/* === Base Styles, Variables & Theming === */
:root {
    /* Light Theme (Default) */
    --bg-gradient-start: #667eea;
    --bg-gradient-end: #764ba2;
    --header-bg: rgba(26, 32, 44, 0.3); /* Darker semi-transparent */
    --header-border: rgba(255, 255, 255, 0.15);
    --header-text: #ffffff;
    --nav-link-text: #e5e7eb; /* gray-200 */
    --nav-link-hover-bg: rgba(255, 255, 255, 0.1);
    --nav-link-active-bg: rgba(99, 102, 241, 0.6); /* indigo-500 */
    --content-bg: rgba(255, 255, 255, 0.15);
    --content-border: rgba(255, 255, 255, 0.25);
    --content-shadow: rgba(31, 38, 135, 0.15);
    --content-text: #0f172a; /* slate-900 */
    --heading-text: #1e3a8a; /* blue-800 */
    --subheading-text: #1e40af; /* blue-700 */
    --section-border: rgba(55, 65, 81, 0.3);
    --link-text: #6d28d9; /* violet-700 */
    --link-hover-text: #4c1d95; /* violet-900 */
    --code-inline-bg: rgba(243, 232, 255, 0.5);
    --code-inline-text: #6b21a8; /* purple-800 */
    --code-inline-border: rgba(168, 85, 247, 0.2);
    --code-block-bg: rgba(243, 232, 255, 0.3);
    --code-block-border: rgba(168, 85, 247, 0.3);
    --code-block-text: #581c87; /* purple-900 */
    --button-cta-gradient-start: #8b5cf6; /* violet-500 */
    --button-cta-gradient-end: #7c3aed; /* violet-600 */
    --button-cta-hover-start: #7c3aed;
    --button-cta-hover-end: #6d28d9; /* violet-700 */
    --button-cta-shadow: rgba(124, 58, 237, 0.3);
    --important-note-bg: rgba(250, 245, 255, 0.6);
    --important-note-border: rgba(216, 180, 254, 0.5);
    --important-note-text: #581c87;
    --important-note-strong: #3b0764;
    --quiz-bg: rgba(250, 245, 255, 0.4);
    --quiz-border: rgba(168, 85, 247, 0.4);
    --quiz-legend-text: #4c1d95;
    --quiz-results-bg: rgba(245, 243, 255, 0.7);
    --quiz-results-border: rgba(196, 181, 253, 0.7);
    --footer-bg: rgba(17, 24, 39, 0.3);
    --footer-border: rgba(55, 65, 81, 0.3);
    --footer-text: #d1d5db; /* gray-300 */

    /* Syntax Highlighting (can be themed too if needed) */
    --syntax-html-tag: #1d4ed8;
    --syntax-html-attr: #c2410c;
    --syntax-html-value: #059669;
    --syntax-comment: #6d28d9;
    --syntax-css-selector: #9333ea;
    --syntax-css-property: #c2410c;
    --syntax-css-value: #059669;
    --syntax-js-keyword: #1d4ed8;
    --syntax-js-string: #059669;
    --syntax-js-number: #be185d;
    --syntax-js-function: #c2410c;
    --syntax-js-operator: #581c87;
}

