:root,
[data-theme="light"] {
    color-scheme: light;
    --bg-color: #fff;
    --text-color: #24292f;
    --muted-text: #57606a;
    --border-color: #d0d7de;
    --toolbar-bg: #f6f8fa;
    --editor-bg: #f6f8fa;
    --preview-bg: #fff;
    --code-bg: #f6f8fa;
    --inline-code-bg: rgba(175, 184, 193, 0.2);
    --link-color: #0969da;
    --btn-bg: #2da44e;
    --btn-bg-hover: #2c974b;
    --btn-border: rgba(27, 31, 36, 0.15);
    --btn-text: #fff;
    --theme-btn-bg: transparent;
    --theme-btn-bg-hover: #eaeef2;
    --theme-btn-text: #24292f;
    --splitter-hover: #0969da;
    --drop-bg: rgba(255, 255, 255, 0.8);
    --drop-color: #0969da;
    --drop-border: #0969da;
    --banner-text: #24292f;
    --banner-error: #ffebe9;
    --banner-error-border: #ff8182;
    --banner-warning: #fff8c5;
    --banner-warning-border: #d4a72c;
    --blockquote-border: #d0d7de;
    --table-stripe: #f6f8fa;
    --broken-image-border: #d1242f;
    --hljs-bg: #fff;
    --hljs-color: #24292e;
    --hljs-keyword: #d73a49;
    --hljs-title: #6f42c1;
    --hljs-attr: #005cc5;
    --hljs-string: #032f62;
    --hljs-built-in: #e36209;
    --hljs-comment: #6a737d;
    --hljs-name: #22863a;
    --hljs-section: #005cc5;
    --hljs-bullet: #735c0f;
    --hljs-addition: #22863a;
    --hljs-addition-bg: #f0fff4;
    --hljs-deletion: #b31d28;
    --hljs-deletion-bg: #ffeef0;
}

[data-theme="dark"] {
    color-scheme: dark;
    --bg-color: #0d1117;
    --text-color: #e6edf3;
    --muted-text: #8b949e;
    --border-color: #30363d;
    --toolbar-bg: #010409;
    --editor-bg: #0d1117;
    --preview-bg: #0d1117;
    --code-bg: #161b22;
    --inline-code-bg: rgba(110, 118, 129, 0.4);
    --link-color: #4493f8;
    --btn-bg: #238636;
    --btn-bg-hover: #2ea043;
    --btn-border: rgba(240, 246, 252, 0.1);
    --btn-text: #fff;
    --theme-btn-bg: transparent;
    --theme-btn-bg-hover: #21262d;
    --theme-btn-text: #e6edf3;
    --splitter-hover: #4493f8;
    --drop-bg: rgba(13, 17, 23, 0.85);
    --drop-color: #4493f8;
    --drop-border: #4493f8;
    --banner-text: #e6edf3;
    --banner-error: #3d1114;
    --banner-error-border: #f85149;
    --banner-warning: #3d2e00;
    --banner-warning-border: #d29922;
    --blockquote-border: #30363d;
    --table-stripe: #161b22;
    --broken-image-border: #f85149;
    --hljs-bg: #0d1117;
    --hljs-color: #c9d1d9;
    --hljs-keyword: #ff7b72;
    --hljs-title: #d2a8ff;
    --hljs-attr: #79c0ff;
    --hljs-string: #a5d6ff;
    --hljs-built-in: #ffa657;
    --hljs-comment: #8b949e;
    --hljs-name: #7ee787;
    --hljs-section: #1f6feb;
    --hljs-bullet: #f2cc60;
    --hljs-addition: #aff5b4;
    --hljs-addition-bg: #033a16;
    --hljs-deletion: #ffdcd7;
    --hljs-deletion-bg: #67060c;
}

* {
    box-sizing: border-box;
}

body, html {
    margin: 0;
    padding: 0;
    height: 100vh;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    background: var(--bg-color);
    color: var(--text-color);
}

#toolbar {
    padding: 10px 20px;
    background: var(--toolbar-bg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 8px;
}

.actions {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
}

#toolbar h1 {
    font-size: 16px;
    margin: 0;
    color: var(--text-color);
}

button {
    background: var(--btn-bg);
    color: var(--btn-text);
    border: 1px solid var(--btn-border);
    border-radius: 6px;
    padding: 5px 16px;
    font-size: 14px;
    cursor: pointer;
    margin-left: 8px;
}
button:hover { background: var(--btn-bg-hover); }

#btn-theme {
    background: var(--theme-btn-bg);
    color: var(--theme-btn-text);
    border: 1px solid var(--border-color);
    min-width: 4.5em;
}
#btn-theme:hover {
    background: var(--theme-btn-bg-hover);
}

.theme-label-light { display: none; }
[data-theme="dark"] .theme-label-dark { display: none; }
[data-theme="dark"] .theme-label-light { display: inline; }

.banner {
    padding: 10px;
    text-align: center;
    font-weight: bold;
    color: var(--banner-text);
}
.banner.hidden { display: none; }
.banner.error { background: var(--banner-error); border-bottom: 1px solid var(--banner-error-border); }
.banner.warning { background: var(--banner-warning); border-bottom: 1px solid var(--banner-warning-border); }

#workspace {
    display: flex;
    flex: 1;
    position: relative;
    overflow: hidden;
    background: var(--bg-color);
}

