@import url('https://fonts.googleapis.com/css2?family=Spline+Sans+Mono:wght@300;400;500;600;700&family=Lora:ital,wght@0,400..700;1,400..700&family=Inter:wght@300;400;600;700&display=swap');

:root {
    --bg-main: #f0f2f5;
    --sidebar-bg: #ffffff;
    --content-bg: #ffffff;
    --text-primary: #1a1a1b;
    --text-secondary: #4f5660;
    --accent-blue: #0056b3;
    --accent-green: #2d8a39;
    --accent-red: #c42b1c;
    --border-color: #d1d9e0;
    --code-bg: #f6f8fa;
    --font-serif: 'Lora', serif;
    --font-sans: 'Inter', sans-serif;
    --font-mono: 'Spline Sans Mono', monospace;
}

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

body {
    background-color: var(--bg-main);
    color: var(--text-primary);
    font-family: var(--font-sans);
    line-height: 1.6;
    display: flex;
    min-height: 100vh;
}

/* Sidebar Navigation */
.sidebar {
    width: 280px;
    background-color: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    padding: 20px;
    height: 100vh;
    position: sticky;
    top: 0;
    overflow-y: auto;
}

.sidebar h2 {
    font-size: 0.9rem;
    text-transform: uppercase;
    color: var(--text-secondary);
    margin-bottom: 15px;
    letter-spacing: 1px;
}

.sidebar-links {
    list-style: none;
}

.sidebar-links li {
    margin-bottom: 8px;
}

.sidebar-links a {
    text-decoration: none;
    color: var(--text-primary);
    font-size: 0.95rem;
    display: block;
    padding: 5px 10px;
    border-radius: 4px;
}

.sidebar-links a:hover {
    background: var(--bg-main);
    color: var(--accent-blue);
}

.sidebar-links a.active {
    background: #eef3ff;
    color: var(--accent-blue);
    font-weight: 600;
}

/* Main Content Area */
.main-content {
    flex: 1;
    padding: 40px 60px;
    max-width: 1000px;
    background-color: var(--content-bg);
}

header {
    border-bottom: 2px solid var(--border-color);
    margin-bottom: 40px;
    padding-bottom: 20px;
}

h1 {
    font-family: var(--font-serif);
    font-size: 2.5rem;
    margin-bottom: 10px;
}

.lesson-meta {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

section {
    margin-bottom: 60px;
}

h2 {
    font-family: var(--font-serif);
    font-size: 1.8rem;
    margin: 40px 0 20px 0;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-color);
}

h3 {
    font-size: 1.3rem;
    margin: 30px 0 15px 0;
}

p {
    margin-bottom: 20px;
}

/* LearnCPP Style Boxes */
.box {
    padding: 20px;
    margin: 25px 0;
    border-radius: 8px;
    border-left: 5px solid;
}

.box-tutorial {
    background-color: #f0f7ff;
    border-color: var(--accent-blue);
}

.box-warning {
    background-color: #fff4f4;
    border-color: var(--accent-red);
}

.box-key {
    background-color: #f4fff4;
    border-color: var(--accent-green);
}

.box-header {
    font-weight: 700;
    margin-bottom: 10px;
    text-transform: uppercase;
    font-size: 0.85rem;
}

code {
    font-family: var(--font-mono);
    background: #f1f3f5;
    padding: 2px 4px;
    border-radius: 3px;
    font-size: 0.9em;
}

pre {
    background-color: var(--code-bg);
    border: 1px solid var(--border-color);
    padding: 20px;
    border-radius: 6px;
    font-family: var(--font-mono);
    font-size: 0.9rem;
    overflow-x: auto;
    margin: 20px 0;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin: 25px 0;
}

th,
td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

th {
    background-color: #f8f9fa;
    font-weight: 600;
}

.nav-buttons {
    display: flex;
    justify-content: space-between;
    margin-top: 60px;
    padding-top: 30px;
    border-top: 2px solid var(--border-color);
}

.btn {
    text-decoration: none;
    color: #fff;
    background: var(--accent-blue);
    padding: 10px 20px;
    border-radius: 4px;
    font-weight: 600;
}

.btn:hover {
    filter: brightness(1.2);
}



@media (max-width: 800px) {
    body {
        flex-direction: column;
    }

    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
    }

    .main-content {
        padding: 30px 20px;
    }
}