:root {
    --primary-color: #00d2ff;
    --primary-gradient: linear-gradient(135deg, #00d2ff 0%, #3a7bd5 100%);
    --secondary-color: rgba(255, 255, 255, 0.05);
    --accent-color: #f39c12;
    --text-color: #e0e6ed;
    /* Light gray for readability on dark */
    --light-text: #a0aec0;
    --border-color: rgba(255, 255, 255, 0.1);
    --glass-bg: rgba(11, 14, 20, 0.5);
    /* Dark glassy bg */
    --glass-border: rgba(255, 255, 255, 0.1);
    --sidebar-bg: var(--glass-bg);
    --card-bg: rgba(11, 14, 20, 0.7);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 20px 50px rgba(0, 0, 0, 0.5);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
}

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

body {
    font-family: 'Inter', sans-serif;
    color: var(--text-color);
    background-color: #0b0e14;
    /* Deep space color fallback */
    line-height: 1.6;
    position: relative;
    min-height: 100vh;
}

#spaceBackground {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    pointer-events: none;
    /* Let clicks pass through to content */
}

header {
    background: rgba(11, 14, 20, 0.6);
    /* Glassy dark background */
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-container {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
}

.tech-text {
    color: #ffffff;
    text-shadow: 0 0 10px rgba(255, 255, 255, 0.5);
    /* Glowing text */
}

.sub-text {
    color: #00d2ff;
    /* Neon bright cyan */
    text-shadow: 0 0 10px rgba(0, 210, 255, 0.5);
}

nav ul {
    display: flex;
    list-style: none;
    gap: 2rem;
}

nav ul li a {
    text-decoration: none;
    color: rgba(255, 255, 255, 0.7);
    font-weight: 500;
    transition: var(--transition);
}

nav ul li a:hover,
nav ul li a.active {
    color: #00d2ff;
    text-shadow: 0 0 8px rgba(0, 210, 255, 0.6);
}

.search-box {
    position: relative;
    width: 300px;
}

.search-box input {
    padding: 0.8rem 1.2rem;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 30px;
    /* Pill shape for modern look */
    width: 100%;
    font-size: 0.95rem;
    font-family: inherit;
    transition: var(--transition);
    background: rgba(255, 255, 255, 0.05);
    /* Very subtle white */
    color: #ffffff;
    /* White text for input */
}

.search-box input::placeholder {
    color: rgba(255, 255, 255, 0.4);
}

.search-box input:focus {
    outline: none;
    border-color: #00d2ff;
    box-shadow: 0 0 15px rgba(0, 210, 255, 0.3);
    background: rgba(255, 255, 255, 0.1);
}

main {
    display: grid;
    grid-template-columns: 280px 1fr;
    max-width: 1400px;
    margin: 2rem auto;
    gap: 2rem;
    padding: 0 2rem;
}

.sidebar {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    padding: 1.5rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-md);
    height: fit-content;
    position: sticky;
    top: 100px;
}

.filter-section {
    margin-bottom: 2rem;
}

.filter-section h3 {
    font-size: 0.85rem;
    color: var(--light-text);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    font-weight: 700;
}

.filter-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.2rem;
}

.clear-btn {
    background: none;
    border: none;
    color: var(--primary-color);
    font-size: 0.75rem;
    font-weight: 600;
    cursor: pointer;
    padding: 4px 8px;
    border-radius: 4px;
    transition: var(--transition);
}

.clear-btn:hover {
    background: var(--secondary-color);
    text-decoration: underline;
}

.filter-group {
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
}

/* Custom Checkbox Styles */
.checkbox-container {
    display: block;
    position: relative;
    padding-left: 35px;
    margin-bottom: 12px;
    cursor: pointer;
    font-size: 0.95rem;
    user-select: none;
    transition: var(--transition);
}