body.dark-mode {
    /* Dark Theme */
    --bg-gradient-start: #1f2937; /* gray-800 */
    --bg-gradient-end: #111827; /* gray-900 */
    --header-bg: rgba(17, 24, 39, 0.5); /* gray-900 semi-transparent */
    --header-border: rgba(55, 65, 81, 0.5); /* gray-700 */
    --header-text: #f9fafb; /* gray-50 */
    --nav-link-text: #d1d5db; /* gray-300 */
    --nav-link-hover-bg: rgba(55, 65, 81, 0.5); /* gray-700 */
    --nav-link-active-bg: rgba(79, 70, 229, 0.7); /* indigo-600 */
    --content-bg: rgba(31, 41, 55, 0.25); /* gray-800 */
    --content-border: rgba(75, 85, 99, 0.4); /* gray-600 */
    --content-shadow: rgba(0, 0, 0, 0.2);
    --content-text: #d1d5db; /* gray-300 */
    --heading-text: #93c5fd; /* blue-300 */
    --subheading-text: #a5b4fc; /* indigo-300 */
    --section-border: rgba(107, 114, 128, 0.4); /* gray-500 */
    --link-text: #a78bfa; /* violet-400 */
    --link-hover-text: #c4b5fd; /* violet-300 */
    --code-inline-bg: rgba(55, 48, 163, 0.3); /* indigo-900 */
    --code-inline-text: #c4b5fd; /* violet-300 */
    --code-inline-border: rgba(129, 140, 248, 0.3); /* indigo-400 */
    --code-block-bg: rgba(30, 41, 59, 0.5); /* slate-800 */
    --code-block-border: rgba(51, 65, 85, 0.6); /* slate-700 */
    --code-block-text: #c7d2fe; /* indigo-200 */
    --button-cta-gradient-start: #a78bfa; /* violet-400 */
    --button-cta-gradient-end: #8b5cf6; /* violet-500 */
    --button-cta-hover-start: #8b5cf6;
    --button-cta-hover-end: #7c3aed; /* violet-600 */
    --button-cta-shadow: rgba(167, 139, 250, 0.2);
    --important-note-bg: rgba(79, 70, 229, 0.2); /* indigo-600 */
    --important-note-border: rgba(99, 102, 241, 0.4); /* indigo-500 */
    --important-note-text: #c7d2fe; /* indigo-200 */
    --important-note-strong: #e0e7ff; /* indigo-100 */
    --quiz-bg: rgba(55, 48, 163, 0.3); /* indigo-900 */
    --quiz-border: rgba(99, 102, 241, 0.4); /* indigo-500 */
    --quiz-legend-text: #a5b4fc; /* indigo-300 */
    --quiz-results-bg: rgba(30, 41, 59, 0.6); /* slate-800 */
    --quiz-results-border: rgba(51, 65, 85, 0.7); /* slate-700 */
    --footer-bg: rgba(0, 0, 0, 0.4);
    --footer-border: rgba(55, 65, 81, 0.5);
    --footer-text: #9ca3af; /* gray-400 */

    /* Dark mode Syntax Highlighting */
    --syntax-comment: #a5b4fc; /* indigo-300 */
    --syntax-js-variable: #e0e7ff; /* indigo-100 */
    --syntax-js-operator: #c4b5fd; /* violet-300 */
}


body {
    font-family: 'Inter', sans-serif;
    scroll-behavior: smooth;
    color: var(--content-text); /* Use variable */
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    min-height: 100vh;
    background-attachment: fixed;
    transition: background 0.3s ease; /* Smooth background transition */
}

/* === Container === */
.container {
    width: 90%;
    max-width: 1100px;
    margin-left: auto;
    margin-right: auto;
    padding-left: 1rem;
    padding-right: 1rem;
}

/* === Header === */
.sticky-header {
    position: sticky;
    top: 0;
    z-index: 50;
    padding: 0.5rem 0; /* Adjusted padding */
    background-color: var(--header-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--header-border);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.header-container {
    display: flex;
    flex-wrap: wrap; /* Allow wrap */
    align-items: center;
    justify-content: space-between;
    gap: 0.5rem 1rem; /* Add gap between items */
}

.logo {
    margin: 0;
    line-height: 1;
    display: inline-block;
}
.logo svg {
    display: block;
    height: 40px; /* Control height */
    width: auto;
    max-width: 100%;
}
.logo a {
    display: inline-block;
    line-height: 1;
}

/* Header Controls (Search + Theme Toggle) */
.header-controls {
    display: flex;
    align-items: center;
    gap: 0.75rem; /* Space between search and toggle */
    margin-left: auto; /* Push controls to the right on larger screens */
}

