:root {
    --bg: #f4f7fb;
    --panel: rgba(255, 255, 255, 0.92);
    --panel-border: #d6dfeb;
    --text: #183247;
    --muted: #60758a;
    --primary: #1d6fd6;
    --primary-hover: #165db3;
    --success-bg: #edf9f1;
    --success-text: #1f7a41;
    --error-bg: #fff1f1;
    --error-text: #b23a3a;
    --shadow: 0 18px 55px rgba(22, 50, 84, 0.12);
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    color: var(--text);
    background:
        radial-gradient(circle at top left, rgba(29, 111, 214, 0.12), transparent 30%),
        radial-gradient(circle at bottom right, rgba(45, 164, 127, 0.12), transparent 25%),
        var(--bg);
}

.app-shell {
    width: min(1200px, calc(100% - 32px));
    margin: 32px auto;
}

.hero,
.toolbar,
.panel,
.message {
    backdrop-filter: blur(10px);
}

.hero {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    padding: 28px;
    border: 1px solid var(--panel-border);
    border-radius: 24px;
    background: var(--panel);
    box-shadow: var(--shadow);
}

.eyebrow {
    margin: 0 0 8px;
    color: var(--primary);
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.18em;
    text-transform: uppercase;
}

.hero h1 {
    margin: 0;
    font-size: clamp(30px, 4vw, 44px);
}

.subtitle {
    margin: 10px 0 0;
    color: var(--muted);
    font-size: 16px;
}

.hero-badge {
    flex-shrink: 0;
    display: grid;
    place-items: center;
    width: 112px;
    height: 112px;
    border-radius: 28px;
    background: linear-gradient(135deg, #1d6fd6, #3ea980);
    color: #fff;
    font-size: 28px;
    font-weight: 800;
    letter-spacing: 0.08em;
}

.toolbar {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 20px;
    padding: 18px;
    border: 1px solid var(--panel-border);
    border-radius: 20px;
    background: var(--panel);
    box-shadow: var(--shadow);
}

button {
    appearance: none;
    border: 1px solid #c7d6e6;
    border-radius: 14px;
    background: #fff;
    color: var(--text);
    padding: 12px 18px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease, border-color 0.18s ease;
}

button:hover {
    transform: translateY(-1px);
    box-shadow: 0 8px 22px rgba(22, 50, 84, 0.12);
    border-color: #acc6e4;
}

button.primary {
    background: var(--primary);
    border-color: var(--primary);
    color: #fff;
}

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

button.ghost.danger {
    color: var(--error-text);
    border-color: #f0c9c9;
    background: #fff8f8;
}

.workspace {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 20px;
    margin-top: 20px;
}

.panel {
    border: 1px solid var(--panel-border);
    border-radius: 24px;
    background: var(--panel);
    box-shadow: var(--shadow);
    padding: 20px;
}

.panel-head {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 14px;
}

.panel-head label {
    font-weight: 700;
    font-size: 18px;
}

.panel-head span {
    color: var(--muted);
    font-size: 14px;
}

.view-switch {
    display: flex;
    gap: 8px;
    align-items: center;
}

.tab-btn {
    padding: 8px 14px;
    border-radius: 999px;
    font-size: 13px;
}

.tab-btn.active {
    background: #eaf3ff;
    border-color: #a8c8ef;
    color: var(--primary);
    box-shadow: none;
}

.output-stage {
    position: relative;
}

.output-view,
.tree-output {
    min-height: 420px;
}

textarea {
    width: 100%;
    min-height: 420px;
    resize: vertical;
    border: 1px solid #ced9e5;
    border-radius: 18px;
    padding: 18px;
    background: #fbfdff;
    color: var(--text);
    font: 14px/1.7 "Consolas", "Courier New", monospace;
    overflow: auto;
    white-space: pre;
    tab-size: 4;
}

.tree-output {
    overflow: auto;
    border: 1px solid #ced9e5;
    border-radius: 18px;
    padding: 18px;
    background: #fbfdff;
    font: 14px/1.8 "Consolas", "Courier New", monospace;
    white-space: nowrap;
}

.tree-empty {
    color: var(--muted);
}

.json-tree,
.tree-children {
    margin: 0;
    padding: 0;
    list-style: none;
}

.tree-children {
    padding-left: 24px;
}

.tree-row {
    display: flex;
    align-items: flex-start;
    gap: 8px;
}

.tree-line {
    display: inline-flex;
    align-items: flex-start;
    gap: 6px;
    min-width: 0;
}

.tree-toggle {
    width: 22px;
    height: 22px;
    border-radius: 7px;
    border: 1px solid #8ed0ee;
    background: #f2fbff;
    color: #119bd7;
    font: inherit;
    font-weight: 700;
    padding: 0;
    line-height: 1;
    flex: 0 0 auto;
}

.tree-toggle:hover {
    box-shadow: none;
    transform: none;
    background: #dff5ff;
}

.tree-spacer {
    width: 22px;
    height: 22px;
    flex: 0 0 auto;
}

.tree-key {
    color: #8b2aa7;
    font-weight: 700;
}

.tree-string {
    color: #2fad49;
    font-weight: 700;
}

.tree-number {
    color: #2b9ad6;
    font-weight: 700;
}

.tree-boolean,
.tree-null {
    color: #ff7a7a;
    font-weight: 700;
}

.tree-punctuation,
.tree-bracket,
.tree-summary,
.tree-comma {
    color: #7d8b92;
}

.tree-summary {
    cursor: pointer;
}

.collapsed > .tree-row .tree-summary {
    color: #6c7b82;
}

textarea:focus {
    outline: 2px solid rgba(29, 111, 214, 0.18);
    border-color: #8cb7ea;
}

.message-stack {
    margin-top: 20px;
    display: grid;
    gap: 12px;
}

.message {
    padding: 16px 18px;
    border-radius: 18px;
    border: 1px solid var(--panel-border);
    background: var(--panel);
    box-shadow: var(--shadow);
    white-space: pre-wrap;
    line-height: 1.6;
}

.message.error {
    background: var(--error-bg);
    color: var(--error-text);
    border-color: #efc7c7;
}

.message.status {
    background: var(--success-bg);
    color: var(--success-text);
    border-color: #c9e8d3;
}

.hidden {
    display: none;
}

@media (max-width: 860px) {
    .hero {
        flex-direction: column;
        align-items: flex-start;
    }

    .hero-badge {
        width: 84px;
        height: 84px;
        border-radius: 22px;
        font-size: 22px;
    }

    .workspace {
        grid-template-columns: 1fr;
    }

    textarea,
    .tree-output {
        min-height: 300px;
    }
}

@media (max-width: 560px) {
    .app-shell {
        width: min(100% - 20px, 1200px);
        margin: 10px auto 24px;
    }

    .hero,
    .toolbar,
    .panel,
    .message {
        border-radius: 18px;
    }

    .toolbar {
        padding: 14px;
    }

    button {
        flex: 1 1 calc(50% - 12px);
    }

    .panel-head {
        align-items: flex-start;
        flex-direction: column;
    }
}