/* --- Global Variables & Reset (Start of CSS) --- */
:root {
    /* Base Light Mode Palette */
    --primary-color: #3498db; /* Blue */
    --secondary-color: #2ecc71; /* Green */
    --accent-color: #f1c40f; /* Yellow */
    --background-color: #ecf0f1; /* Light Grey */
    --text-color: #2c3e50; /* Dark Navy */
    --card-background: #ffffff;
    --sidebar-background: #e4e6e9;
    --code-background: #f7f9fb;
    --border-color: #bdc3c7;
    --shadow-light: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-hover: 0 8px 20px rgba(0, 0, 0, 0.15);
}

/* Dark Mode Variables - Applied to body.dark-mode */
body.dark-mode {
    --primary-color: #9b59b6; /* Purple/Violet */
    --secondary-color: #1abc9c; /* Sea Green */
    --accent-color: #e67e22; /* Orange */
    --background-color: #2c3e50; /* Dark Navy */
    --text-color: #ecf0f1; /* Light Grey */
    --card-background: #34495e; /* Midnight Blue */
    --sidebar-background: #233140;
    --code-background: #2f4055;
    --border-color: #495d73;
    --shadow-light: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-hover: 0 8px 20px rgba(0, 0, 0, 0.6);
}

/* --- Base Styles --- */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Inter', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    background-color: var(--background-color);
    color: var(--text-color);
    transition: background-color 0.5s ease, color 0.5s ease;
    scroll-behavior: smooth;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s;
}

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

/* --- Header & Controls --- */
.header {
    background-color: var(--card-background);
    border-bottom: 3px solid var(--primary-color);
    padding: 20px 5%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.header .logo {
    font-size: 1.8em;
    font-weight: 700;
    color: var(--text-color);
    display: flex;
    align-items: center;
}

.header .logo i {
    color: var(--primary-color);
    margin-right: 10px;
    font-size: 1.2em;
}

.header-controls {
    display: flex;
    align-items: center;
    gap: 20px;
}

/* Progress Indicator Styling */
.progress-indicator {
    font-weight: bold;
    color: var(--primary-color);
    font-size: 0.9em;
    padding: 5px 10px;
    border: 1px solid var(--primary-color);
    border-radius: 5px;
}

#progress-percentage {
    color: var(--accent-color);
}

/* Dark Mode Toggle Button Styling */
.toggle-btn {
    background: var(--sidebar-background);
    border: none;
    color: var(--text-color);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.1em;
    display: flex;
    justify-content: center;
    align-items: center;
    box-shadow: var(--shadow-light);
    transition: all 0.3s;
}

.toggle-btn:hover {
    background-color: var(--primary-color);
    color: white;
    transform: rotate(30deg) scale(1.1);
}

/* Dark Mode Specific Icon Color */
body.dark-mode .toggle-btn i {
    color: var(--secondary-color);
}

body.dark-mode .toggle-btn:hover {
    background-color: var(--primary-color);
    color: white;
}

/* --- Main Layout: Sidebar + Content --- */
.main-container {
    display: flex;
    max-width: 1400px;
    margin: 30px auto;
    width: 95%;
    flex-grow: 1; /* Ensures content fills space above footer */
}

/* --- Sidebar Navigation --- */
.sidebar {
    width: 280px;
    flex-shrink: 0;
    padding: 20px;
    background-color: var(--sidebar-background);
    border-radius: 10px;
    box-shadow: var(--shadow-light);
    position: sticky;
    top: 100px; /* Aligns below the sticky header */
    height: fit-content;
    transition: background-color 0.5s;
}

.sidebar h3 {
    color: var(--primary-color);
    text-transform: uppercase;
    margin-bottom: 15px;
    font-size: 1.1em;
    letter-spacing: 1px;
    padding-bottom: 5px;
    border-bottom: 2px solid var(--border-color);
}

.course-nav ul {
    list-style: none;
}

.course-nav li {
    margin-bottom: 8px;
}

.course-nav a {
    display: block;
    padding: 10px 15px;
    border-radius: 5px;
    color: var(--text-color);
    font-weight: 500;
    transition: background-color 0.3s, color 0.3s;
    border-left: 3px solid transparent;
}

.course-nav a:hover {
    background-color: rgba(52, 152, 219, 0.1);
    color: var(--primary-color);
    text-decoration: none;
}

/* Active navigation link */
.course-nav a.active-link {
    background-color: var(--primary-color);
    color: white;
    font-weight: bold;
    border-left: 3px solid var(--accent-color);
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
}

.course-nav a.active-link:hover {
    color: white;
    background-color: var(--primary-color);
}

/* --- Main Content Area --- */
.content-area {
    flex-grow: 1;
    margin-left: 30px;
}

/* --- Course Section Styling (The Unique Card Design) --- */
.course-section {
    background-color: var(--card-background);
    padding: 40px;
    margin-bottom: 30px;
    border-radius: 12px;
    box-shadow: var(--shadow-light);
    border: 1px solid var(--border-color);
    transition: all 0.4s ease;
}

.course-section:hover {
    box-shadow: var(--shadow-hover);
    border-color: var(--primary-color);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 3px solid var(--secondary-color);
    padding-bottom: 15px;
    margin-bottom: 20px;
}

.section-header h2 {
    color: var(--primary-color);
    font-size: 2em;
    font-weight: 600;
}

/* Module Completion Checkbox */
.module-checkbox {
    width: 24px;
    height: 24px;
    cursor: pointer;
    accent-color: var(--secondary-color);
}