.checkbox-container:hover {
    color: var(--primary-color);
}

.subjects-hierarchy {
    gap: 0.5rem;
}

.category-group {
    margin-bottom: 0.5rem;
}

.category-label {
    font-weight: 600;
    display: flex !important;
    align-items: center;
    justify-content: space-between;
}

.toggle-icon {
    font-size: 0.7rem;
    color: var(--light-text);
    transition: var(--transition);
    margin-left: auto;
    cursor: pointer;
    padding: 5px;
}

.category-group.collapsed .toggle-icon {
    transform: rotate(-90deg);
}

.sub-categories {
    padding-left: 20px;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    max-height: 500px;
    overflow: hidden;
    transition: max-height 0.3s ease-out, opacity 0.3s ease-out;
    margin-top: 0.5rem;
}

.category-group.collapsed .sub-categories {
    max-height: 0;
    opacity: 0;
    margin-top: 0;
}

.sub-filter {
    font-size: 0.85rem !important;
}

.checkbox-container input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    position: absolute;
    top: 0;
    left: 0;
    height: 20px;
    width: 20px;
    background-color: #eee;
    border-radius: 4px;
    transition: var(--transition);
}

.checkbox-container:hover input~.checkmark {
    background-color: #ccc;
}

.checkbox-container input:checked~.checkmark {
    background-color: var(--primary-color);
}

.checkmark:after {
    content: "";
    position: absolute;
    display: none;
}

.checkbox-container input:checked~.checkmark:after {
    display: block;
}

.checkbox-container .checkmark:after {
    left: 7px;
    top: 3px;
    width: 5px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

/* Content Area */
.content {
    min-width: 0;
}

.content-header {
    margin-bottom: 2rem;
}

.content-header h1 {
    font-size: 2rem;
    font-weight: 700;
}

.sim-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 2rem;
}

/* Card Styling */
.sim-card {
    background: var(--card-bg);
    border-radius: var(--radius-md);
    overflow: hidden;
    border: 1px solid var(--border-color);
    transition: var(--transition);
    cursor: pointer;
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-sm);
}

.sim-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.sim-card-image {
    width: 100%;
    aspect-ratio: 16/9;
    background: #eee;
    overflow: hidden;
}

.sim-card-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.sim-card:hover .sim-card-image img {
    transform: scale(1.05);
}

.sim-card-info {
    padding: 1.2rem;
    flex-grow: 1;
}

.sim-card-info h4 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
}

.sim-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tag {
    font-size: 0.75rem;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    background: rgba(0, 210, 255, 0.1);
    color: #00d2ff;
    font-weight: 600;
    border: 1px solid rgba(0, 210, 255, 0.3);
    text-shadow: 0 0 5px rgba(0, 210, 255, 0.4);
}

footer {
    text-align: center;
    padding: 4rem 2rem;
    color: rgba(255, 255, 255, 0.5);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    margin-top: 4rem;
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(12px);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 1;
}

.modal-content {
    background: rgba(11, 14, 20, 0.95);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    margin: auto;
    width: 90%;
    max-width: 1000px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-lg);
    position: relative;
    transform: translateY(30px);
    transition: transform 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    max-height: 90vh;
    display: flex;
    flex-direction: column;
}

.modal.active .modal-content {
    transform: translateY(0);
}

.close-modal {
    position: absolute;
    right: 25px;
    top: 20px;
    color: #aaa;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
    z-index: 10;
    transition: var(--transition);
}

.close-modal:hover {
    color: var(--primary-color);
}

.modal-header {
    padding: 2rem 2rem 1rem;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h2 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.modal-body {
    padding: 1rem 2rem 2rem;
    overflow-y: auto;
}

.modal-tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 2rem;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.tab-btn {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.05);
    padding: 0.8rem 1.5rem;
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--text-color);
    opacity: 0.9;
    cursor: pointer;
    position: relative;
    transition: var(--transition);
    border-radius: var(--radius-sm);
}

.tab-btn:hover {
    background: rgba(0, 129, 207, 0.1);
    color: var(--primary-color);
    opacity: 1;
}

