:root {
    --text-color: #000;
    --bg-color: #C0C0C0; /* Classic Silver */
    --header-bg: #D3D3D3;
    --priority-high: #ffdddd;
    --priority-medium: #ffefdd;
    --priority-low: #ffffdd;
    --summary-hover: #B0B0B0;
    --link-color: #0000EE; /* Classic HTML Blue */
    --container-width: 800px;
    --border-radius: 0px; /* Sharp edges for retro look */
}

@media (prefers-color-scheme: dark) {
    :root {
        --text-color: #e0e0e0;
        --bg-color: #222;
        --header-bg: #333;
        --priority-high: #660000;
        --priority-medium: #664400;
        --priority-low: #666600;
        --summary-hover: #444;
        --link-color: #6699ff;
    }
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: "Verdana", "Tahoma", "Geneva", sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 1rem;
}

main {
    max-width: var(--container-width);
    margin: 0 auto;
}

h1 {
    text-align: center;
    border-bottom: 3px double var(--text-color);
    padding-bottom: 0.5rem;
}

h2 {
    border-bottom: 1px solid var(--text-color);
}

a {
    color: var(--link-color);
    text-decoration: underline;
}

.toc {
    background-color: var(--header-bg);
    padding: 1rem;
    border: 2px outset #fff;
    margin-bottom: 2rem;
}

.section {
    margin-bottom: 2rem;
}

details {
    margin-bottom: 1rem;
}

summary {
    padding: 1rem;
    background-color: var(--header-bg);
    cursor: pointer;
    font-weight: bold;
    border: 2px outset #fff;
}

summary:hover {
    background-color: var(--summary-hover);
}

details > div {
    padding: 1rem;
    background-color: var(--bg-color);
    border: 2px inset #fff;
    border-top: none;
}

.priority-indicator {
    display: inline-block;
    width: 15px;
    height: 15px;
    border: 1px solid #000;
    margin-right: 10px;
}

.priority-high { background-color: var(--priority-high); }
.priority-medium { background-color: var(--priority-medium); }
.priority-low { background-color: var(--priority-low); }

.font-controls {
    display: flex;
    justify-content: flex-end;
    margin-bottom: 1rem;
}

.font-controls button {
    background-color: var(--header-bg);
    border: 2px outset #fff;
    padding: 0.5rem;
    margin-left: 0.5rem;
    cursor: pointer;
}

.font-size-small { font-size: 0.9rem; }
.font-size-medium { font-size: 1rem; }
.font-size-large { font-size: 1.2rem; }

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}

footer {
    margin-top: 2rem;
    padding-top: 1rem;
    border-top: 1px solid var(--text-color);
    text-align: center;
}