/* Search Input Styles */
.search-input {
    padding: 0.4rem 0.8rem;
    border-radius: 0.75rem; /* Squircle */
    border: 1px solid rgba(255, 255, 255, 0.2);
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--header-text);
    font-size: 0.875rem;
    transition: all 0.2s ease;
    max-width: 150px; /* Limit width initially */
}
.search-input::placeholder {
    color: rgba(255, 255, 255, 0.6);
}
.search-input:focus {
    outline: none;
    border-color: rgba(255, 255, 255, 0.5);
    background-color: rgba(255, 255, 255, 0.2);
    box-shadow: 0 0 0 2px rgba(165, 180, 252, 0.4); /* Use a light focus ring */
    max-width: 200px; /* Expand on focus */
}
body.dark-mode .search-input {
    border-color: rgba(75, 85, 99, 0.6);
    background-color: rgba(55, 65, 81, 0.3);
    color: var(--nav-link-text);
}
body.dark-mode .search-input::placeholder {
    color: rgba(156, 163, 175, 0.6); /* gray-400 */
}
body.dark-mode .search-input:focus {
    border-color: rgba(107, 114, 128, 0.8);
    background-color: rgba(75, 85, 99, 0.5);
    box-shadow: 0 0 0 2px rgba(156, 163, 175, 0.4);
}


/* Theme Toggle Button Styles */
.theme-toggle-button {
    background-color: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: var(--header-text);
    padding: 0.5rem; /* Square padding */
    border-radius: 50%; /* Make it round */
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 1rem; /* Adjust icon size */
    line-height: 1; /* Ensure icon is centered */
    display: flex;
    align-items: center;
    justify-content: center;
}
.theme-toggle-button:hover {
    background-color: rgba(255, 255, 255, 0.2);
    transform: scale(1.1);
}
body.dark-mode .theme-toggle-button {
    background-color: rgba(55, 65, 81, 0.3);
    border-color: rgba(75, 85, 99, 0.6);
    color: var(--nav-link-text);
}
body.dark-mode .theme-toggle-button:hover {
    background-color: rgba(75, 85, 99, 0.5);
}


.main-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.5rem 0.75rem;
    width: 100%; /* Take full width on mobile */
    margin-top: 0.5rem; /* Space below logo/controls on mobile */
}

.nav-link {
    color: var(--nav-link-text);
    padding: 0.5rem 0.75rem;
    border-radius: 0.75rem;
    transition: background-color 0.2s ease, color 0.2s ease;
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
    display: inline-block;
}
.nav-link:hover {
    color: var(--header-text);
    background-color: var(--nav-link-hover-bg);
}
.nav-link.active {
     color: var(--header-text);
     background-color: var(--nav-link-active-bg);
     font-weight: 600;
}


/* === Main Content === */
.main-content {
    margin-top: 1.5rem;
    padding-bottom: 2rem;
}

.content-section {
    background-color: var(--content-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--content-border);
    border-radius: 1.5rem;
    padding: 1.5rem 2rem;
    box-shadow: 0 8px 32px 0 var(--content-shadow);
    margin-bottom: 2.5rem;
    scroll-margin-top: 6rem;
    color: var(--content-text);
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}
/* Add bottom padding specifically to intro section */
#intro.content-section {
    padding-bottom: 4rem; /* pb-16 */
}

/* Section Headers */
.section-header {
    font-size: 2.25rem;
    font-weight: 700;
    border-bottom: 2px solid var(--section-border);
    padding-bottom: 0.75rem;
    margin-bottom: 2rem;
    color: var(--heading-text);
    transition: color 0.3s ease, border-color 0.3s ease;
}

h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--subheading-text);
    margin-top: 2rem;
    margin-bottom: 1rem;
    border-bottom: 1px solid rgba(209, 213, 219, 0.5); /* Adjust alpha if needed */
    padding-bottom: 0.5rem;
    transition: color 0.3s ease, border-color 0.3s ease;
}
h3:first-of-type { margin-top: 0; }

h4 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--subheading-text);
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
    transition: color 0.3s ease;
}

