/* Custom styles and overrides */
:root {
    --bg-light: #ffffff;
    --text-light: #1f2937;
    --sidebar-bg-light: #f9fafb;
    --border-light: #e5e7eb;
    --accent-light: #3b82f6;
    --code-bg-light: #f3f4f6;
    --code-text-light: #111827;

    --bg-dark: #111827;
    --text-dark: #d1d5db;
    --sidebar-bg-dark: #1f2937;
    --border-dark: #374151;
    --accent-dark: #60a5fa;
    --code-bg-dark: #1f2937;
    --code-text-dark: #e5e7eb;
}

/* Light mode variables */
html {
    --bg-color: var(--bg-light);
    --text-color: var(--text-light);
    --sidebar-bg-color: var(--sidebar-bg-light);
    --border-color: var(--border-light);
    --accent-color: var(--accent-light);
    --code-bg-color: var(--code-bg-light);
    --code-text-color: var(--code-text-light);
}

/* Dark mode variables */
html.dark {
    --bg-color: var(--bg-dark);
    --text-color: var(--text-dark);
    --sidebar-bg-color: var(--sidebar-bg-dark);
    --border-color: var(--border-dark);
    --accent-color: var(--accent-dark);
    --code-bg-color: var(--code-bg-dark);
    --code-text-color: var(--code-text-dark);
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
}

h1, h2, h3, h4 {
    font-weight: 700;
    color: var(--text-color);
}

a {
    color: var(--accent-color);
    transition: color 0.2s;
}
a:hover {
    text-decoration: underline;
}

/* Top Bar */
#top-bar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 3.5rem; /* 56px */
    background-color: var(--sidebar-bg-color);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 1rem;
    z-index: 50;
    transition: background-color 0.3s, border-color 0.3s;
}

/* Page Container to offset for fixed top bar */
#page-container {
    padding-top: 3.5rem;
}

#sidebar {
    background-color: var(--sidebar-bg-color);
    border-right: 1px solid var(--border-color);
    transition: background-color 0.3s, border-color 0.3s, transform 0.3s ease-in-out;
    position: fixed;
    top: 0;
    bottom: 0;
    padding-top: 4.5rem; /* Space for top bar */
    z-index: 40;
}

#main-content {
    transition: margin-left 0.3s ease-in-out;
    margin-left: 18rem; /* 288px, width of sidebar */
}

/* State for hidden sidebar */
body.sidebar-hidden #sidebar {
    transform: translateX(-100%);
}
body.sidebar-hidden #main-content {
    margin-left: 0;
}
@media (max-width: 768px) {
    #sidebar {
        transform: translateX(-100%);
    }
    #main-content {
        margin-left: 0;
    }
    body.sidebar-hidden #sidebar {
        transform: translateX(0);
    }
}


#sidebar a.active {
    background-color: var(--accent-color);
    color: white;
}
html.dark #sidebar a.active {
    color: var(--bg-dark);
}

pre[class*="language-"] {
    background-color: var(--code-bg-color) !important;
    color: var(--code-text-color) !important;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-family: 'Fira Code', monospace;
    /* Ensure code blocks can scroll horizontally on mobile */
    overflow-x: auto;
    white-space: pre;
}
code[class*="language-"] {
    font-family: 'Fira Code', monospace;
}
:not(pre) > code[class*="language-"] {
     background-color: var(--code-bg-color);
     color: var(--accent-color);
     padding: 0.2em 0.4em;
     border-radius: 0.3em;
}

/* Arrow Navigation */
.nav-arrow {
    position: fixed;
    top: 50%;
    transform: translateY(-50%);
    z-index: 30;
    background-color: var(--sidebar-bg-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-radius: 9999px;
    width: 3rem;
    height: 3rem;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    transition: all 0.2s ease-in-out, left 0.3s ease-in-out;
}
.nav-arrow:hover {
    background-color: var(--accent-color);
    color: white;
    border-color: var(--accent-color);
    text-decoration: none;
}
#prev-chapter-arrow {
    left: calc(18rem + 1rem); /* sidebar width (18rem) + padding (1rem) */
}
body.sidebar-hidden #prev-chapter-arrow {
    left: 1rem;
}
#next-chapter-arrow { right: 1rem; }
.nav-arrow.hidden { display: none; }

