body {
    display: flex;
    justify-content: center;
    padding: 2rem;
    background: var(--bg);
    transition: background 0.3s, color 0.3s;
}

.markdown-body {
    max-width: 900px;
    padding: 2rem;
    background: var(--content-bg);
    color: var(--text-color);
    border-radius: 6px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
    transition: background 0.3s, color 0.3s;
}

button {
    position: fixed;
    top: 1rem;
    right: 1rem;
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 14px;
    background-color: var(--btn-color);
}

:root {
    --pb-color : #cc2c00;
    --bg: #f6f8fa;  
    --content-bg: #ffffff;
    --text-color: #24292e;
    --btn-color : #24292e;
    --link-color : blue;
}

.dark {
    --pb-color : #007acc;
    --bg: #0d1117;
    --content-bg: #161b22;
    --text-color: #c9d1d9;
    --btn-color : #5f90f9;
    --link-color : #8d93fc;
}

/* ----------- */
/* Reading progress bar */
#progress-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: rgba(0,0,0,0.1);
    z-index: 1000;
}
#progress-bar {
    height: 100%;
    width: 0;
    background: var(--pb-color) ;
    transition: width 0.1s ease-out;
}

details > summary {
    font-size: 0.8em;
    color: var(--link-color) ;
}