/* Paragraphs and Lists */
p, ul, ol, dl { margin-bottom: 1rem; }
li { margin-bottom: 0.5rem; }
ul, ol { padding-left: 1.5rem; }
ul { list-style: disc; }
ol { list-style: decimal; }

/* === Code Block Styling === */
.code-block-wrapper {
    position: relative;
    margin-bottom: 1.5rem;
}

code { /* Inline code */
    background-color: var(--code-inline-bg);
    padding: 0.2rem 0.45rem;
    border-radius: 0.375rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9em;
    color: var(--code-inline-text);
    word-wrap: break-word;
    border: 1px solid var(--code-inline-border);
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

pre { /* Code block container */
    background-color: var(--code-block-bg);
    border: 1px solid var(--code-block-border);
    padding: 1.25rem;
    padding-right: 4.5rem;
    border-radius: 1rem;
    overflow-x: auto;
    white-space: pre;
    margin-top: 0.5rem;
    font-size: 0.9em;
    box-shadow: inset 0 2px 4px 0 rgba(0, 0, 0, 0.04);
    font-family: 'JetBrains Mono', monospace;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

pre code { /* Code inside pre */
    background-color: transparent;
    padding: 0;
    border-radius: 0;
    color: var(--code-block-text);
    font-family: inherit;
    word-wrap: normal;
    white-space: pre;
    border: none;
    font-size: 1em;
    line-height: 1.5;
    transition: color 0.3s ease;
}

/* Copy Button */
.copy-button {
    position: absolute;
    top: 1rem;
    right: 1rem;
    padding: 0.3rem 0.6rem;
    font-size: 0.75rem;
    background-color: rgba(129, 140, 248, 0.7);
    color: #1e1b4b;
    border: 1px solid rgba(165, 180, 252, 0.5);
    border-radius: 0.5rem;
    cursor: pointer;
    opacity: 0.8;
    transition: all 0.2s ease;
    font-weight: 500;
}
.copy-button:hover {
    opacity: 1;
    background-color: rgba(165, 180, 252, 0.8);
    transform: scale(1.05);
}
.copy-button.copied {
    background-color: rgba(52, 211, 153, 0.8);
    color: #064e3b;
    border-color: rgba(110, 231, 183, 0.5);
    cursor: default;
    transform: scale(1);
}
/* Dark mode adjustments for copy button if needed */
body.dark-mode .copy-button {
     background-color: rgba(99, 102, 241, 0.6); /* indigo-500 */
     color: #e0e7ff; /* indigo-100 */
     border-color: rgba(129, 140, 248, 0.5); /* indigo-400 */
}
body.dark-mode .copy-button:hover {
    background-color: rgba(129, 140, 248, 0.7); /* indigo-400 */
}
body.dark-mode .copy-button.copied {
    background-color: rgba(16, 185, 129, 0.7); /* emerald-500 */
    color: #d1fae5; /* emerald-100 */
    border-color: rgba(52, 211, 153, 0.5); /* emerald-400 */
}


/* Syntax Highlighting Colors */
.html-tag { color: var(--syntax-html-tag); font-weight: 500; }
.html-attr { color: var(--syntax-html-attr); }
.html-value { color: var(--syntax-html-value); }
.html-comment { color: var(--syntax-comment); font-style: italic; opacity: 0.7; }

.css-selector { color: var(--syntax-css-selector); font-weight: 500; }
.css-property { color: var(--syntax-css-property); }
.css-value { color: var(--syntax-css-value); }
.css-comment { color: var(--syntax-comment); font-style: italic; opacity: 0.7; }
.css-unit { color: var(--syntax-html-tag); } /* Reusing blue */
.css-important { color: #dc2626; font-weight: bold; }

