@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;600;700;900&display=swap');

/* =========================================
   1. RESET & VARIABLES
   ========================================= */
:root {
    /* Color Palette - Cyber/Gaming Aesthetic */
    --color-bg-main: #0f172a;
    --color-bg-secondary: #1e293b;
    --color-bg-card: #334155;
    
    --color-primary: #3b82f6;
    --color-primary-dark: #2563eb;
    --color-accent: #8b5cf6; /* Violet */
    --color-accent-glow: #ec4899; /* Pink */
    
    --color-text-main: #f8fafc;
    --color-text-muted: #94a3b8;
    --color-text-dark: #0f172a;
    
    --color-success: #10b981;
    --color-border: rgba(255, 255, 255, 0.1);

    /* Typography */
    --font-family-base: 'Inter', system-ui, -apple-system, sans-serif;
    --font-size-base: 1rem;
    --line-height-base: 1.6;
    --font-size-h1: clamp(2.5rem, 5vw + 1rem, 4.5rem);
    --font-size-h2: clamp(1.8rem, 3vw + 1rem, 2.5rem);
    --font-size-h3: clamp(1.25rem, 2vw + 0.5rem, 1.75rem);

    /* Spacing & Layout */
    --container-width: 1200px;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;
    --radius-sm: 0.375rem;
    --radius-md: 0.75rem;
    --radius-lg: 1.5rem;
    --radius-full: 9999px;

    /* Effects */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -1px rgba(0, 0, 0, 0.15);
    --shadow-glow: 0 0 20px rgba(59, 130, 246, 0.4);
    --transition-base: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
    height: 100%;
}

body {
    font-family: var(--font-family-base);
    background-color: var(--color-bg-main);
    color: var(--color-text-main);
    line-height: var(--line-height-base);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

ul, ol {
    list-style: none;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* =========================================
   2. LAYOUT UTILITIES
   ========================================= */
.container {
    width: 100%;
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--spacing-sm);
}

section {
    padding: var(--spacing-lg) 0;
    position: relative;
}

/* =========================================
   3. HEADER & NAVIGATION
   ========================================= */
.intro {
    background: radial-gradient(circle at top right, #1e1b4b, var(--color-bg-main));
    padding-top: var(--spacing-md);
    padding-bottom: var(--spacing-xl);
    border-bottom: 1px solid var(--color-border);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) 0;
    margin-bottom: var(--spacing-lg);
    position: relative;
    z-index: 10;
}

.logo {
    font-weight: 900;
    font-size: 1.5rem;
    color: var(--color-text-main);
    letter-spacing: -0.05em;
    display: flex;
    align-items: center;
}

/* Create a placeholder logo if empty in HTML */
.logo:empty::after {
    content: 'UP X';
    background: linear-gradient(to right, var(--color-primary), var(--color-accent));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

nav ul {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
    background: rgba(255, 255, 255, 0.03);
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-full);
    border: 1px solid var(--color-border);
    backdrop-filter: blur(10px);
}

nav ul li a {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--color-text-muted);
    position: relative;
}

nav ul li a:hover,
nav ul li a:focus {
    color: var(--color-text-main);
}

nav ul li a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--color-primary);
    transition: var(--transition-base);
    border-radius: 2px;
}

nav ul li a:hover::after {
    width: 100%;
}

.border, .bor {
    /* Styling decorative line from HTML if needed, mostly hiding or resetting */
    display: none; 
}

/* Burger Menu (Visual Representation) */
.burger {
    display: none;
    width: 30px;
    height: 20px;
    position: relative;
    cursor: pointer;
}

.burger::before,
.burger::after {
    content: '';
    position: absolute;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--color-text-main);
    transition: var(--transition-base);
}

.burger::before { top: 0; }
.burger::after { bottom: 0; box-shadow: 0 -9px 0 0 var(--color-text-main); }

/* =========================================
   4. HERO SECTION (.intro .body)
   ========================================= */
.intro .body {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    max-width: 800px;
    animation: fadeInUp 0.8s ease-out;
}

.intro h1 {
    font-size: var(--font-size-h1);
    line-height: 1.1;
    margin-bottom: var(--spacing-md);
    font-weight: 900;
}

.intro h1 span {
    background: linear-gradient(135deg, var(--color-primary), var(--color-accent), var(--color-accent-glow));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    display: inline-block;
    filter: drop-shadow(0 0 15px rgba(59, 130, 246, 0.3));
}

.intro p {
    font-size: 1.125rem;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-md);
    max-width: 600px;
}

/* CTA Button */
.intro .body > a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 1rem 2.5rem;
    background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
    color: white;
    font-weight: 700;
    border-radius: var(--radius-full);
    font-size: 1.125rem;
    box-shadow: var(--shadow-glow);
    transform: translateY(0);
    position: relative;
    overflow: hidden;
    z-index: 1;
}

.intro .body > a::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: linear-gradient(90deg, var(--color-accent), var(--color-primary));
    z-index: -1;
    transition: opacity 0.4s ease;
    opacity: 0;
}

.intro .body > a:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 25px rgba(139, 92, 246, 0.5);
}

