/* GLOBAL RESET & BOX-MODEL */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

/* BASE STYLES */
:root {
    --bg-dark: #121212;            /* Very dark background for contrast */
    --accent-vibrant: #00bcd4;     /* Cyan/Aqua for main highlight */
    --accent-secondary: #ff4081;   /* Pink for the main section title */
    --text-light: #f5f5f5;
    --glass-bg: rgba(255, 255, 255, 0.1); /* Semi-transparent white */
    --border-glass: rgba(255, 255, 255, 0.2);
    --shadow-soft: 0 8px 32px 0 rgba(0, 0, 0, 0.37); /* Deep shadow */
}

body {
    font-family: 'Poppins', sans-serif; /* A popular modern font */
    background-color: var(--bg-dark);
    color: var(--text-light);
    line-height: 1.6;
    display: flex; 
    /* To fully appreciate glassmorphism, the main body needs an interesting background texture or gradient,
       but we will keep it simple dark for high contrast here. */
}

/* HEADER STYLES (Floating over the glass) */
h1 {
    font-size: 2rem;
    padding: 25px 20px;
    margin: 0;
    font-weight: 800;
    color: var(--accent-vibrant);
    background: linear-gradient(135deg, var(--bg-dark), #2c2c2c); /* Dark gradient for depth */
    text-align: center;
    text-shadow: 1px 1px 5px rgba(0, 0, 0, 0.5); 
    border-bottom: 2px solid var(--accent-vibrant);
}

/* NAVIGATION BAR - GLASSMOPHISM EFFECT */
.navbar {
    width: 320px; /* Slightly wider for a more impressive effect */
    min-height: 100vh;
    background: var(--glass-bg); 
    box-shadow: var(--shadow-soft);
    backdrop-filter: blur(10px); /* The key Glassmorphism feature */
    -webkit-backdrop-filter: blur(10px); 
    border-right: 1px solid var(--border-glass);
    overflow-y: auto;
    position: sticky;
    top: 0;
}

.ul1 {
    list-style: none;
    padding: 20px 0;
    margin: 0;
}

/* LIST ITEM STYLES */
/* HTML BASICS main section title */
ol > li {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--accent-secondary); /* Eye-catching pink */
    padding: 20px 25px 10px 25px;
    text-transform: uppercase;
    letter-spacing: 1px;
    list-style: none;
}

/* Sub-list items */
ul li {
    padding: 0; 
    list-style: none;
}

/* LINKS */
a {
    color: var(--text-light);
    text-decoration: none;
    display: block;
    padding: 12px 25px 12px 40px; /* Increased padding */
    font-size: 1.05rem;
    border-left: 5px solid transparent; 
    transition: background-color 0.3s ease, color 0.3s ease, border-left 0.3s ease; /* Smooth transitions */
}

a:hover, a:focus {
    color: var(--accent-vibrant);
    background-color: rgba(0, 188, 212, 0.15); /* Light aqua overlay */
    border-left: 5px solid var(--accent-vibrant); /* Strong highlight bar */
}

/* BUTTON STYLES (Previous Button) */
.btn-default {
    margin: 40px 20px;
    padding: 12px 20px;
    background: linear-gradient(90deg, var(--accent-vibrant) 0%, #0097a7 100%); /* Gradient background */
    border: none;
    border-radius: 8px;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(0, 188, 212, 0.4);
    transition: all 0.3s ease;
}

.btn-default:hover {
    transform: translateY(-2px); /* Slight lift on hover */
    box-shadow: 0 6px 20px rgba(0, 188, 212, 0.6);
}

.previous {
    color: var(--bg-dark) !important; /* Dark text for contrast on bright button */
    font-weight: 700;
    display: inline; 
    padding: 0;
}

/* Clean up extra break tags */
.ul1 br {
    display: none;
}