:root {
    --primary: #3B82F6;
    --accent: #8B5CF6;
    --str: #16A34A;
    --num: #2563EB;
    --bool: #D97706;
    --null: #DC2626;
    --key: #7C3AED;
    --error: #DC2626;
    --error-bg: rgba(220,38,38,0.08);
    --bg: #FAFBFE;
    --card: #FFFFFF;
    --text: #1E293B;
    --text-sec: #64748B;
    --text-dim: #94A3B8;
    --border: #E2E8F0;
    --gutter: #F1F5F9;
    --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans', Helvetica, Arial, sans-serif;
    --mono: ui-monospace, SFMono-Regular, 'SF Mono', Menlo, Consolas, 'Liberation Mono', monospace;
    --radius: 10px;
    --transition: 0.15s ease;
    --font-size: 13px;
    --line-height: 1.7;
}
[data-theme="dark"] {
    --str: #4ADE80; --num: #60A5FA; --bool: #FBBF24; --null: #F87171; --key: #A78BFA;
    --error-bg: rgba(220,38,38,0.15);
    --bg: #0F1117; --card: #1A1D2E; --text: #E2E8F0; --text-sec: #94A3B8;
    --text-dim: #64748B; --border: #2D3348; --gutter: #141728;
}
*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
body{font-family:var(--font);background:var(--bg);color:var(--text);min-height:100vh;transition:background var(--transition),color var(--transition)}

/* Header */
.header{position:sticky;top:0;z-index:100;background:var(--card);border-bottom:1px solid var(--border)}
.header-inner{max-width:1600px;margin:0 auto;padding:10px 20px;display:flex;align-items:center;flex-wrap:wrap;gap:10px}
.logo{display:flex;align-items:center;gap:8px;flex-shrink:0;text-decoration:none}
.logo-text{font-size:1.15rem;font-weight:700;color:var(--text)}
.logo-dot{color:var(--primary)}
.btn-sm{padding:5px 12px;font-size:0.75rem;font-family:var(--font);font-weight:500;border:1px solid var(--border);border-radius:6px;background:var(--card);color:var(--text-sec);cursor:pointer;transition:all var(--transition)}
.btn-sm:hover{border-color:var(--primary);color:var(--primary)}
.btn-xs{padding:2px 8px;font-size:0.65rem;font-family:var(--font);font-weight:500;border:1px solid var(--border);border-radius:4px;background:var(--card);color:var(--text-sec);cursor:pointer;transition:all var(--transition)}
.btn-xs:hover{border-color:var(--primary);color:var(--primary)}
.btn-icon{width:34px;height:34px;border:1px solid var(--border);border-radius:6px;background:var(--card);color:var(--text-sec);cursor:pointer;display:flex;align-items:center;justify-content:center;transition:all var(--transition)}
.btn-icon:hover{border-color:var(--primary);color:var(--primary)}

/* Menu */
.menu-wrapper{position:relative;margin-left:auto;flex-shrink:0}
.menu-dropdown{display:none;position:absolute;top:calc(100% + 8px);right:0;min-width:180px;padding:6px 0;background:var(--card);border:1px solid var(--border);border-radius:var(--radius);box-shadow:0 12px 32px rgba(0,0,0,0.12);z-index:200}
[data-theme="dark"] .menu-dropdown{box-shadow:0 12px 32px rgba(0,0,0,0.4)}
.menu-dropdown.open{display:block}
.menu-item{display:block;padding:10px 16px;font-size:0.85rem;font-weight:500;color:var(--text);text-decoration:none;transition:background var(--transition);border:none;background:none;width:100%;text-align:left;cursor:pointer;font-family:var(--font)}
.menu-item:hover{background:var(--gutter);color:var(--primary)}

/* Main */
.main{max-width:1600px;margin:0 auto;padding:12px 20px}

/* App Layout with Sidebar */
.app-layout{display:flex;min-height:calc(100vh - 70px);position:relative}
.sidebar{width:240px;flex-shrink:0;background:var(--card);border-right:1px solid var(--border);display:flex;flex-direction:column;padding:12px;overflow-y:auto;transition:transform 0.2s ease,opacity 0.2s ease}
.sidebar.collapsed{transform:translateX(-100%);opacity:0;position:absolute;pointer-events:none}
.sidebar-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:10px}
.sidebar-header h3{font-size:0.82rem;font-weight:700}
.sidebar-list{flex:1;overflow-y:auto;display:flex;flex-direction:column;gap:6px}
.sidebar-save{margin-top:8px;width:100%;text-align:center;padding:6px}
.sidebar-toggle{position:absolute;left:240px;top:10px;z-index:60;width:26px;height:26px;border:1px solid var(--border);border-radius:6px;background:var(--card);color:var(--text-sec);cursor:pointer;display:flex;align-items:center;justify-content:center;transition:all var(--transition)}
.sidebar.collapsed ~ .sidebar-toggle{left:6px}
.sidebar-toggle:hover{border-color:var(--primary);color:var(--primary)}
.main-content{flex:1;padding:12px 20px 12px 40px;overflow-y:auto;overflow-x:hidden}