.intro .body > a:hover::before {
    opacity: 1;
}

.intro .body > a:active {
    transform: translateY(-1px);
}

/* =========================================
   5. CONTENT SECTION
   ========================================= */
.content {
    background: var(--color-bg-main);
    color: var(--color-text-muted);
    font-size: 1rem;
}

.content h2 {
    font-size: var(--font-size-h2);
    color: var(--color-text-main);
    margin: var(--spacing-lg) 0 var(--spacing-sm);
    font-weight: 800;
    line-height: 1.2;
    position: relative;
}

.content h2 span {
    color: var(--color-primary);
}

.content h3 {
    font-size: var(--font-size-h3);
    color: var(--color-text-main);
    margin: var(--spacing-md) 0 var(--spacing-xs);
    font-weight: 700;
}

.content p {
    margin-bottom: 1.5rem;
    line-height: 1.75;
}

.content p strong {
    color: var(--color-text-main);
    font-weight: 600;
}

/* Lists styling inside content */
.content ul, 
.content ol {
    margin-bottom: 1.5rem;
    padding-left: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.content ul li {
    position: relative;
    padding-left: 1.5rem;
}

.content ul li::before {
    content: '➔';
    position: absolute;
    left: 0;
    color: var(--color-accent);
    font-weight: bold;
    font-size: 0.8em;
    top: 0.2em;
}

.content ol {
    counter-reset: item;
}

.content ol li {
    counter-increment: item;
    position: relative;
    padding-left: 2rem;
}

.content ol li::before {
    content: counter(item);
    position: absolute;
    left: 0;
    top: 0;
    width: 1.5rem;
    height: 1.5rem;
    background: rgba(59, 130, 246, 0.1);
    color: var(--color-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: 700;
    border: 1px solid rgba(59, 130, 246, 0.3);
}

/* Links inside content text */
.content a:not(.intro a) {
    color: var(--color-primary);
    border-bottom: 1px solid rgba(59, 130, 246, 0.3);
    transition: var(--transition-base);
}

.content a:not(.intro a):hover {
    color: var(--color-accent-glow);
    border-bottom-color: var(--color-accent-glow);
}

/* Highlight blocks for important info */
.content p:has(strong) {
    background: rgba(255, 255, 255, 0.02);
    padding: 1.5rem;
    border-radius: var(--radius-md);
    border-left: 4px solid var(--color-accent);
}

/* =========================================
   6. FOOTER
   ========================================= */
footer {
    background: var(--color-bg-secondary);
    padding: var(--spacing-lg) 0;
    margin-top: auto;
    border-top: 1px solid var(--color-border);
}

footer nav {
    flex-direction: column;
    gap: var(--spacing-md);
    margin-bottom: 0;
}

footer .logo:empty::after {
    filter: grayscale(1);
    opacity: 0.7;
}

footer ul {
    background: transparent;
    border: none;
    flex-wrap: wrap;
    justify-content: center;
}

footer ul li a {
    color: var(--color-text-muted);
    font-size: 0.9rem;
}

footer ul li a:hover {
    color: var(--color-primary);
}

/* =========================================
   7. ANIMATIONS
   ========================================= */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* =========================================
   8. MEDIA QUERIES (RESPONSIVE)
   ========================================= */

@media (max-width: 992px) {
    .intro .body {
        align-items: center;
        text-align: center;
        margin: 0 auto;
    }
    
    .intro p {
        margin: 0 auto var(--spacing-md);
    }
}

@media (max-width: 768px) {
    :root {
        --spacing-lg: 3rem;
        --spacing-md: 1.5rem;
    }

    nav {
        flex-wrap: wrap;
    }

    .burger {
        display: block;
        order: 2;
    }

    .logo {
        order: 1;
    }

    /* Mobile Menu Logic: 
       Normally requires JS to toggle class, 
       but for CSS-only robustness, we style it cleanly
    */
    nav ul {
        order: 3;
        width: 100%;
        flex-direction: column;
        margin-top: 1rem;
        background: var(--color-bg-card);
        border-radius: var(--radius-md);
        display: none; /* JS would toggle this to flex */
    }

    /* If no JS is present, let's allow it to be visible if the user strictly follows the prompt's input HTML which lacks checkbox hack structure */
    /* Alternative: Stack links under logo for mobile if menu logic isn't active */
    nav ul {
        display: flex;
        gap: 0.5rem;
        padding: 1rem;
    }

    nav ul li {
        width: 100%;
        text-align: center;
    }
    
    nav ul li a {
        display: block;
        padding: 0.5rem;
        background: rgba(255,255,255,0.02);
        border-radius: var(--radius-sm);
    }

    .intro h1 {
        font-size: 2.5rem;
    }
    
    .content {
        padding-top: var(--spacing-md);
    }
    
    .content h2 {
        font-size: 1.75rem;
    }
    
    .content ul, .content ol {
        padding-left: 0.5rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }

    .intro .body > a {
        width: 100%;
    }
    
    nav ul {
        display: none; /* Hide nav on very small screens if no JS, or assume JS toggles */
    }
    
    /* Fallback if JS adds 'active' class to nav */
    nav.active ul {
        display: flex;
    }
}