/* Explanation Text */
.explanation {
    margin-bottom: 25px;
    line-height: 1.8;
}

.explanation h3 {
    color: var(--secondary-color);
    margin-top: 25px;
    margin-bottom: 15px;
    font-size: 1.4em;
    border-left: 5px solid var(--accent-color);
    padding-left: 10px;
}

.explanation ul, .explanation ol {
    list-style-type: none;
    padding-left: 0;
    margin-top: 15px;
    margin-bottom: 20px;
}

.explanation li {
    padding-left: 25px;
    position: relative;
    margin-bottom: 10px;
}

.explanation li::before {
    content: "\f058"; /* Checkmark icon */
    font-family: 'Font Awesome 6 Free';
    font-weight: 900;
    color: var(--secondary-color);
    position: absolute;
    left: 0;
    top: 2px;
}

.key-concept {
    background-color: rgba(52, 152, 219, 0.1);
    color: var(--text-color);
    padding: 15px 20px;
    border-radius: 8px;
    font-style: italic;
    margin: 25px 0;
    display: block;
    border-left: 4px solid var(--primary-color);
}

.detailed-explanation {
    background-color: rgba(46, 204, 113, 0.1);
    padding: 20px;
    border-radius: 8px;
    margin: 25px 0;
    border: 1px solid var(--secondary-color);
}

.detailed-explanation h4 {
    color: var(--secondary-color);
    margin-bottom: 10px;
    font-size: 1.2em;
}

/* --- Code Block Styling (PrismJS Integration) --- */
.code-example {
    margin-top: 30px;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
}

.code-example h3 {
    background-color: var(--primary-color);
    color: white;
    padding: 12px 15px;
    margin-bottom: 0;
    font-size: 1.2em;
    border-bottom: 1px solid var(--accent-color);
}

/* PrismJS Customization */
pre[class*="language-"] {
    margin: 0 !important;
    padding: 20px !important;
    background-color: var(--code-background) !important;
    font-family: 'Fira Code', 'Consolas', 'Monaco', monospace;
    font-size: 0.95em;
    border: none;
    line-height: 1.5;
}

code {
    font-family: 'Fira Code', 'Consolas', 'Monaco', monospace;
    background-color: rgba(52, 152, 219, 0.1);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.95em;
    color: var(--primary-color);
}

body.dark-mode code {
    color: #81e6d9;
    background-color: rgba(129, 230, 217, 0.1);
}

/* Notes below code */
.notes {
    background-color: var(--accent-color);
    color: var(--text-color);
    padding: 12px 15px;
    margin: 0;
    border-bottom-left-radius: 8px;
    border-bottom-right-radius: 8px;
    font-size: 0.95em;
}
body.dark-mode .notes {
    color: #2c3e50;
}

/* Live Preview Box */
.live-preview {
    background-color: white;
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 25px;
    margin: 25px 0;
    min-height: 150px;
}

body.dark-mode .live-preview {
    background-color: #2d3748;
    border-color: var(--border-color);
}

.live-preview-title {
    color: var(--secondary-color);
    font-weight: 600;
    margin-bottom: 15px;
    font-size: 1.1em;
}

/* Mobile Progress Bar (Hidden on Desktop) */
.mobile-progress-bar {
    display: none;
    width: 100%;
    height: 10px;
    background-color: var(--border-color);
    border-radius: 5px;
    margin-bottom: 20px;
}
.mobile-progress-bar .bar-fill {
    height: 100%;
    width: 0%;
    background-color: var(--secondary-color);
    border-radius: 5px;
    transition: width 0.5s ease;
}


/* --- Footer --- */
.footer {
    text-align: center;
    padding: 25px;
    border-top: 2px solid var(--border-color);
    color: var(--text-color);
    opacity: 0.8;
    background-color: var(--card-background);
    margin-top: auto; /* Pushes footer to the bottom */
}


/* --- Media Queries (Responsiveness) --- */
@media (max-width: 1024px) {
    .main-container {
        flex-direction: column;
        width: 100%;
        margin: 20px auto;
    }

    .sidebar {
        width: 100%;
        position: static;
        margin-bottom: 30px;
    }

    .content-area {
        margin-left: 0;
        padding: 0 15px;
    }

    .progress-indicator {
        display: none; /* Hide desktop progress indicator */
    }

    .mobile-progress-bar {
        display: block; /* Show mobile progress bar */
    }
}

@media (max-width: 600px) {
    .header {
        padding: 15px 15px;
        flex-direction: column;
        gap: 10px;
    }

    .header .logo {
        font-size: 1.5em;
    }

    .section-header h2 {
        font-size: 1.5em;
    }

    .course-section {
        padding: 20px;
    }
}

/* Dark mode specific fixes */
body.dark-mode .explanation p,
body.dark-mode .explanation li,
body.dark-mode .footer,
body.dark-mode .sidebar h3,
body.dark-mode .course-nav a,
body.dark-mode .section-header h2,
body.dark-mode .code-example h3,
body.dark-mode .live-preview-title,
body.dark-mode .progress-indicator,
body.dark-mode .toggle-btn {
    color: var(--text-color) !important;
}

body.dark-mode .explanation h3 {
    color: var(--secondary-color) !important;
}

body.dark-mode .key-concept {
    color: var(--text-color) !important;
    background-color: rgba(155, 89, 182, 0.1);
    border-left-color: var(--primary-color);
}

body.dark-mode .detailed-explanation {
    background-color: rgba(26, 188, 156, 0.1);
    border-color: var(--secondary-color);
}

body.dark-mode {
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}
/* End of CSS file */