/* Hero */
.hero{text-align:center;padding:16px 0 12px}
.hero h1{font-size:1.7rem;font-weight:800;letter-spacing:-0.03em;line-height:1.2}
.gradient-text{background:linear-gradient(135deg,var(--primary),var(--accent));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.hero p{color:var(--text-sec);font-size:1rem;margin-top:6px}
.history-empty{color:var(--text-dim);font-size:0.78rem;text-align:center;padding:16px 0}
.history-item{padding:8px 10px;border:1px solid var(--border);border-radius:6px;cursor:pointer;transition:all var(--transition);font-size:0.72rem}
.history-item:hover{border-color:var(--primary);background:var(--gutter)}
.history-item-time{font-size:0.65rem;color:var(--text-dim)}
.history-item-preview{font-family:var(--mono);color:var(--text-sec);white-space:nowrap;overflow:hidden;text-overflow:ellipsis;max-width:200px;margin-top:2px}
.history-item-actions{margin-top:4px;text-align:right}
.history-item-actions .btn-xs{font-size:0.6rem}

/* Status Bar */
.status-bar{display:flex;align-items:center;flex-wrap:wrap;gap:8px;padding:8px 14px;margin-bottom:10px;background:var(--card);border:1px solid var(--border);border-radius:var(--radius);font-size:0.78rem}
.stats-divider{width:1px;height:16px;background:var(--border)}
.btn-primary{background:var(--primary);color:#fff;border-color:var(--primary)}
.btn-primary:hover{background:#2563EB;color:#fff}
.indent-select{padding:3px 6px;border:1px solid var(--border);border-radius:4px;background:var(--card);color:var(--text);font-size:0.72rem;font-family:var(--font)}
.status-valid{font-weight:600;color:var(--str)}
.status-valid.error{color:var(--error)}
.status-info{color:var(--text-dim);font-family:var(--mono)}
.indent-selector{display:flex;align-items:center;gap:6px;color:var(--text-sec)}
.indent-selector select{padding:3px 8px;border:1px solid var(--border);border-radius:4px;background:var(--card);color:var(--text);font-size:0.75rem;font-family:var(--font)}
.view-toggle{display:flex;gap:2px;background:var(--gutter);border:1px solid var(--border);border-radius:6px;padding:2px;margin-left:auto}
.view-btn{padding:4px 12px;font-size:0.75rem;font-family:var(--font);font-weight:500;border:none;border-radius:4px;background:transparent;color:var(--text-sec);cursor:pointer;transition:all var(--transition)}
.view-btn.active{background:var(--card);color:var(--text);box-shadow:0 1px 3px rgba(0,0,0,0.08)}

/* Editor Layout */
.editor-layout{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-bottom:10px;min-height:500px}
.editor-pane{border:1px solid var(--border);border-radius:var(--radius);overflow:hidden;background:var(--card);display:flex;flex-direction:column}
.pane-label{padding:6px 14px;font-size:0.7rem;font-weight:600;text-transform:uppercase;letter-spacing:0.05em;color:var(--text-sec);background:var(--gutter);border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;min-height:32px}
.pane-info{font-size:0.68rem;color:var(--text-dim);text-transform:none;letter-spacing:0;font-weight:400}
.json-path{font-size:0.7rem;font-family:var(--mono);color:var(--accent);margin-left:auto;margin-right:8px}
.code-area{flex:1;display:flex;position:relative;overflow:hidden}
.line-nums{min-width:36px;padding:10px 6px;text-align:right;font-family:var(--mono);font-size:var(--font-size);line-height:var(--line-height);color:var(--text-dim);background:var(--gutter);border-right:1px solid var(--border);user-select:none;overflow:hidden;white-space:pre-wrap}
.code-input{flex:1;padding:10px 12px;border:none;outline:none;resize:none;font-family:var(--mono);font-size:var(--font-size);line-height:var(--line-height);color:var(--text);background:var(--card);tab-size:2;overflow:auto;white-space:pre;word-wrap:normal;scrollbar-width:thin}

/* Output Editor */
.output-editor{flex:1;padding:10px 12px;font-family:var(--mono);font-size:var(--font-size);line-height:var(--line-height);overflow:auto;white-space:pre;word-wrap:normal;scrollbar-width:thin}
.output-editor .json-key{color:var(--key)}
.output-editor .json-str{color:var(--str)}
.output-editor .json-num{color:var(--num)}
.output-editor .json-bool{color:var(--bool)}
.output-editor .json-null{color:var(--null)}
.output-editor .json-bracket{color:var(--text-dim)}
.output-editor .json-error-line{background:var(--error-bg);display:block;border-left:3px solid var(--error);padding-left:8px;margin-left:-12px}

