/* ReThink.fast Landing Page Styles */

/* CSS Variables - Chess Theme */
:root {
    --black: #1a1a1a;
    --white: #f5f5f5;
    --gold: #d4af37;
    --grey-dark: #2d2d2d;
    --grey-mid: #4a4a4a;
    --grey-light: #d0d0d0;
    --accent: #d4af37;

    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;

    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Reset & Base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-main);
    background: var(--black);
    color: var(--white);
    line-height: 1.6;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: transparent;
    backdrop-filter: blur(0px);
    border-bottom: 1px solid transparent;
    z-index: 1000;
    padding: 1.5rem 0;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.navbar.scrolled {
    background: rgba(26, 26, 26, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(212, 175, 55, 0.1);
    padding: 0.75rem 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-text {
    font-size: 1.75rem;
    font-weight: 800;
    color: var(--gold);
    letter-spacing: -0.5px;
}

.logo-img {
    height: 50px;
    width: auto;
    transition: height 0.3s ease;
}

.navbar.scrolled .logo-img {
    height: 40px;
}

.logo-img-small {
    height: 40px;
    width: auto;
}

.nav-links {
    display: flex;
    gap: 1rem;
    align-items: center;
}

/* Default Link Style (Base) */
.nav-links a {
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
    font-size: 0.95rem;
}

/* Initial State (Top): White Rounded Buttons for ALL links */
.navbar:not(.scrolled) .nav-links a {
    color: var(--white);
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.3);
    padding: 0.6rem 1.2rem;
    border-radius: 50px;
    backdrop-filter: blur(5px);
}

.navbar:not(.scrolled) .nav-links a:hover {
    background: var(--white);
    color: var(--black);
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
}

/* Specific style for Log In button in initial state */
.navbar:not(.scrolled) .nav-links a.nav-cta {
    background: var(--white);
    color: var(--black);
    border-color: var(--white);
    font-weight: 600;
}

.navbar:not(.scrolled) .nav-links a.nav-cta:hover {
    background: var(--gold);
    border-color: var(--gold);
    color: var(--black);
    box-shadow: 0 4px 15px rgba(212, 175, 55, 0.4);
}

/* Scrolled State: Text Links for ALL links */
.navbar.scrolled .nav-links a {
    color: var(--grey-light);
    padding: 0.5rem;
    border: none;
    background: transparent;
}

.navbar.scrolled .nav-links a:hover {
    color: var(--white);
}

/* Mobile Menu Button */
.mobile-menu-btn {
    display: none;
    font-size: 1.5rem;
    color: var(--white);
    cursor: pointer;
    z-index: 1001;
}

/* Hero Section */
.hero-section {
    position: relative;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.visualization-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
    pointer-events: none;
    /* Changed to none to allow mouse tracking in parent */
    z-index: 0;
}

.hero-content {
    position: relative;
    z-index: 10;
    text-align: center;
    max-width: 900px;
    padding: 2rem;
    pointer-events: none;
}

.hero-content * {
    pointer-events: auto;
}

.hero-content-lower {
    transform: translateY(230px);
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--grey-light);
    margin-bottom: 2.5rem;
    font-weight: 300;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.8);
}

.hero-buttons {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    padding: 1rem 2rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    font-size: 1.1rem;
    transition: var(--transition);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: var(--gold);
    color: var(--black);
    box-shadow: 0 4px 20px rgba(212, 175, 55, 0.3);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 30px rgba(212, 175, 55, 0.5);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: var(--white);
    border: 2px solid rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.15);
    border-color: var(--gold);
}

/* Unified Section Navigation Arrow (Circle Style) */
.section-arrow,
.section-arrow-circle {
    position: absolute;
    top: 50%;
    /* Vertically center in section */
    transform: translateY(-50%);
    /* Offset for perfect centering */
    left: 4rem;
    /* Left side positioning */

    width: 60px;
    height: 60px;
    border-radius: 50%;

    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(212, 175, 55, 0.3);
    backdrop-filter: blur(5px);

    display: flex;
    align-items: center;
    justify-content: center;

    color: var(--gold);
    font-size: 1.5rem;
    text-decoration: none;

    transition: all 0.3s ease;
    z-index: 20;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
}

