/* =========================================
   1. Reset & Base Configuration
   ========================================= */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    /* Color Palette */
    --color-bg-body: #0f172a;
    --color-bg-card: #1e293b;
    --color-bg-darker: #020617;
    
    --color-primary: #3b82f6;
    --color-primary-dark: #2563eb;
    --color-accent: #8b5cf6;
    --color-accent-gradient: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 100%);
    
    --color-text-main: #f8fafc;
    --color-text-muted: #94a3b8;
    --color-success: #10b981;
    --color-highlight: #fbbf24;

    /* Typography */
    --font-family-base: system-ui, -apple-system, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --font-size-base: 1rem;
    --line-height-base: 1.6;

    /* Spacing & Sizes */
    --container-width: 1200px;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 2rem;
    --spacing-xl: 4rem;
    --border-radius-sm: 0.5rem;
    --border-radius-lg: 1rem;
    --border-radius-pill: 50rem;

    /* Effects */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-neon: 0 0 15px rgba(59, 130, 246, 0.5);
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: var(--font-family-base);
    background-color: var(--color-bg-body);
    color: var(--color-text-main);
    line-height: var(--line-height-base);
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

/* =========================================
   2. Layout Utilities
   ========================================= */
.container {
    width: 100%;
    max-width: var(--container-width);
    margin: 0 auto;
    padding-left: var(--spacing-md);
    padding-right: var(--spacing-md);
}

.row-center {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
}

.text-center {
    text-align: center;
}

.col-xs-12 {
    width: 100%;
    max-width: 800px; /* Optimal reading width */
    margin: 0 auto;
}

/* =========================================
   3. Top Navigation (Mobile/Header)
   ========================================= */
.line-menu-mobile {
    padding: var(--spacing-md) 0;
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.line-menu-mobile .row-center {
    justify-content: flex-end;
    gap: var(--spacing-md);
}

.landing-header-right-login,
.landing-header-right-reg {
    padding: 0.5rem 1.25rem;
    border-radius: var(--border-radius-sm);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition-normal);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.landing-header-right-login {
    color: var(--color-text-main);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.landing-header-right-login:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--color-text-main);
}

.landing-header-right-reg {
    background: var(--color-success);
    color: #fff;
    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.3);
}

.landing-header-right-reg:hover {
    background: #059669;
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(16, 185, 129, 0.4);
}

/* =========================================
   4. Hero Section (.header-box)
   ========================================= */
.header-box {
    position: relative;
    padding: var(--spacing-xl) 0;
    background: radial-gradient(circle at top center, #1e293b 0%, #0f172a 70%);
    overflow: hidden;
}

/* Background visual decoration */
.header-box::before {
    content: '';
    position: absolute;
    top: -50%;
    left: 50%;
    transform: translateX(-50%);
    width: 100%;
    height: 200%;
    background: radial-gradient(circle, rgba(59, 130, 246, 0.15) 0%, transparent 50%);
    pointer-events: none;
    z-index: 0;
}

.header-box .table {
    display: flex;
    justify-content: center;
    position: relative;
    z-index: 1;
}

.ctr {
    max-width: 800px;
    width: 100%;
    padding: 0 var(--spacing-md);
    animation: fadeInUp 0.8s ease-out;
}

.header-box h1 {
    font-size: clamp(2rem, 5vw, 4rem);
    font-weight: 800;
    text-align: center;
    margin-bottom: var(--spacing-lg);
    line-height: 1.1;
    background: linear-gradient(to right, #fff, #94a3b8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
}

.text-head {
    font-size: 1.1rem;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-lg);
}

.text-head b {
    color: var(--color-highlight);
    font-weight: 700;
}

/* Promo Code Styling */
.promo {
    display: inline-block;
    background: rgba(255, 255, 255, 0.1);
    padding: 0.25rem 0.75rem;
    border: 1px dashed var(--color-highlight);
    color: var(--color-highlight);
    font-family: monospace;
    font-size: 1.2em;
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: var(--transition-fast);
    position: relative;
}

.promo:hover {
    background: rgba(251, 191, 36, 0.1);
    transform: scale(1.05);
}

.promo::after {
    content: 'Click to copy';
    position: absolute;
    bottom: 120%;
    left: 50%;
    transform: translateX(-50%);
    background: #000;
    color: #fff;
    font-size: 0.75rem;
    padding: 4px 8px;
    border-radius: 4px;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.2s;
    white-space: nowrap;
    font-family: var(--font-family-base);
}

