body {
    margin: 0;
    font-family: monospace;
    background: #0f1115;
    color: #e6e6e6;
    height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    padding: 10px 16px;
    background: #161a22;
    border-bottom: 1px solid #2a2f3a;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

header h1 {
    font-size: 14px;
    margin: 0;
    opacity: 0.8;
}

header h1 > img {
    vertical-align: middle;
    width: 24px;
    height: 24px;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 8px;
}

.file-status {
    min-width: 220px;
    font-size: 12px;
    color: #7f8ea3;
    text-align: right;
}

button {
    background: #2d6cdf;
    color: white;
    border: none;
    padding: 6px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-family: monospace;
}

button:hover {
    background: #3a7bfd;
}

main {
    flex: 1;
    display: grid;
    grid-template-columns: 1fr 1fr;
    min-height: 0;
}

.editor {
    --preview-height: 280px;
    border-right: 1px solid #2a2f3a;
    display: flex;
    flex-direction: column;
    min-height: 0;
}

.example-tabs {
    display: flex;
    align-items: center;
    gap: 12px;
    min-height: 46px;
    padding: 0 12px;
    border-bottom: 1px solid #2a2f3a;
    background: #12161d;
}

.example-tabs-label {
    flex: 0 0 auto;
    font-size: 11px;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: #7f8ea3;
}

.example-tabs-list {
    display: flex;
    gap: 8px;
    overflow-x: auto;
    scrollbar-width: thin;
}

.run-mode-toggle {
    margin-left: auto;
    display: inline-flex;
    gap: 6px;
    padding: 4px;
    border: 1px solid #2a2f3a;
    border-radius: 999px;
    background: #0d1117;
}

.run-mode-button {
    background: transparent;
    color: #8ea0b8;
    border: 1px solid transparent;
    border-radius: 999px;
    padding: 6px 12px;
    font-size: 12px;
}

.run-mode-button:hover {
    background: #1b2432;
}

.run-mode-button.is-active {
    background: #f4efe5;
    color: #111;
    border-color: #f4efe5;
}

.example-tab {
    flex: 0 0 auto;
    background: #1a2230;
    color: #b8c7da;
    border: 1px solid #2e3a4d;
    border-radius: 999px;
    padding: 6px 12px;
    font-family: monospace;
    font-size: 12px;
}

.example-tab:hover {
    background: #243145;
}

.example-tab.is-active {
    background: #f4efe5;
    color: #111;
    border-color: #f4efe5;
}

.editor-shell {
    display: grid;
    grid-template-columns: 56px 1fr;
    flex: 1 1 auto;
    min-height: 220px;
    overflow: hidden;
    background: #0f1115;
}

.editor-gutter {
    overflow: hidden;
    padding: 12px 8px 12px 0;
    border-right: 1px solid #2a2f3a;
    background: #0b0d11;
    color: #5f6b7a;
    text-align: right;
    user-select: none;
}

.editor-line-number {
    display: block;
    font-size: 14px;
    line-height: 1.5;
}

.editor-stage {
    position: relative;
    overflow: hidden;
}

.editor-highlight,
.editor textarea {
    position: absolute;
    inset: 0;
    margin: 0;
    padding: 12px;
    border: none;
    outline: none;
    font-family: monospace;
    font-size: 14px;
    line-height: 1.5;
    tab-size: 4;
    white-space: pre;
    overflow: auto;
}

.editor-highlight {
    color: #e6e6e6;
    pointer-events: none;
    z-index: 1;
}

.editor textarea {
    flex: 1 1 auto;
    background: transparent;
    color: transparent;
    caret-color: #f4efe5;
    resize: none;
    z-index: 2;
    -webkit-text-fill-color: transparent;
}

.editor textarea::selection {
    background: rgba(76, 111, 166, 0.45);
}

.token-keyword {
    color: #ff7b72;
}

.token-type {
    color: #79c0ff;
}

.token-identifier {
    color: #e6edf3;
}

.token-string {
    color: #a5d6ff;
}

.token-number {
    color: #f2cc60;
}

.token-boolean {
    color: #ffa657;
}

.token-comment {
    color: #6e7681;
    font-style: italic;
}

.token-annotation {
    color: #d2a8ff;
}

.token-operator,
.token-punctuation {
    color: #c9d1d9;
}

.token-vdom-delimiter {
    color: #7ee787;
}

.token-vdom-tag {
    color: #56d364;
}

.token-vdom-attr {
    color: #79c0ff;
}

.token-vdom-text {
    color: #c9d1d9;
}

.preview {
    flex: 0 0 var(--preview-height);
    min-height: 140px;
    background: #f4efe5;
    color: #111;
    overflow: auto;
    padding: 14px;
}

