:root {
    /* Colors */
    --background: #1c1f26;
    --background-secondary: #14161c;
    --background-tertiary: #181b22;
    --border: #2e3340;
    --text-primary: #cdd3de;
    --text-secondary: #7c8db5;
    --text-tertiary: #4a5370;
    --color-blue: #3d8ef0;
    --color-green: #34c98b;
    --color-error: #f07070;
    --color-white: #fff;

    /* Spacing */
    --space-xs: 0.3rem;
    --space-sm: 0.35rem;
    --space-md: 0.5rem;
    --space-lg: 0.75rem;
    --space-xl: 1rem;

    /* Other */
    --radius: 4px;
    --transition: 0.15s;
}

body {
    display: flex;
    flex-direction: column;
    height: 100vh;
    background: var(--background);
    color: var(--text-primary);
    font-family: 'Segoe UI', sans-serif;
    overflow: hidden;
}

/* ── Toolbar ── */
#toolbar {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-md) var(--space-xl);
    background: var(--background-secondary);
    border-bottom: 1px solid var(--border);
    flex-shrink: 0;
}

#toolbar h1 {
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    margin-right: auto;
}

button {
    padding: var(--space-sm) var(--space-xl);
    font-size: 0.8rem;
    font-family: inherit;
    font-weight: 600;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    transition: opacity var(--transition);
}

button:hover {
    opacity: 0.85;
}

#btn-j2y {
    background: var(--color-blue);
    color: var(--color-white);
}

#btn-y2j {
    background: var(--color-green);
    color: var(--color-white);
}

#error {
    font-size: 0.75rem;
    color: var(--color-error);
    margin-left: var(--space-md);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 50%;
}

/* ── Split panes ── */
#panes {
    display: flex;
    flex: 1;
    overflow: hidden;
}

.pane {
    display: flex;
    flex-direction: column;
    flex: 1;
    overflow: hidden;
}

.pane+.pane {
    border-left: 2px solid var(--border);
}

.pane-label {
    padding: var(--space-xs) var(--space-lg);
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    background: var(--background-tertiary);
    color: var(--text-tertiary);
    border-bottom: 1px solid var(--border);
    flex-shrink: 0;
}

.CodeMirror {
    height: 100% !important;
    font-size: 13px;
    line-height: 1.6;
    background: var(--background) !important;
}

.cm-wrap {
    flex: 1;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.cm-wrap .CodeMirror {
    flex: 1;
}

.CodeMirror-scroll {
    height: 100%;
}