/* Tree View */
.tree-view{flex:1;padding:10px 16px;overflow:auto;font-family:var(--mono);font-size:var(--font-size);line-height:1.9}
.tree-node{padding-left:20px;position:relative}
.tree-toggle{cursor:pointer;user-select:none;color:var(--text-dim);display:inline-block;width:16px;text-align:center;margin-right:4px}
.tree-toggle:hover{color:var(--primary)}
.tree-key{color:var(--key);font-weight:500;cursor:pointer}
.tree-key:hover{text-decoration:underline}
.tree-str{color:var(--str)}
.tree-num{color:var(--num)}
.tree-bool{color:var(--bool)}
.tree-null{color:var(--null);font-style:italic}
.tree-bracket{color:var(--text-dim);font-size:0.85em}
.tree-collapsed .tree-children{display:none}

/* URL Bar */
.url-bar{display:flex;gap:6px;margin-bottom:12px;padding:8px 14px;background:var(--card);border:1px solid var(--border);border-radius:var(--radius)}
.url-input{flex:1;padding:6px 10px;border:1px solid var(--border);border-radius:6px;font-family:var(--mono);font-size:0.8rem;color:var(--text);background:var(--bg);outline:none;transition:border-color var(--transition)}
.url-input:focus{border-color:var(--primary)}

/* Tools Navigation */
.tools-nav{display:flex;flex-wrap:wrap;gap:5px;align-items:center;flex:1;margin-left:20px}
.tool-link{padding:3px 8px;font-size:0.65rem;font-weight:500;border-radius:5px;color:var(--text-sec);text-decoration:none;transition:all var(--transition);border:1px solid var(--border);background:var(--card)}
.tool-link:hover{border-color:var(--primary);color:var(--primary)}
.tool-link.active{background:var(--primary);color:#fff;border-color:var(--primary)}

/* SEO */
.seo-content{margin-top:40px;padding:32px;background:var(--card);border:1px solid var(--border);border-radius:var(--radius)}
.seo-content h2{font-size:1.3rem;font-weight:700;margin:24px 0 8px}
.seo-content h2:first-child{margin-top:0}
.seo-content p{color:var(--text-sec);margin-bottom:12px;line-height:1.7;font-size:0.9rem}
.features-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:12px;margin:16px 0}
.feature-card{padding:16px;border:1px solid var(--border);border-radius:8px;transition:border-color var(--transition),transform var(--transition)}
.feature-card:hover{border-color:var(--primary);transform:translateY(-2px)}
.feature-card h3{font-size:0.9rem;margin-bottom:4px}
.feature-card p{font-size:0.8rem;margin:0}
.seo-steps{color:var(--text-sec);padding-left:24px;margin:16px 0;font-size:0.9rem;line-height:2}
details{border:1px solid var(--border);border-radius:8px;padding:10px 14px;margin-bottom:6px;transition:border-color var(--transition)}
details:hover{border-color:var(--primary)}
details summary{font-weight:600;cursor:pointer;font-size:0.9rem}
details p{margin-top:6px;margin-bottom:0}

/* Footer */
.footer{margin-top:40px;border-top:1px solid var(--border);background:var(--card);text-align:center;padding:16px;font-size:0.8rem;color:var(--text-sec)}
.footer a{color:var(--text-sec);text-decoration:none}
.footer a:hover{color:var(--primary)}
.footer p{margin-top:6px;font-size:0.7rem;color:var(--text-dim)}

/* Toast */
.toast{position:fixed;bottom:20px;left:50%;transform:translateX(-50%) translateY(80px);padding:10px 20px;background:var(--text);color:var(--bg);border-radius:8px;font-size:0.82rem;font-weight:500;transition:transform 0.3s ease;z-index:1000;pointer-events:none}
.toast.show{transform:translateX(-50%) translateY(0)}

/* Shortcuts Dialog */
.shortcuts-overlay{display:none;position:fixed;top:0;left:0;right:0;bottom:0;background:rgba(0,0,0,0.4);z-index:1000;align-items:center;justify-content:center}
.shortcuts-overlay.open{display:flex}
.shortcuts-dialog{background:var(--card);border:1px solid var(--border);border-radius:12px;padding:24px;min-width:320px;box-shadow:0 20px 60px rgba(0,0,0,0.15)}
.shortcuts-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px}
.shortcuts-header h3{font-size:1rem;font-weight:700}
.shortcuts-list{display:flex;flex-direction:column;gap:10px}
.shortcut-row{display:flex;align-items:center;justify-content:space-between;font-size:0.85rem}
.shortcut-row kbd{padding:3px 8px;background:var(--gutter);border:1px solid var(--border);border-radius:4px;font-family:var(--mono);font-size:0.75rem}
.shortcut-row span{color:var(--text-sec)}

/* Responsive */
@media(max-width:768px){
    .editor-layout{grid-template-columns:1fr;min-height:auto}
    .header-actions{gap:4px}
    .btn-sm{padding:4px 8px;font-size:0.7rem}
    .main{padding:10px 12px}
    .features-grid{grid-template-columns:1fr}
    .status-bar{gap:8px}
}