.tab-btn:after {
    content: '';
    position: absolute;
    bottom: -0.5rem;
    left: 20%;
    width: 0;
    height: 4px;
    background: var(--primary-color);
    transition: var(--transition);
    border-radius: 2px;
}

.tab-btn.active {
    color: var(--primary-color);
}

.tab-btn.active:after {
    width: 60%;
}

.tab-content {
    display: none;
    animation: fadeIn 0.4s ease;
}

.tab-content.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Modal Content Components */
.modal-main-image {
    width: 100%;
    border-radius: 12px;
    overflow: hidden;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
}

.modal-main-image img {
    width: 100%;
    display: block;
}

.content-section-header {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
    margin: 2rem 0 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid rgba(0, 129, 207, 0.2);
}

.description-text,
#modalExplanation {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-color);
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: rgba(0, 0, 0, 0.2);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.explanation-text {
    font-size: 1rem;
    line-height: 1.8;
    color: var(--text-color);
    padding: 2rem;
    border-top: 1px solid var(--border-color);
    margin-top: 2rem;
    position: relative;
}

.explanation-text::before {
    content: "Scientific Explanation";
    display: block;
    font-size: 0.75rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.formula-container {
    background: rgba(0, 0, 0, 0.2);
    padding: 3rem;
    border-radius: 12px;
    display: flex;
    justify-content: center;
    align-items: center;
    border: 1px solid var(--border-color);
}

.formula-box {
    font-family: 'Courier New', Courier, monospace;
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    background: rgba(0, 0, 0, 0.4);
    padding: 1.5rem 3rem;
    border-radius: 8px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
    border: 1px solid var(--border-color);
}

.formula-display {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    font-family: 'Inter', sans-serif;
    margin-bottom: 2rem;
}

.symbols-list {
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
    padding: 1.5rem;
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-md);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.symbols-header {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--light-text);
    margin-bottom: 0.5rem;
    font-weight: 700;
}

.symbol-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    font-size: 1.1rem;
}

.symbol-key {
    font-weight: 800;
    color: var(--primary-color);
    min-width: 30px;
    font-family: 'Courier New', Courier, monospace;
}

.symbol-name {
    color: var(--text-color);
}

.examples-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.example-item {
    background: rgba(0, 0, 0, 0.2);
    padding: 1.5rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--accent-color);
}

.example-item h5 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.example-item p {
    color: var(--light-text);
    line-height: 1.6;
}

.quiz-container {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.quiz-item {
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
}

.quiz-question {
    font-weight: 700;
    font-size: 1.1rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
    display: flex;
    gap: 0.5rem;
}

.quiz-answer {
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* Mock Interactive Area - "The Lab" */
.mock-interactive-area {
    background: #0f172a;
    /* Deep Space Blue */
    border-radius: var(--radius-lg);
    padding: 2.5rem;
    margin-bottom: 2rem;
    color: #f8fafc;
    font-family: 'Inter', sans-serif;
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    position: relative;
    overflow: hidden;
}

/* Data Dashboard Styling */
.data-dashboard {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
    padding: 1rem;
    background: rgba(15, 23, 42, 0.8);
    border-radius: var(--radius-md);
    border: 1px solid rgba(255, 255, 255, 0.05);
    flex-wrap: wrap;
    justify-content: space-between;
}

.readout-item {
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
    padding: 0 0.5rem;
}

.readout-label {
    font-size: 0.6rem;
    font-weight: 800;
    color: #94a3b8;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.readout-value {
    font-family: 'JetBrains Mono', 'Courier New', monospace;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--primary-color);
}

.readout-unit {
    font-size: 0.7rem;
    color: #475569;
    font-weight: 400;
}

/* SVG Wave Styles */
.svg-wave-container {
    width: 100%;
    height: 180px;
    background: #020617;
    border-radius: var(--radius-md);
    border: 1px solid rgba(255, 255, 255, 0.05);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
}