.js-keyword { color: var(--syntax-js-keyword); font-weight: 500; }
.js-variable { color: var(--code-block-text); } /* Use base code color */
.js-string { color: var(--syntax-js-string); }
.js-number { color: var(--syntax-js-number); }
.js-function { color: var(--syntax-js-function); }
.js-parameter { color: #7e22ce; } /* Keep specific purple */
.js-object-prop { color: #9333ea; } /* Keep specific purple */
.js-method { color: var(--syntax-js-function); }
.js-comment { color: var(--syntax-comment); font-style: italic; opacity: 0.7; }
.js-operator { color: var(--syntax-js-operator); opacity: 0.8; }
.js-boolean { color: var(--syntax-js-number); font-weight: 500; } /* Reusing pink */


/* Links within content */
.text-link {
    color: var(--link-text);
    text-decoration: underline;
    font-weight: 500;
    transition: color 0.2s ease;
}
.text-link:hover {
    color: var(--link-hover-text);
}

/* Call-to-action Button (General) */
.cta-button {
    display: inline-block;
    background-image: linear-gradient(to right, var(--button-cta-gradient-start), var(--button-cta-gradient-end));
    color: white;
    padding: 0.8rem 1.8rem;
    border-radius: 1rem;
    text-decoration: none;
    font-weight: 500;
    font-size: 1rem;
    border: none;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px var(--button-cta-shadow);
    text-align: center;
}
.cta-button:hover {
    background-image: linear-gradient(to right, var(--button-cta-hover-start), var(--button-cta-hover-end));
    box-shadow: 0 7px 20px rgba(124, 58, 237, 0.4); /* Keep shadow color consistent for now */
    transform: translateY(-2px);
}
.cta-button:active {
    transform: translateY(0px) scale(0.98);
    box-shadow: 0 2px 8px rgba(124, 58, 237, 0.2);
}

/* Specific margin for the main CTA button container on index.html */
.cta-button-container {
    margin-top: 5rem;
    text-align: center;
}


/* Quiz Specific Styles */
.quiz-container {
    margin-top: 2.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--quiz-border);
    transition: border-color 0.3s ease;
}
.quiz-container h3 {
    color: var(--quiz-legend-text); /* Use a variable */
    border-bottom: none;
    margin-bottom: 1.5rem;
    transition: color 0.3s ease;
}
.quiz-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}
.quiz-question {
    padding: 1rem;
    border: 1px solid var(--quiz-border);
    border-radius: 0.75rem;
    background-color: var(--quiz-bg);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}
.quiz-question legend {
    font-size: 1.125rem;
    font-weight: 500;
    margin-bottom: 0.75rem;
    padding: 0 0.25rem;
    color: var(--quiz-legend-text);
    transition: border-bottom 0.3s ease, color 0.3s ease;
}
.quiz-question div { margin-bottom: 0.5rem; }
.quiz-question label {
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: border-bottom 0.3s ease;
}
.quiz-question input[type="radio"] {
    cursor: pointer;
    accent-color: var(--link-text); /* Use theme color */
}

/* Quiz Submit Button Styling */
.quiz-submit-button {
    /* Inherit from .cta-button but override background */
    background-image: linear-gradient(to right, #a78bfa, #8b5cf6); /* Lighter violet gradient */
    padding: 0.6rem 1.2rem;
    font-size: 0.95rem;
    margin-top: 1rem;
    align-self: flex-start;
    box-shadow: 0 3px 10px rgba(139, 92, 246, 0.3);
}
.quiz-submit-button:hover {
    background-image: linear-gradient(to right, #8b5cf6, #7c3aed);
    box-shadow: 0 5px 15px rgba(139, 92, 246, 0.4);
    transform: translateY(-1px);
}
.quiz-submit-button:active {
    background-image: linear-gradient(to right, #7c3aed, #6d28d9);
    transform: translateY(0px) scale(0.97);
    box-shadow: 0 1px 5px rgba(139, 92, 246, 0.2);
}
/* Dark mode adjustments for quiz submit */
body.dark-mode .quiz-submit-button {
    background-image: linear-gradient(to right, #c4b5fd, #a78bfa);
    color: #3730a3; /* indigo-800 */
    box-shadow: 0 3px 10px rgba(196, 181, 253, 0.2);
}
body.dark-mode .quiz-submit-button:hover {
    background-image: linear-gradient(to right, #a78bfa, #8b5cf6);
    box-shadow: 0 5px 15px rgba(196, 181, 253, 0.3);
}
body.dark-mode .quiz-submit-button:active {
    background-image: linear-gradient(to right, #8b5cf6, #7c3aed);
    box-shadow: 0 1px 5px rgba(196, 181, 253, 0.15);
}