.promo:hover::after {
    opacity: 1;
    visibility: visible;
}

.inform-promo {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-top: var(--spacing-sm);
    opacity: 0.7;
}

/* =========================================
   5. Buttons (Global & Hero)
   ========================================= */
.button {
    display: inline-flex;
    justify-content: center;
    align-items: center;
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    font-weight: 700;
    color: white;
    background: var(--color-accent-gradient);
    border-radius: var(--border-radius-pill);
    cursor: pointer;
    transition: var(--transition-normal);
    box-shadow: 0 10px 20px -5px rgba(59, 130, 246, 0.4);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    position: relative;
    overflow: hidden;
    user-select: none;
    text-decoration: none;
}

.button::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(rgba(255, 255, 255, 0.2), transparent);
    opacity: 0;
    transition: opacity 0.3s;
}

.button:hover {
    transform: translateY(-3px) scale(1.02);
    box-shadow: 0 15px 30px -5px rgba(139, 92, 246, 0.5);
}

.button:hover::before {
    opacity: 1;
}

.button:active {
    transform: translateY(-1px);
}

/* =========================================
   6. Content Section
   ========================================= */
.content {
    padding: var(--spacing-xl) 0;
    background-color: var(--color-bg-body);
}

.content h2 {
    font-size: clamp(1.5rem, 3vw, 2.2rem);
    color: var(--color-text-main);
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
    font-weight: 700;
    position: relative;
    padding-left: 1rem;
    border-left: 4px solid var(--color-primary);
}

.content p {
    margin-bottom: var(--spacing-md);
    color: var(--color-text-muted);
    font-size: 1.05rem;
    text-align: justify;
}

.content ul {
    margin-bottom: var(--spacing-lg);
    padding-left: 0;
    list-style: none;
}

.content ul li {
    position: relative;
    padding-left: 2rem;
    margin-bottom: 0.75rem;
    color: var(--color-text-main);
    font-size: 1.05rem;
}

.content ul li::before {
    content: '✓';
    position: absolute;
    left: 0;
    top: 2px;
    color: var(--color-success);
    font-weight: bold;
    font-size: 1.2rem;
}

.content ul ul {
    margin-top: 0.5rem;
    margin-bottom: 0.5rem;
    border-left: 1px solid rgba(255, 255, 255, 0.1);
    margin-left: 1rem;
    padding-left: 1rem;
}

.content ul ul li::before {
    content: '•';
    color: var(--color-primary);
    font-size: 1.5rem;
    top: -5px;
}

/* Images in content */
.content .img {
    margin: var(--spacing-lg) 0;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    position: relative;
    background: var(--color-bg-card);
}

.content .img img {
    display: block;
    width: 100%;
    height: auto;
    object-fit: cover;
    transition: transform 0.5s ease;
}

.content .img:hover img {
    transform: scale(1.03);
}

/* CTA inside content */
.content .text-center {
    margin: var(--spacing-lg) 0;
}

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

/* Lazyload placeholder fade */
img[data-src] {
    opacity: 0;
    transition: opacity 0.3s;
}

img.loaded {
    opacity: 1;
}

/* =========================================
   8. Responsive Design
   ========================================= */
@media (max-width: 768px) {
    :root {
        --spacing-xl: 2.5rem;
    }

    .line-menu-mobile .row-center {
        justify-content: space-between;
        padding: 0 var(--spacing-md);
    }
    
    .landing-header-right-login, 
    .landing-header-right-reg {
        padding: 0.4rem 0.8rem;
        font-size: 0.8rem;
    }

    .header-box h1 {
        margin-bottom: var(--spacing-md);
    }
    
    .content h2 {
        margin-top: var(--spacing-lg);
        font-size: 1.5rem;
    }

    .button {
        width: 100%;
        max-width: 320px;
        padding: 0.8rem 1.5rem;
    }
}

/* =========================================
   9. Form Elements (Generic preparation)
   ========================================= */
input, select, textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    background: var(--color-bg-card);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--border-radius-sm);
    color: var(--color-text-main);
    font-family: inherit;
    transition: var(--transition-fast);
}

input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

/* Checkbox/Radio specific styles if added later */
input[type="checkbox"], input[type="radio"] {
    width: auto;
    margin-right: 0.5rem;
    accent-color: var(--color-primary);
}