.svg-wave-container::before {
    content: "";
    position: absolute;
    width: 200%;
    height: 100%;
    background-image:
        linear-gradient(rgba(56, 189, 248, 0.05) 1px, transparent 1px),
        linear-gradient(90deg, rgba(56, 189, 248, 0.05) 1px, transparent 1px);
    background-size: 20px 20px;
    pointer-events: none;
}

.wave-path {
    fill: none;
    stroke-width: 2;
    stroke-linecap: round;
    transition: stroke 0.3s ease;
}

.wave-source-a {
    stroke: rgba(0, 210, 255, 0.4);
    stroke-dasharray: 4, 4;
}

.wave-source-b {
    stroke: rgba(244, 114, 182, 0.4);
    stroke-dasharray: 4, 4;
}

.wave-resultant {
    stroke: #ffffff;
    stroke-width: 4;
    filter: drop-shadow(0 0 8px rgba(0, 210, 255, 0.8));
}


.mock-sim-header {
    font-size: 0.75rem;
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    text-transform: uppercase;
    letter-spacing: 0.2em;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.mock-sim-header::before {
    content: "";
    display: inline-block;
    width: 8px;
    height: 8px;
    background: var(--primary-color);
    border-radius: 50%;
    box-shadow: 0 0 10px var(--primary-color);
    animation: blink 2s infinite;
}

@keyframes blink {

    0%,
    100% {
        opacity: 1;
    }

    50% {
        opacity: 0.4;
    }
}

.mock-controls {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
    background: rgba(255, 255, 255, 0.03);
    padding: 1.5rem;
    border-radius: var(--radius-md);
    border: 1px solid rgba(255, 255, 255, 0.05);
    z-index: 10;
    position: relative;
}

.mock-slider {
    width: 100%;
    height: 6px;
    background: #1e293b;
    border-radius: 3px;
    outline: none;
    accent-color: var(--primary-color);
    cursor: pointer;
    transition: opacity 0.2s;
}

.mock-slider:hover {
    opacity: 0.8;
}


.mock-viz {
    height: 350px;
    background: #020617;
    border-radius: var(--radius-md);
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.mock-viz::after {
    content: "";
    position: absolute;
    width: 100%;
    height: 100%;
    background-image:
        linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
    background-size: 40px 40px;
    pointer-events: none;
}


/* Specific Sim Elements - Premium Lab Edition */
.mock-object {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, #f59e0b, #d97706);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 800;
    box-shadow: 0 10px 20px -5px rgba(0, 0, 0, 0.4);
    z-index: 5;
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.mock-vector {
    position: absolute;
    left: 50%;
    height: 6px;
    background: #10b981;
    width: 0px;
    transform-origin: left;
    transition: width 0.1s linear;
    box-shadow: 0 0 15px rgba(16, 185, 129, 0.4);
}

.mock-vector::after {
    content: "";
    position: absolute;
    right: -12px;
    top: -6px;
    border-left: 14px solid #10b981;
    border-top: 9px solid transparent;
    border-bottom: 9px solid transparent;
}

.mock-wave {
    width: 100%;
    height: 80px;
    background: transparent;
    border-bottom: 4px solid var(--primary-color);
    filter: drop-shadow(0 0 15px rgba(0, 129, 207, 0.6));
    position: relative;
}

.energy-viz {
    display: flex;
    align-items: flex-end;
    gap: 2.5rem;
    height: 70%;
}

.energy-bar-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.8rem;
}

.energy-bar {
    width: 45px;
    background: var(--primary-color);
    border-radius: 6px 6px 0 0;
    transition: height 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    position: relative;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.5);
}

.pe-bar {
    background: linear-gradient(to top, #1d4ed8, #60a5fa);
    height: 50%;
}

.ke-bar {
    background: linear-gradient(to top, #b45309, #fbbf24);
    height: 50%;
}

.bar-label {
    font-size: 0.75rem;
    font-weight: 800;
    color: #64748b;
    text-transform: uppercase;
}

