:root {
    --bg: #f4f5f7;
    --panel-bg: #ffffff;
    --border: #dfe2e8;
    --text: #1f2430;
    --text-muted: #6b7280;
    --accent: #4f5fe0;
    --accent-hover: #3f4dc2;
    --danger: #d64545;
    --danger-bg: #fdecec;
    --success: #1f8a4c;
    --success-bg: #eaf7ee;

    --code-bg: #1e1e2e;
    --code-text: #d4d4d4;
    --json-key: #7dd3fc;
    --json-string: #f3a267;
    --json-number: #a3d977;
    --json-boolean: #c586c0;
    --json-null: #9aa0ac;
    --json-punct: #9098a8;
    --json-index: #6a9955;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: "Segoe UI", Roboto, -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
}

.app-header {
    padding: 1.25rem 2rem 0.75rem;
}

.app-header h1 {
    margin: 0 0 0.25rem;
    font-size: 1.5rem;
}

.subtitle {
    margin: 0;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.app-body {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    padding: 0.5rem 2rem 1.5rem;
    align-items: start;
}

@media (max-width: 900px) {
    .app-body {
        grid-template-columns: 1fr;
    }
}

.panel {
    background: var(--panel-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    min-height: 520px;
}

.panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.6rem 1rem;
    border-bottom: 1px solid var(--border);
    font-weight: 600;
    font-size: 0.9rem;
}

.panel-actions {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    font-weight: 400;
}

.indent-label {
    color: var(--text-muted);
    font-size: 0.85rem;
}

#indentSize {
    padding: 0.25rem 0.4rem;
    border-radius: 6px;
    border: 1px solid var(--border);
    background: var(--panel-bg);
    color: var(--text);
}

#jsonInput {
    flex: 1;
    resize: none;
    border: none;
    outline: none;
    padding: 1rem;
    font-family: "Cascadia Code", Consolas, "Courier New", monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    min-height: 320px;
    color: var(--text);
    background: var(--panel-bg);
}

.toolbar {
    display: flex;
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    border-top: 1px solid var(--border);
    flex-wrap: wrap;
}

.btn {
    appearance: none;
    border: 1px solid var(--border);
    background: var(--panel-bg);
    color: var(--text);
    padding: 0.45rem 0.9rem;
    border-radius: 7px;
    font-size: 0.85rem;
    cursor: pointer;
    transition: background 0.15s ease, border-color 0.15s ease;
}

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

.btn-primary {
    background: var(--accent);
    border-color: var(--accent);
    color: #fff;
    font-weight: 600;
}

.btn-primary:hover {
    background: var(--accent-hover);
    border-color: var(--accent-hover);
}

.btn-ghost {
    background: transparent;
}

.btn-small {
    padding: 0.3rem 0.6rem;
    font-size: 0.8rem;
}

.status-bar {
    min-height: 2.1rem;
    padding: 0 1rem 0.75rem;
    font-size: 0.85rem;
}

.status-bar.error {
    color: var(--danger);
}

.status-bar.error .status-pill {
    background: var(--danger-bg);
    color: var(--danger);
}

.status-bar.success .status-pill {
    background: var(--success-bg);
    color: var(--success);
}

.status-pill {
    display: inline-block;
    padding: 0.2rem 0.6rem;
    border-radius: 999px;
    font-weight: 600;
}

.tabs {
    display: flex;
    gap: 0.25rem;
}

.tab {
    appearance: none;
    border: none;
    background: transparent;
    color: var(--text-muted);
    padding: 0.4rem 0.75rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 600;
}

.tab.active {
    background: var(--accent);
    color: #fff;
}

.tab-content {
    display: none;
    flex: 1;
    overflow: auto;
    background: var(--code-bg);
}

.tab-content.active {
    display: block;
}

.tree-output,
.text-output {
    padding: 1rem;
    margin: 0;
    color: var(--code-text);
    font-family: "Cascadia Code", Consolas, "Courier New", monospace;
    font-size: 0.85rem;
    line-height: 1.6;
}

.text-output {
    white-space: pre;
    overflow: auto;
}

.empty-state {
    color: #7d8394;
    font-style: italic;
    font-family: "Segoe UI", Roboto, sans-serif;
}

.empty-state strong {
    color: #9aa4bb;
}

/* --- JSON syntax colors, shared between tree view and formatted text --- */
.json-key { color: var(--json-key); }
.json-string { color: var(--json-string); }
.json-number { color: var(--json-number); }
.json-boolean { color: var(--json-boolean); font-weight: 600; }
.json-null { color: var(--json-null); font-style: italic; }
.json-punctuation { color: var(--json-punct); }
.json-index { color: var(--json-index); }
.json-comma { color: var(--json-punct); }
.json-bracket { color: var(--code-text); font-weight: 600; }

/* --- Tree view structure --- */
.json-tree {
    white-space: normal;
}

.json-node {
    display: block;
    white-space: nowrap;
}

.json-node.json-leaf {
    padding-left: 0;
}

.json-children {
    margin-left: 0.95rem;
    padding-left: 0.6rem;
    border-left: 1px dotted #3c3f4d;
}

.json-toggle,
.json-toggle-spacer {
    display: inline-block;
    width: 1.1em;
    text-align: center;
}

.json-toggle {
    cursor: pointer;
    user-select: none;
    color: #7d8394;
}

.json-toggle::before {
    content: "\25BE"; /* ▾ */
}

.json-node.collapsed > .json-toggle::before {
    content: "\25B8"; /* ▸ */
}

.json-summary {
    display: none;
    color: #7d8394;
    font-style: italic;
    margin: 0 0.35em;
}

.json-node.collapsed > .json-summary {
    display: inline;
}

.json-node.collapsed > .json-summary::after {
    content: attr(data-close);
    color: var(--code-text);
    font-style: normal;
    margin-left: 0.35em;
}

.json-node.collapsed > .json-children,
.json-node.collapsed > .json-close {
    display: none;
}

.app-footer {
    padding: 1rem 2rem 2rem;
    color: var(--text-muted);
    font-size: 0.78rem;
    text-align: center;
}