/* Basic page setup — keeps layout consistent across browsers and gives the page a calm background. */
*, *::before, *::after { box-sizing: border-box; }
body {
    font: 76%/1.4 arial, sans-serif;
    color: #012;
    margin: 0;
    background: #f7ffff;
    -webkit-font-smoothing: antialiased;
}

p {
    margin: 0 10px 10px;
}

a#link {
    background-color: #43d4d4;
    text-align: center;
    border-style: hidden;
    font-size: 25px;
}

div#header {
    background-color: #43d4d4;
    max-width: 1100px;
    margin: 0 auto;
    padding: 12px 16px;
}

div#header h1 {
    margin: 0;
    padding: 8px 0;
    font-size: 1.6rem;
    text-align: center;
}

div#header h2 {
    margin: 6px 0 0 0;
    padding: 4px 0 10px 0;
    font-size: 1.05rem;
    text-align: center;
}

div#container {
    text-align: left;
}

div#content p {
    display: list-item;
    line-height: 1.4;
    list-style-type:circle;
}

div#extra {
    background:#43d4d4;
    max-width: 1100px;
    margin: 16px auto;
    padding: 12px;
    clear: both;
}

div#footer {
    background: #43d4d4;
}

div#footer p {
    margin: 0;
    padding: 5px 10px
}

/* Main content container — centered and padded for comfortable reading on all screens. */
div#container {
    max-width: 900px;
    margin: 18px auto;
    background-color: #6affff;
    padding: 14px;
}

/* Content area — stretches to fit smaller screens, and participates in a gentle two-column layout on wide screens. */
div#content {
    width: 100%;
    margin: 0;
}

/* On larger displays, arrange content in two columns so the page feels balanced and readable. */
@media (min-width: 900px) {
    div#container { display: flex; gap: 20px; align-items: flex-start; }
    div#content { flex: 1 1 60%; }
}

/* Styles for the left sliding links panel and its small handle. This creates the visible handle, the sliding area, and the open/closed states. */
.folding-tab {
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    height: 100vh;
    z-index: 9999;
    width: 56px; /* collapsed width (visible handle) */
    transition: width 0.28s ease;
    background: transparent;
    overflow: visible;
}
.folding-tab .tab-toggle {
    display: block;
    width: 56px;
    height: 56px;
    margin: 12px 0 0 0;
    border: none;
    background: #43d4d4;
    color: #012;
    font-weight: 700;
    cursor: pointer;
    border-radius: 0 6px 6px 0;
    box-shadow: 0 2px 6px rgba(0,0,0,0.15);
}
.folding-tab .tab-panel {
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 320px; /* panel width when open */
    background: #6affff;
    padding-top: 16px;
    box-shadow: 2px 0 12px rgba(0,0,0,0.12);
    transform-origin: left center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.28s ease, transform 0.28s ease;
    transform: translateX(-8px) scaleX(0.98);
}
.folding-tab .tab-panel ul { list-style: none; margin: 12px; padding: 0; }
.folding-tab .tab-panel li { margin: 12px 0; }
.folding-tab .tab-panel a { color: #012; text-decoration: none; font-weight: 600; padding: 8px 12px; display: inline-block; }
.folding-tab.open {
    width: 320px;
}
.folding-tab.open .tab-panel {
    opacity: 1;
    pointer-events: auto;
    transform: translateX(0) scaleX(1);
}

/* When the panel opens, visually shift page content using transform so the layout width doesn't increase. */
body { -webkit-font-smoothing: antialiased; }

/* Apply the sliding transform to all top-level children except the folding tab itself. This avoids changing layout width (no horizontal scroll). */
body > *:not(.folding-tab) {
    transition: transform 0.28s ease;
}

/* When open, translate page content to the right by the panel width. */
body.tab-open > *:not(.folding-tab) {
    transform: translateX(320px);
}

/* Small-screen adjustments — tighter spacing and smaller panel width for phones. */
@media (max-width: 640px) {
    .folding-tab { width: 48px; }
    .folding-tab .tab-toggle { width: 48px; height: 48px; }
    .folding-tab .tab-panel { width: 220px; }
    /* Use transform on page content for small screens too, avoiding layout width changes */
    body.tab-open > *:not(.folding-tab) { transform: translateX(220px); }

    /* Make header text a bit smaller on small screens */
    div#header h1 { font-size: 1.25rem; }
    div#header { padding: 10px; }
    div#container { padding: 10px; margin: 12px; }
}

/* Assignment images: show side-by-side on wide screens and stack on small screens */
.assignment-images {
    /* Stack images vertically with comfortable spacing for readability */
    display: flex;
    flex-direction: column;
    gap: 20px;
    align-items: center;
    margin: 18px 0;
}
.assignment-figure {
    width: 100%;
    max-width: 880px; /* keep very wide images from overflowing */
    text-align: center;
}
.assignment-figure img {
    width: 100%;
    height: auto;
    display: block;
    border: 1px solid rgba(0,0,0,0.06);
    border-radius: 6px;
    box-shadow: 0 2px 6px rgba(0,0,0,0.06);
}
.assignment-figure figcaption {
    margin-top: 8px;
    font-size: 0.95rem;
    color: rgba(0,0,0,0.7);
}
@media (max-width: 640px) {
    .assignment-figure { padding: 0 6px; }
}

/* Ensure images placed directly inside .assignment-images (no figure) also scale to the page */
.assignment-images img {
    width: 100%;
    max-width: 880px;
    height: auto;
    display: block;
    margin: 0 auto;
    border: 1px solid rgba(0,0,0,0.06);
    border-radius: 6px;
    box-shadow: 0 2px 6px rgba(0,0,0,0.06);
}
.assignment-images p {
    width: 100%;
    max-width: 880px;
    margin: 6px auto 0 auto;
    padding: 0 6px;
}

/* Prevent extremely tall images from pushing the layout too far — scale to viewport height if necessary */
.assignment-images img { max-height: 80vh; object-fit: contain; }

@media (max-width: 640px) {
    .assignment-images img { max-height: 60vh; }
}