.gas-chamber {
    width: 85%;
    height: 85%;
    border: 3px solid #334155;
    border-radius: 8px;
    position: relative;
    background: rgba(15, 23, 42, 0.6);
    box-shadow: inset 0 0 30px rgba(0, 0, 0, 0.5);
}

.particle {
    width: 14px;
    height: 14px;
    background: radial-gradient(circle at 30% 30%, #38bdf8, #0369a1);
    border-radius: 50%;
    position: absolute;
    box-shadow: 0 0 12px rgba(56, 189, 248, 0.4);
}

.ruth-nucleus {
    width: 45px;
    height: 45px;
    background: radial-gradient(circle at 30% 30%, #f87171, #991b1b);
    border-radius: 50%;
    box-shadow: 0 0 40px rgba(239, 68, 68, 0.5);
    z-index: 10;
}

.alpha-point {
    width: 8px;
    height: 8px;
    background: #10b981;
    border-radius: 50%;
    position: absolute;
    box-shadow: 0 0 10px #10b981;
}

.bulb-lab {
    width: 100px;
    height: 100px;
    background: #1e293b;
    border-radius: 50%;
    border: 4px solid #334155;
    position: relative;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.atom-lab-viz {
    width: 300px;
    height: 300px;
    position: relative;
}

.nucleus-lab {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 60px;
    height: 60px;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-content: center;
    gap: 3px;
    z-index: 10;
}

.proton-lab {
    width: 16px;
    height: 16px;
    background: #ef4444;
    border-radius: 50%;
    box-shadow: 0 0 8px #ef4444;
}

.neutron-lab {
    width: 16px;
    height: 16px;
    background: #64748b;
    border-radius: 50%;
    box-shadow: 0 0 8px #64748b;
}

.electron-lab {
    width: 12px;
    height: 12px;
    background: #3b82f6;
    border-radius: 50%;
    position: absolute;
    box-shadow: 0 0 12px #3b82f6;
    offset-path: circle(100px);
    animation: e-orbit 3s linear infinite;
}

@keyframes e-orbit {
    from {
        offset-distance: 0%;
    }

    to {
        offset-distance: 100%;
    }
}

@keyframes moveElectron {
    from {
        offset-distance: 0%;
    }

    to {
        offset-distance: 100%;
    }
}

.graph-display {
    width: 90%;
    height: 90%;
    border-left: 3px solid #475569;
    border-bottom: 3px solid #475569;
    position: relative;
}

.graph-line-lab {
    position: absolute;
    width: 200%;
    height: 3px;
    background: var(--primary-color);
    box-shadow: 0 0 15px rgba(0, 129, 207, 0.5);
    transform-origin: left center;
}

.solar-lab {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.orbit-ellipse {
    position: absolute;
    border: 1px dashed rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    width: 280px;
    height: 160px;
}

.planet-lab {
    width: 18px;
    height: 18px;
    background: radial-gradient(circle at 30% 30%, #60a5fa, #1d4ed8);
    border-radius: 50%;
    position: absolute;
    offset-path: ellipse(140px 80px at 50% 50%);
    box-shadow: 0 0 15px rgba(59, 130, 246, 0.5);
}

.cannon-lab {
    width: 50px;
    height: 25px;
    background: #475569;
    border-radius: 4px;
    position: absolute;
    left: 20px;
    bottom: 20px;
    transform-origin: left bottom;
    border: 2px solid #64748b;
}

.projectile-lab {
    width: 12px;
    height: 12px;
    background: #ef4444;
    border-radius: 50%;
    position: absolute;
    opacity: 0;
    box-shadow: 0 0 10px rgba(239, 68, 68, 0.6);
}

@media (max-width: 992px) {
    main {
        grid-template-columns: 1fr;
    }

    .sidebar {
        position: static;
    }

    .header-container {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }

    nav ul {
        flex-wrap: wrap;
        justify-content: center;
        gap: 1rem;
    }