/* Hide floating arrows on tablets and smaller screens, replaced by bottom nav */
@media (max-width: 1280px) {
    .nav-arrow { display: none !important; }
}

/* Bottom chapter navigation */
.chapter-nav-link {
    display: block;
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    max-width: 48%;
}
.chapter-nav-link:hover {
    border-color: var(--accent-color);
    text-decoration: none;
}


/* Quiz Modal */
#quiz-modal {
    background-color: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(5px);
    z-index: 100;
}
#quiz-container {
    background-color: var(--bg-color);
    color: var(--text-color);
}
#quiz-footer {
    border-top: 1px solid var(--border-color);
    padding-top: 1rem;
}
.quiz-option.selected {
    border-color: var(--accent-color);
    background-color: color-mix(in srgb, var(--accent-color) 15%, transparent);
}
.quiz-option.correct {
    border-color: #22c55e;
    background-color: rgba(34, 197, 94, 0.1);
}
.quiz-option.incorrect {
    border-color: #ef4444;
    background-color: rgba(239, 68, 68, 0.1);
}

/* MODIFIED: Styles for "Why fullscreen?" link and text for responsiveness */
#why-fullscreen-container {
    position: absolute;
    bottom: -3rem;
    right: 0;
    text-align: right;
}
#why-fullscreen-link {
    font-size: 0.875rem;
    color: #9ca3af; /* gray-400 */
    text-decoration: underline;
    cursor: pointer;
}
html.dark #why-fullscreen-link {
    color: #6b7280; /* gray-500 */
}
#why-fullscreen-text {
    position: absolute;
    bottom: 2rem;
    right: 0;
    /* MODIFIED: Make width responsive */
    width: 90vw;
    max-width: 280px; 
    background-color: var(--sidebar-bg-dark);
    color: var(--text-dark);
    padding: 0.75rem;
    border-radius: 0.5rem;
    font-size: 0.875rem;
    box-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

details > summary {
    cursor: pointer;
    color: var(--accent-color);
    display: inline-block;
    margin-top: 1rem;
    font-weight: 500;
}
details > div {
    margin-top: 0.5rem;
    padding: 1rem;
    border-left: 4px solid var(--border-color);
    background-color: color-mix(in srgb, var(--accent-color) 5%, transparent);
    border-radius: 0 0.5rem 0.5rem 0;
}

/* Flowchart Styles */
.flowchart { font-family: 'Fira Code', monospace; font-size: 0.875rem; text-align: center; }
.flow-node { border: 2px solid var(--border-color); background-color: var(--code-bg-color); padding: 0.5rem 1rem; border-radius: 0.375rem; display: inline-block; margin: 0 auto; }
.flow-decision { transform: skew(-20deg); border-color: var(--accent-color); }
.flow-decision > span { display: inline-block; transform: skew(20deg); }
.flow-arrow { width: 2px; background-color: var(--border-color); height: 2rem; margin: 0 auto; position: relative; }
.flow-arrow::after { content: ''; position: absolute; bottom: 0; left: 50%; transform: translateX(-50%); border-left: 6px solid transparent; border-right: 6px solid transparent; border-top: 6px solid var(--border-color); }
.flow-branch { display: flex; justify-content: center; align-items: flex-start; }
.flow-path { display: flex; flex-direction: column; align-items: center; width: 50%; position: relative; }
.flow-path::before { content: ''; position: absolute; top: 0; height: 2px; width: calc(50% + 1rem); background-color: var(--border-color); }
.flow-path:first-child::before { left: 50%; }
.flow-path:last-child::before { right: 50%; }
.flow-path-label { position: absolute; top: 4px; background-color: var(--bg-color); padding: 0 0.25rem; color: var(--text-color); }
.flow-path:first-child .flow-path-label { left: 75%; }
.flow-path:last-child .flow-path-label { right: 75%; }
.flow-join { width: 100%; height: 2rem; border-bottom: 2px solid var(--border-color); border-left: 2px solid var(--border-color); border-right: 2px solid var(--border-color); border-bottom-left-radius: 0.5rem; border-bottom-right-radius: 0.5rem; }