.quiz-results {
    margin-top: 1.5rem;
    padding: 1rem;
    border-radius: 0.75rem;
    background-color: var(--quiz-results-bg);
    border: 1px solid var(--quiz-results-border);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}
.quiz-results p { margin-bottom: 0.5rem; }
.quiz-results p:last-child { margin-bottom: 0; }
.quiz-results strong { font-weight: 600; }
.quiz-results .final-score {
    font-size: 1.125rem;
    font-weight: 600;
    margin-top: 1rem;
    padding-top: 0.5rem;
    border-top: 1px solid var(--quiz-border); /* Use quiz border color */
    transition: border-color 0.3s ease;
}


/* Interactive Demo */
.interactive-demo {
    background-color: rgba(245, 243, 255, 0.5);
    border: 1px solid rgba(196, 181, 253, 0.5);
    padding: 1.5rem;
    border-radius: 1rem;
    margin-top: 1rem;
    margin-bottom: 1rem;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}
body.dark-mode .interactive-demo {
    background-color: rgba(55, 48, 163, 0.3); /* indigo-900 */
    border-color: rgba(99, 102, 241, 0.4); /* indigo-500 */
}
.interactive-demo label {
    color: #5b21b6;
    display: block;
    margin-bottom: 0.25rem;
    font-weight: 500;
    transition: color 0.3s ease;
}
body.dark-mode .interactive-demo label { color: #a5b4fc; }

.interactive-demo input[type="text"] {
    background-color: rgba(255, 255, 255, 0.7);
    border: 1px solid rgba(196, 181, 253, 0.7);
    border-radius: 0.5rem;
    padding: 0.5rem 0.75rem;
    width: 100%;
    max-width: 300px;
    margin-bottom: 0.75rem;
    box-shadow: inset 0 1px 2px rgba(0,0,0,0.05);
    color: #3730a3;
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}
body.dark-mode .interactive-demo input[type="text"] {
    background-color: rgba(55, 65, 81, 0.4); /* gray-700 */
    border-color: rgba(75, 85, 99, 0.7); /* gray-600 */
    color: #e5e7eb; /* gray-200 */
}
.interactive-demo input[type="text"]:focus {
     border-color: #a78bfa;
     box-shadow: 0 0 0 2px rgba(124, 58, 237, 0.3);
     outline: none;
}
body.dark-mode .interactive-demo input[type="text"]:focus {
    border-color: #c4b5fd; /* violet-300 */
    box-shadow: 0 0 0 2px rgba(167, 139, 250, 0.3); /* violet-400 */
}

.interactive-demo button {
    background-color: #4f46e5;
    color: white;
    padding: 0.6rem 1.2rem;
    border-radius: 0.75rem;
    border: none;
    cursor: pointer;
    transition: background-color 0.2s ease, transform 0.1s ease;
    font-weight: 500;
    box-shadow: 0 2px 8px rgba(79, 70, 229, 0.3);
}
.interactive-demo button:hover { background-color: #4338ca; }
.interactive-demo button:active { transform: scale(0.98); }
.interactive-demo button:disabled {
    background-color: #a7a29b;
    cursor: not-allowed;
    box-shadow: none;
}
body.dark-mode .interactive-demo button {
    background-color: #6366f1; /* indigo-500 */
    box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
}
body.dark-mode .interactive-demo button:hover { background-color: #4f46e5; }
body.dark-mode .interactive-demo button:disabled { background-color: #6b7280; }