    .search-box input {
        width: 100%;
    }

    .modal-content {
        width: 100%;
        max-width: 100%;
        height: 100vh;
        max-height: 100vh;
        border-radius: 0;
    }
}

@keyframes pulse {
    0% {
        transform: scale(1);
        filter: drop-shadow(0 0 5px rgba(255, 255, 255, 0.2));
    }

    50% {
        transform: scale(1.1);
        filter: drop-shadow(0 0 20px rgba(59, 130, 246, 0.5));
    }

    100% {
        transform: scale(1);
        filter: drop-shadow(0 0 5px rgba(255, 255, 255, 0.2));
    }
}

/* ==========================================
   Footer Links & Info Pages Design System
   ========================================== */

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.2rem;
}

.footer-links {
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
}

.footer-links a {
    color: var(--light-text);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--primary-color);
    text-shadow: 0 0 8px rgba(0, 210, 255, 0.4);
}

.footer-links .separator {
    color: rgba(255, 255, 255, 0.15);
    user-select: none;
}

.info-page-container {
    max-width: 850px;
    margin: 3rem auto;
    padding: 3rem;
    background: var(--card-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-radius: var(--radius-lg);
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-lg);
    z-index: 10;
    position: relative;
}

.info-page-container h1 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 0 30px rgba(0, 210, 255, 0.15);
}

.info-page-container h2 {
    font-size: 1.4rem;
    font-weight: 700;
    margin: 2rem 0 1rem;
    color: var(--primary-color);
    border-bottom: 1px solid rgba(0, 210, 255, 0.15);
    padding-bottom: 0.5rem;
}

.info-page-container p, .info-page-container ul {
    margin-bottom: 1.5rem;
    color: var(--text-color);
    line-height: 1.8;
}

.info-page-container ul {
    padding-left: 1.5rem;
    list-style-type: square;
}

.info-page-container li {
    margin-bottom: 0.6rem;
}

.info-page-container strong {
    color: #ffffff;
}

.back-home-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 2rem;
    transition: var(--transition);
}

.back-home-btn:hover {
    transform: translateX(-5px);
    text-shadow: 0 0 8px rgba(0, 210, 255, 0.4);
}

/* Contact Form Styling */
.contact-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    margin-top: 2rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--light-text);
}

.form-group input, .form-group textarea {
    padding: 1rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-sm);
    background: rgba(11, 14, 20, 0.8);
    color: white;
    font-family: inherit;
    font-size: 0.95rem;
    transition: var(--transition);
}

.form-group input:focus, .form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    background: rgba(11, 14, 20, 0.95);
    box-shadow: 0 0 15px rgba(0, 210, 255, 0.25);
}

.btn-submit {
    padding: 1rem 2rem;
    background: var(--primary-gradient);
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    font-weight: 700;
    font-size: 1rem;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: 0 4px 15px rgba(0, 210, 255, 0.3);
}

.btn-submit:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 210, 255, 0.5);
}

.btn-submit:active {
    transform: translateY(0);
}

.form-success-msg {
    background: rgba(16, 185, 129, 0.1);
    border: 1px solid rgba(16, 185, 129, 0.3);
    color: #10b981;
    padding: 1.2rem;
    border-radius: var(--radius-sm);
    text-align: center;
    margin-top: 1.5rem;
    display: none;
    font-weight: 600;
    animation: fadeIn 0.4s ease;
}

.form-error-msg {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.3);
    color: #ef4444;
    padding: 1.2rem;
    border-radius: var(--radius-sm);
    text-align: center;
    margin-top: 1.5rem;
    display: none;
    font-weight: 600;
    animation: fadeIn 0.4s ease;
}

.btn-submit:disabled {
    background: rgba(255, 255, 255, 0.1) !important;
    color: var(--light-text) !important;
    cursor: not-allowed;
    box-shadow: none !important;
    transform: none !important;
}