.panel {
    display: flex;
    flex-direction: column;
    min-width: 200px;
    height: 100%;
}

#source-panel {
    width: 50%;
    position: relative;
}

.source-meta {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 6px 12px;
    border-bottom: 1px solid var(--border-color);
    background: var(--toolbar-bg);
    font-size: 12px;
    color: var(--muted-text);
    min-height: 28px;
    flex-shrink: 0;
}

.source-kind {
    font-weight: 600;
    letter-spacing: 0.03em;
    color: var(--text-color);
    flex-shrink: 0;
}

.source-name {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
#preview-panel {
    flex: 1;
    overflow-y: auto;
    background: var(--preview-bg);
    padding: 30px;
}

#editor {
    flex: 1;
    border: none;
    resize: none;
    padding: 20px;
    font-family: ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace;
    font-size: 14px;
    outline: none;
    background: var(--editor-bg);
    color: var(--text-color);
}

#splitter {
    width: 5px;
    background: var(--border-color);
    cursor: col-resize;
    z-index: 10;
}
#splitter:hover {
    background: var(--splitter-hover);
}

#drop-zone {
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: var(--drop-bg);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 24px;
    font-weight: bold;
    color: var(--drop-color);
    border: 4px dashed var(--drop-border);
    z-index: 20;
}
#drop-zone.hidden {
    display: none;
}

/* GitHub Markdown Basic Styles */
.markdown-body {
    font-size: 16px;
    line-height: 1.5;
    word-wrap: break-word;
    color: var(--text-color);
}
.markdown-body h1, .markdown-body h2 {
    border-bottom: 1px solid var(--border-color);
    padding-bottom: .3em;
    margin-top: 24px;
    margin-bottom: 16px;
}
.markdown-body img {
    max-width: 100%;
    box-sizing: content-box;
}
.markdown-body .broken-image {
    border: 1px dashed var(--broken-image-border);
    padding: 10px;
}
.markdown-body pre {
    background-color: var(--code-bg);
    border-radius: 6px;
    padding: 16px;
    overflow: auto;
}
.markdown-body code {
    font-family: ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace;
    background-color: var(--inline-code-bg);
    border-radius: 6px;
    padding: .2em .4em;
}
.markdown-body pre code {
    background-color: transparent;
    padding: 0;
}
.markdown-body blockquote {
    padding: 0 1em;
    color: var(--muted-text);
    border-left: .25em solid var(--blockquote-border);
    margin: 0;
}
.markdown-body table {
    border-spacing: 0;
    border-collapse: collapse;
    margin-bottom: 16px;
}
.markdown-body table th, .markdown-body table td {
    padding: 6px 13px;
    border: 1px solid var(--border-color);
}
.markdown-body table tr:nth-child(2n) {
    background-color: var(--table-stripe);
}
.markdown-body input[type="checkbox"] {
    margin: 0 0.2em 0.25em -1.6em;
    vertical-align: middle;
}
.markdown-body .task-list-item {
    list-style-type: none;
}
.markdown-body ul, .markdown-body ol {
    padding-left: 2em;
    margin-top: 0;
    margin-bottom: 16px;
}
.markdown-body p {
    margin-top: 0;
    margin-bottom: 16px;
}
.markdown-body a {
    color: var(--link-color);
    text-decoration: none;
}
.markdown-body a:hover {
    text-decoration: underline;
}

/* highlight.js GitHub (light) / GitHub Dark — token colors via theme variables */
.hljs {
    color: var(--hljs-color);
    background: var(--hljs-bg);
}
.hljs-doctag,
.hljs-keyword,
.hljs-meta .hljs-keyword,
.hljs-template-tag,
.hljs-template-variable,
.hljs-type,
.hljs-variable.language_ {
    color: var(--hljs-keyword);
}
.hljs-title,
.hljs-title.class_,
.hljs-title.class_.inherited__,
.hljs-title.function_ {
    color: var(--hljs-title);
}
.hljs-attr,
.hljs-attribute,
.hljs-literal,
.hljs-meta,
.hljs-number,
.hljs-operator,
.hljs-selector-attr,
.hljs-selector-class,
.hljs-selector-id,
.hljs-variable {
    color: var(--hljs-attr);
}
.hljs-meta .hljs-string,
.hljs-regexp,
.hljs-string {
    color: var(--hljs-string);
}
.hljs-built_in,
.hljs-symbol {
    color: var(--hljs-built-in);
}
.hljs-code,
.hljs-comment,
.hljs-formula {
    color: var(--hljs-comment);
}
.hljs-name,
.hljs-quote,
.hljs-selector-pseudo,
.hljs-selector-tag {
    color: var(--hljs-name);
}
.hljs-subst {
    color: var(--hljs-color);
}
.hljs-section {
    color: var(--hljs-section);
    font-weight: 700;
}
.hljs-bullet {
    color: var(--hljs-bullet);
}
.hljs-emphasis {
    color: var(--hljs-color);
    font-style: italic;
}
.hljs-strong {
    color: var(--hljs-color);
    font-weight: 700;
}
.hljs-addition {
    color: var(--hljs-addition);
    background-color: var(--hljs-addition-bg);
}
.hljs-deletion {
    color: var(--hljs-deletion);
    background-color: var(--hljs-deletion-bg);
}