.output-area {
    margin-top: 1rem;
    padding: 0.75rem 1rem;
    background-color: rgba(255, 255, 255, 0.6);
    border: 1px dashed var(--quiz-border); /* Use quiz border color */
    min-height: 2.5rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9em;
    color: #581c87;
    border-radius: 0.5rem;
    word-wrap: break-word;
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}
body.dark-mode .output-area {
    background-color: rgba(55, 65, 81, 0.3); /* gray-700 */
    border-color: rgba(107, 114, 128, 0.5); /* gray-500 */
    color: #e0e7ff; /* indigo-100 */
}


/* Important Note Box */
.important-note {
    background-color: var(--important-note-bg);
    border: 1px solid var(--important-note-border);
    color: var(--important-note-text);
    padding: 0.75rem 1rem;
    border-radius: 0.75rem;
    font-size: 0.875rem;
    font-weight: 500;
    margin-top: 1.5rem;
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}
.important-note strong { color: var(--important-note-strong); }
.important-note a {
    color: var(--important-note-text);
    font-weight: 600;
    text-decoration: underline;
}
.important-note a:hover { color: var(--important-note-strong); }

/* Images */
img {
    max-width: 100%;
    height: auto;
    display: block;
    border-radius: 0.75rem;
}
.box-model-diagram {
     max-width: 450px;
     margin: 1rem auto;
     border: 1px solid rgba(255, 255, 255, 0.2);
     box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}
body.dark-mode .box-model-diagram {
    border-color: rgba(75, 85, 99, 0.4);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}


/* Footer */
.main-footer {
    background-color: var(--footer-bg);
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
    border-top: 1px solid var(--footer-border);
    color: var(--footer-text);
    padding: 1.5rem 0;
    margin-top: 3rem;
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}
.footer-container {
    text-align: center;
    font-size: 0.875rem;
}

/* === Responsive Adjustments === */
@media (min-width: 768px) { /* Medium screens and up */
    .header-container {
        flex-direction: row;
        align-items: center;
    }
    .logo {
        margin-bottom: 0;
    }
    /* Allow header controls and nav to sit side-by-side */
    .header-container > nav, .header-container > .header-controls {
        width: auto; /* Reset width */
        margin-top: 0; /* Reset margin */
    }
    .main-nav {
        justify-content: flex-start; /* Align nav links normally */
        margin-left: 1rem; /* Space between controls and nav */
    }
    .header-controls {
         margin-left: auto; /* Push controls to the right */
         order: 3; /* Ensure controls come after nav visually if needed */
    }
     .main-nav {
         order: 2; /* Ensure nav comes after logo */
     }
     .logo {
         order: 1;
     }

    .nav-link { font-size: 1rem; }
    .section-header { font-size: 2.25rem; }
    .content-section { padding: 2rem 2.5rem; }
}

@media (max-width: 767px) { /* Ensure controls stack nicely on mobile */
    .header-container {
        gap: 0.75rem; /* Add gap for stacked items */
    }
    .header-controls {
        width: 100%; /* Make controls take full width */
        justify-content: flex-end; /* Align controls to the right */
        margin-left: 0; /* Reset margin */
    }
    .main-nav {
         justify-content: center; /* Center nav links */
         width: 100%;
    }
}

/* === Search Results Highlighting === */
.search-highlight {
    background-color: #fef08a; /* yellow-200 */
    color: #713f12; /* yellow-900 */
    border-radius: 3px;
    padding: 0.1em 0.2em;
    font-weight: bold;
}
body.dark-mode .search-highlight {
    background-color: #facc15; /* yellow-400 */
    color: #422006; /* yellow-950 */
}

/* Hide sections not matching search */
.content-section.hidden-by-search {
    display: none;
}