  padding: 0.25rem 1rem;
  font-size: 0.8rem;
  transition: background-color 0.3s, border-color 0.3s;
}
.status-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1400px;
  margin: 0 auto;
  color: var(--text-color);
  opacity: 0.8;
  gap: 1rem;
}
.status-left, .status-right { display: flex; gap: 1rem; }

.btn, .icon-btn {
  background-color: var(--primary-color);
  color: white;
  border: 1px solid transparent;
  border-radius: 4px;
  padding: 8px 12px;
  cursor: pointer;
  font-size: 14px;
  transition: all 0.2s;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  white-space: nowrap;
}
.icon-btn { padding: 0.5rem; }
.btn:hover, .icon-btn:hover {
  background-color: #3a5f95;
  transform: translateY(-1px);
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}
[data-theme="dark"] .btn:hover, [data-theme="dark"] .icon-btn:hover {
  background-color: #7d9ffc;
}

#toastContainer {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 1000;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.toast {
  background-color: #333;
  color: white;
  padding: 12px 20px;
  border-radius: 6px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  font-size: 0.9rem;
  opacity: 0;
  transform: translateY(20px);
  animation: toast-in 0.5s forwards;
}
@keyframes toast-in {
  to { opacity: 1; transform: translateY(0); }
}

.drag-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  z-index: 2000;
  display: none;
  justify-content: center;
  align-items: center;
  pointer-events: none;
}
.drag-overlay.visible { display: flex; }
.drag-overlay-content {
  text-align: center;
  color: white;
  padding: 40px;
  border: 2px dashed white;
  border-radius: 12px;
  background: rgba(0, 0, 0, 0.2);
  backdrop-filter: blur(5px);
}

@media (max-width: 768px) {
  .btn-text, .view-label { display: none; }
  .header-actions { gap: 0.25rem; }
  .view-btn i { margin-right: 0; }
  .editor-container { flex-direction: column; }
  .editor-pane, .preview-pane { width: 100%; height: 50%; border: none; }
  .editor-pane { border-bottom: 1px solid var(--border-color); }
}