.section-arrow:hover,
.section-arrow-circle:hover {
    background: var(--gold);
    color: var(--black);
    transform: translateY(-50%) translateY(-5px);
    /* Maintain centering while lifting */
    box-shadow: 0 8px 25px rgba(212, 175, 55, 0.4);
    border-color: var(--gold);
}

/* Bounce animation for the icon inside */
.section-arrow i,
.section-arrow-circle i {
    animation: simple-bounce 2s infinite;
}

@keyframes simple-bounce {

    0%,
    20%,
    50%,
    80%,
    100% {
        transform: translateY(0);
    }

    40% {
        transform: translateY(-3px);
    }

    60% {
        transform: translateY(-1.5px);
    }
}

@keyframes bounce {
    /* Removing old bounce to avoid conflict */
}

/* Up arrow variant - positioned on the right */
.section-arrow-up {
    left: auto;
    right: 4rem;
    /* Mirror position on the right */
}

/* Features Section - Modern Glassmorphism & Bento Grid */
/* Features Section - Modern Glassmorphism & Bento Grid */
.features-section {
    position: relative;
    padding: 1rem 0;
    /* Significantly reduced to allow 100vh fit */
    overflow: hidden;
    background: radial-gradient(circle at 50% 50%, #1a1a1a 0%, #0d0d0d 100%);
    scroll-margin-top: 0;

    /* Enforce One Page / Fullscreen feel */
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

/* Background glow effect behind features */
.features-section::before {
    content: '';
    position: absolute;
    top: 20%;
    left: 10%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(212, 175, 55, 0.08) 0%, transparent 70%);
    filter: blur(80px);
    pointer-events: none;
    z-index: 0;
    animation: flowBlob 20s infinite alternate ease-in-out;
}

.features-section::after {
    content: '';
    position: absolute;
    bottom: 10%;
    right: 5%;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(142, 68, 173, 0.08) 0%, transparent 70%);
    filter: blur(80px);
    pointer-events: none;
    z-index: 0;
    animation: flowBlob 25s infinite alternate-reverse ease-in-out;
}

@keyframes flowBlob {
    0% {
        transform: translate(0, 0) scale(1);
    }

    100% {
        transform: translate(30px, -30px) scale(1.1);
    }
}

.section-title {
    font-size: 2.5rem;
    /* Slightly smaller */
    font-weight: 800;
    text-align: center;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, #fff 20%, #888 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -1.5px;
    position: relative;
    z-index: 10;
}

.section-subtitle {
    font-size: 1.1rem;
    color: var(--grey-light);
    margin-bottom: 1.5rem;
    /* Reduced from 4rem */
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
    text-align: center;
    position: relative;
    z-index: 10;
    opacity: 0.8;
}

/* Bento Grid Layout */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    /* Default to 3 equal columns */
    gap: 1rem;
    /* Reduced gap */
    position: relative;
    z-index: 10;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    width: 100%;
}

/* Card Styling - Deep Glassmorphism */
.feature-card {
    background: rgba(20, 20, 20, 0.6);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    padding: 1.25rem;
    /* Reduced from 2.5rem */
    border-radius: 20px;
    border: 1px solid rgba(255, 255, 255, 0.08);
    /* More subtle border */
    transition: all 0.4s cubic-bezier(0.25, 0.8, 0.25, 1);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    text-align: left;
    height: 100%;
    /* Ensure cards fill grid cell height */
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
}

/* Span classes for Bento layout */
.feature-span-2 {
    grid-column: span 2;
}

/* Hover Effects */
.feature-card:hover {
    transform: translateY(-5px);
    background: rgba(30, 30, 30, 0.7);
    border-color: rgba(255, 255, 255, 0.15);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.4), 0 0 20px rgba(255, 255, 255, 0.05) inset;
}

/* Spotlight/Glow Effect on Hover */
.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(800px circle at var(--mouse-x, 50%) var(--mouse-y, 50%), rgba(255, 255, 255, 0.06), transparent 40%);
    opacity: 0;
    transition: opacity 0.5s;
    pointer-events: none;
    z-index: -1;
}