.preview-resize-handle {
    position: relative;
    flex: 0 0 14px;
    border-top: 1px solid #2a2f3a;
    border-bottom: 1px solid #2a2f3a;
    background: linear-gradient(180deg, #171b23 0%, #12161d 100%);
    cursor: row-resize;
}

.preview-resize-handle::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 72px;
    height: 4px;
    border-radius: 999px;
    background: linear-gradient(90deg, #5f6b7a 0%, #9fb2c8 50%, #5f6b7a 100%);
    transform: translate(-50%, -50%);
    opacity: 0.9;
}

.preview-resize-handle:hover::before,
.preview-resize-handle:focus-visible::before,
.editor.is-resizing .preview-resize-handle::before {
    background: linear-gradient(90deg, #8eb8ff 0%, #f4efe5 50%, #8eb8ff 100%);
}

.preview-resize-handle:focus-visible {
    outline: 2px solid #8eb8ff;
    outline-offset: -2px;
}

.editor.is-resizing {
    user-select: none;
}

.preview-header {
    margin: 0 0 10px 0;
    font-size: 12px;
    color: #5f5a52;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

#preview {
    min-height: 160px;
}

.preview-empty {
    color: #7a6d5b;
    font-style: italic;
}

#preview .box {
    padding: 14px 16px;
    border: 1px solid #d7cab3;
    border-radius: 10px;
    background: #fffaf0;
    cursor: pointer;
}

#preview button {
    background: #1f5bd8;
    border-radius: 8px;
    padding: 8px 14px;
}

#preview h1,
#preview h2,
#preview h3,
#preview p,
#preview b,
#preview div {
    font-family: Georgia, "Times New Roman", serif;
}

.output {
    display: flex;
    flex-direction: column;
    min-height: 0;
}

.panel {
    flex: 1 1 0;
    padding: 10px;
    overflow: auto;
    min-height: 0;
}

.panel-resize-handle {
    position: relative;
    flex: 0 0 14px;
    border-top: 1px solid #2a2f3a;
    border-bottom: 1px solid #2a2f3a;
    background: linear-gradient(180deg, #171b23 0%, #12161d 100%);
    cursor: row-resize;
}

.panel-resize-handle::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 72px;
    height: 4px;
    border-radius: 999px;
    background: linear-gradient(90deg, #5f6b7a 0%, #9fb2c8 50%, #5f6b7a 100%);
    transform: translate(-50%, -50%);
    opacity: 0.9;
}

.panel-resize-handle:hover::before,
.panel-resize-handle:focus-visible::before,
.output.is-resizing .panel-resize-handle::before {
    background: linear-gradient(90deg, #8eb8ff 0%, #f4efe5 50%, #8eb8ff 100%);
}

.panel-resize-handle:focus-visible {
    outline: 2px solid #8eb8ff;
    outline-offset: -2px;
}

.output.is-resizing {
    user-select: none;
}

.panel h2 {
    margin: 0 0 6px 0;
    font-size: 12px;
    opacity: 0.6;
}

.stdout {
    white-space: pre-wrap;
    color: #c6f68d;
}

.stderr {
    white-space: pre-wrap;
    color: #ff6b6b;
}

#ast {
    font-size: 13px;
    line-height: 1.45;
}

.ast-node {
    position: relative;
}

.ast-row {
    display: flex;
    align-items: center;
    gap: 6px;
    min-height: 22px;
    padding: 1px 6px 1px 4px;
    border-radius: 4px;
    user-select: none;
}

.ast-row:hover {
    background: #171c26;
}

.ast-toggle {
    width: 12px;
    color: #7f8ea3;
    cursor: pointer;
    flex: 0 0 12px;
    text-align: center;
}

.ast-toggle.is-leaf {
    visibility: hidden;
    cursor: default;
}

.ast-label {
    color: #9cdcfe;
}

.ast-children {
    margin-left: 12px;
    padding-left: 12px;
    border-left: 1px solid #2a2f3a;
    display: none;
}

.ast-children.is-open {
    display: block;
}

.ast-meta {
    color: #7f8ea3;
}

@media (max-width: 960px) {
    main {
        grid-template-columns: 1fr;
        grid-template-rows: minmax(0, 1fr) minmax(260px, 40vh);
    }

    .editor {
        border-right: none;
        border-bottom: 1px solid #2a2f3a;
    }

    .example-tabs {
        padding: 8px 12px;
        align-items: flex-start;
        flex-direction: column;
    }

    .run-mode-toggle {
        margin-left: 0;
    }
}