/* style.css */

/* --- DESIGN SYSTEM: 1960s ENGINEERING REPORT --- */
:root {
    --bg-color: #fdfbf7; /* Old paper off-white */
    --text-color: #2a2a2a; /* Dark ink */
    --accent-color: #003366; /* Blueprint Blue */
    --highlight-color: #b83b3b; /* "Top Secret" Red */
    --font-body: 'Georgia', serif;
    --font-tech: 'Courier New', monospace;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    padding: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-body);
    display: flex;
    min-height: 100vh;
}

/* --- SIDEBAR NAVIGATION --- */
aside {
    width: 280px;
    background-color: #e8e4da;
    padding: 2rem;
    border-right: 2px solid var(--text-color);
    position: fixed;
    height: 100vh;
    overflow-y: auto;
}

aside h2 {
    font-family: var(--font-tech);
    font-size: 1.2rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    border-bottom: 2px solid var(--text-color);
    padding-bottom: 0.5rem;
    margin-bottom: 1.5rem;
}

nav ul {
    list-style: none;
    padding: 0;
}

nav li {
    margin-bottom: 1rem;
}

nav a {
    text-decoration: none;
    color: var(--text-color);
    font-family: var(--font-tech);
    font-size: 0.9rem;
    transition: color 0.2s;
}

nav a:hover {
    color: var(--accent-color);
    font-weight: bold;
}

/* This class highlights the page you are currently on */
nav a.current {
    color: var(--highlight-color);
    font-weight: bold;
    border-left: 3px solid var(--highlight-color);
    padding-left: 10px;
}

/* --- MAIN CONTENT AREA --- */
main {
    margin-left: 280px; /* Matches sidebar width */
    padding: 4rem 10%;
    max-width: 1200px;
}

header.book-title {
    margin-bottom: 4rem;
    text-align: center;
    border-bottom: 4px double var(--text-color);
    padding-bottom: 2rem;
}

h1 {
    font-size: 3rem;
    margin: 0;
    text-transform: uppercase;
    letter-spacing: 5px;
}

.subtitle {
    font-family: var(--font-tech);
    color: var(--accent-color);
    margin-top: 1rem;
    display: block;
}

/* --- CHAPTER STYLING --- */
article.chapter {
    margin-bottom: 6rem;
    padding-top: 2rem;
}

h3.chapter-number {
    font-family: var(--font-tech);
    color: var(--accent-color);
    font-size: 1rem;
    text-transform: uppercase;
}

h2.chapter-title {
    font-size: 2.2rem;
    margin-top: 0.5rem;
    margin-bottom: 2rem;
}

p {
    font-size: 1.1rem;
    line-height: 1.7;
    margin-bottom: 1.5rem;
}

/* --- TECHNICAL CALLOUT BOX (BLUEPRINT STYLE) --- */
.tech-spec {
    background-color: var(--accent-color);
    color: white;
    padding: 1.5rem;
    font-family: var(--font-tech);
    margin: 2rem 0;
    border: 1px solid var(--text-color);
    box-shadow: 5px 5px 0px rgba(0,0,0,0.2);
}

.tech-spec h4 {
    margin-top: 0;
    border-bottom: 1px dashed