.feature-card:hover::before {
    opacity: 1;
}

/* Icon Styling */
.feature-icon-wrapper {
    width: 48px;
    height: 48px;
    border-radius: 12px;
    background: rgba(255, 255, 255, 0.05);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 0.75rem;
    border: 1px solid rgba(255, 255, 255, 0.05);
    transition: all 0.3s ease;
}

.feature-card:hover .feature-icon-wrapper {
    background: rgba(255, 255, 255, 0.1);
    transform: scale(1.05);
}

.feature-icon {
    font-size: 1.4rem;
    color: var(--white);
    /* Default to white/neutral */
    transition: all 0.3s ease;
}

/* Typography in Cards */
.feature-card h3 {
    margin-bottom: 0.5rem;
    color: var(--white);
    font-weight: 700;
    font-size: 1.2rem;
    letter-spacing: -0.5px;
}

.feature-card p {
    color: #a0a0a0;
    /* Softer grey */
    line-height: 1.5;
    font-size: 0.9rem;
    font-weight: 400;
}

/* Feature Specific Accents (Subtle gradients) */
/* Rainbow Mode */
.feature-rainbow .feature-icon-wrapper {
    background: linear-gradient(135deg, rgba(255, 159, 243, 0.15) 0%, rgba(254, 202, 87, 0.15) 100%);
    border-color: rgba(255, 159, 243, 0.2);
}

.feature-rainbow .feature-icon {
    background: linear-gradient(135deg, #ff9ff3 0%, #feca57 100%);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Maia */
.feature-maia .feature-icon-wrapper {
    background: linear-gradient(135deg, rgba(84, 160, 255, 0.15) 0%, rgba(0, 210, 211, 0.15) 100%);
    border-color: rgba(84, 160, 255, 0.2);
}

.feature-maia .feature-icon {
    background: linear-gradient(135deg, #54a0ff 0%, #00d2d3 100%);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Threats */
.feature-threats .feature-icon-wrapper {
    background: linear-gradient(135deg, rgba(255, 107, 107, 0.15) 0%, rgba(238, 82, 83, 0.15) 100%);
    border-color: rgba(255, 107, 107, 0.2);
}

.feature-threats .feature-icon {
    background: linear-gradient(135deg, #ff6b6b 0%, #ee5253 100%);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Concepts */
.feature-concepts .feature-icon-wrapper {
    background: linear-gradient(135deg, rgba(162, 155, 254, 0.15) 0%, rgba(108, 92, 231, 0.15) 100%);
    border-color: rgba(162, 155, 254, 0.2);
}

.feature-concepts .feature-icon {
    background: linear-gradient(135deg, #a29bfe 0%, #6c5ce7 100%);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Openings (Gold) */
.feature-openings .feature-icon-wrapper {
    background: linear-gradient(135deg, rgba(212, 175, 55, 0.15) 0%, rgba(255, 223, 0, 0.1) 100%);
    border-color: rgba(212, 175, 55, 0.2);
}

.feature-openings .feature-icon {
    background: linear-gradient(135deg, #d4af37 0%, #f1c40f 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Analytics (Green) */
.feature-analytics .feature-icon-wrapper {
    background: linear-gradient(135deg, rgba(29, 209, 161, 0.15) 0%, rgba(16, 172, 132, 0.15) 100%);
    border-color: rgba(29, 209, 161, 0.2);
}

.feature-analytics .feature-icon {
    background: linear-gradient(135deg, #1dd1a1 0%, #10ac84 100%);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}


/* Responsive adjustments for Bento Grid */
@media (max-width: 900px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .feature-span-2 {
        grid-column: span 2;
        /* Keep distinct span on tablet */
    }

    /* Analytics fits better as 1 col on tablet (paired with Openings) */
    .feature-analytics.feature-span-2 {
        grid-column: span 1;
    }
}

@media (max-width: 768px) {
    .features-grid {
        grid-template-columns: 1fr;
        /* