:root {
    --page-background-color: #0d0d0d;
    --panel-surface-color: #1a1a1a;
    --panel-corner-radius: 0.25rem;
    --button-color-light: #2e2e2e;
    --button-color-dark: #060606;
    --divider-border-color-light: #2e2e2e;
    --divider-border-color-dark: #060606;
    --primary-text-color: #e0e0e0;
    --accent-color-base: #66B2FF;
    --accent-color-dark: #339CFF;
    --accent-color-light: #99CCFF;
    --base-font: 'Calibri', sans-serif;
    --base-font-size: 1rem;
    --large-heading-size: 1.5rem;
    --small-text-size: 0.85rem;
    --table-of-contents-width: 12rem;
    --navigation-panel-height: 4rem;
    --panel-gap-spacing: 1rem;
    --input-bg: #121212;
    --input-border-radius: 0.5rem;
    --input-border: 0.0625rem solid var(--accent-color-base);
    --toggle-width: 3rem;
    --toggle-height: 1.5rem;
    --toggle-slider-height: 1.75rem;
    --toggle-slider-radius: 1.5rem;
    --toggle-knob-size: 1.25rem;
    --toggle-knob-offset: 0.125rem;
    --checkbox-size: 1.25rem;
    --checkbox-radius: 0.25rem;
    --nav-btn-padding: 0.625rem 0.9375rem;
    --nav-btn-border: 0.125rem solid #444;
    --nav-btn-radius: 0.375rem;
    --nav-btn-bg: #222;
    --nav-btn-indicator-width: 2rem;
    --nav-btn-indicator-height: 0.375rem;
    --nav-btn-indicator-radius: 0.5rem;
    --focus-shadow: 0 0 0.5rem var(--accent-color-dark);
    --active-shadow: 0 0 0.25rem var(--accent-color-dark);
}

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

body {
    background-color: var(--page-background-color);
    font-family: var(--base-font);
    font-size: var(--base-font-size);
    color: var(--primary-text-color);
    line-height: 1.6;
}

/* Navigation Panel */
.navigation-panel {
    background-color: var(--panel-surface-color);
    height: var(--navigation-panel-height);
    display: flex;
    align-items: center;
    justify-content: center;
    border-bottom: 1px solid var(--divider-border-color-dark);
    position: sticky;
    top: 0;
    z-index: 1000;
    margin-bottom: var(--panel-gap-spacing);
}

/* Layout */
.page-layout {
    display: flex;
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
    gap: 1rem;
}

/* Content Panel */
.content-panel {
    background-color: var(--panel-surface-color);
    flex: 1;
    padding: 2rem;
    border-bottom: 1px solid var(--divider-border-color-dark);
    border-left: 1px solid var(--divider-border-color-light);
    border-right: 1px solid var(--divider-border-color-dark);
    border-top: 1px solid var(--divider-border-color-light);
    border-radius: var(--panel-corner-radius);
}

/* Footer */
.footer-nav {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-top: 1rem;
    margin-bottom: 2rem;
}

/* Table of Contents */
.table-of-contents {
    background-color: var(--panel-surface-color);
    width: var(--table-of-contents-width);
    padding: 1rem;
    border-bottom: 1px solid var(--divider-border-color-dark);
    border-left: 1px solid var(--divider-border-color-light);
    border-right: 1px solid var(--divider-border-color-dark);
    border-top: 1px solid var(--divider-border-color-light);
    position: sticky;
    top: calc(var(--navigation-panel-height) + var(--panel-gap-spacing));
    height: fit-content;
    margin-bottom: var(--panel-gap-spacing);
    border-radius: var(--panel-corner-radius);
}

/* Text Styling */
h1 {
    font-size: var(--large-heading-size);
    color: var(--accent-color-light);
    margin-bottom: 1rem;
}

h2 {
    margin-top: 2rem;
    font-size: 1.25rem;
}

p {
    margin-bottom: 1rem;
}

a {
    color: var(--accent-color-base);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

ul.table-of-contents-list {
    list-style: none;
}

ul.table-of-contents-list li {
    margin-bottom: 0.5rem;
}

.button-primary,
.button-secondary {
    border: var(--input-border);
    padding: 0.5rem 0.5rem;
    font-size: 1rem;
    border-radius: var(--input-border-radius);
    transition: all 0.2s ease-in-out;
    font-family: var(--base-font);
    color: #fff;
}

.button-primary {
    background: var(--accent-color-dark);
}

.button-primary:hover {
    box-shadow: var(--focus-shadow);
}

.button-primary:active {
    background: var(--accent-color-base);
    box-shadow: var(--active-shadow);
}

.button-secondary {
    background: var(--button-color-light);
}

.button-secondary:hover {
    box-shadow: var(--focus-shadow);
}

.button-secondary:active {
    background: var(--accent-color-dark);
    box-shadow: var(--active-shadow);
}

.input-text {
    background-color: var(--input-bg);
    border: var(--input-border);
    padding: 0.5rem;
    font-size: 1rem;
    color: #fff;
    border-radius: var(--input-border-radius);
    transition: all 0.2s ease-in-out;
    font-family: var(--base-font);
}

.input-text:focus,
.input-text:hover {
    outline: none;
    box-shadow: var(--focus-shadow);
}

label.toggle-container {
    position: relative;
    display: inline-block;
    width: var(--toggle-width);
    height: var(--toggle-height);
}

label.toggle-container input[type="checkbox"] {
    opacity: 0;
    width: 0;
    height: 0;
}

span.slider-track {
    position: absolute;
    height: var(--toggle-slider-height);
    width: var(--toggle-width);
    background-color: var(--button-color-dark);
    border: 0.125rem solid var(--accent-color-base);
    border-radius: var(--toggle-slider-radius);
    cursor: pointer;
    transition: all 0.2s ease-in-out;
}

span.slider-track::before {
    content: "";
    position: absolute;
    height: var(--toggle-knob-size);
    width: var(--toggle-knob-size);
    left: var(--toggle-knob-offset);
    bottom: var(--toggle-knob-offset);
    background-color: var(--button-color-light);
    border-radius: 50%;
    transition: all 0.2s ease-in-out;
}

input[type="checkbox"]:checked + span.slider-track {
    background-color: var(--accent-color-dark);
}
input[type="checkbox"]:hover + span.slider-track {
    box-shadow: var(--focus-shadow);
}

input[type="checkbox"]:checked + span.slider-track::before {
    transform: translateX(1.25rem);
    background-color: #fff;
}

label.checkbox-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1rem;
}

input.checkbox {
    appearance: none;
    width: var(--checkbox-size);
    height: var(--checkbox-size);
    background-color: var(--input-bg);
    border: 0.125rem solid var(--accent-color-base);
    border-radius: var(--checkbox-radius);
    position: relative;
    cursor: pointer;
    vertical-align: middle;
    transition: all 0.2s ease-in-out;
}

input.checkbox:checked {
    background-color: var(--accent-color-dark);
}

input.checkbox:checked::after {
    content: '✓';
    color: white;
    position: absolute;
    font-size: 1rem;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

input.checkbox:hover {
    box-shadow: var(--focus-shadow);
}

.nav-button {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    padding: var(--nav-btn-padding);
    border: var(--nav-btn-border);
    border-radius: var(--nav-btn-radius);
    background-color: var(--nav-btn-bg);
    color: white;
    cursor: pointer;
    transition: all 0.2s ease-in-out;
}

.nav-button:focus,
.nav-button:hover {
    outline: none;
    border-color: var(--accent-color-dark);
    text-decoration: none;
}

.nav-button .indicator {
    width: var(--nav-btn-indicator-width);
    height: var(--nav-btn-indicator-height);
    margin-top: 0.375rem;
    border-radius: var(--nav-btn-indicator-radius);
    background-color: black;
    transition: background-color 0.3s, box-shadow 0.3s;
}

.nav-button.active .indicator,
.nav-button:hover .indicator {
    background-color: var(--accent-color-dark);
    box-shadow: var(--focus-shadow);
}

.footer-link-list {
    display: flex;
    list-style: none;
    padding: 0;
    gap: 1rem;
}

.footer-link-list li:not(:last-child)::after {
    content: "|";
    margin-left: 0.5rem;
}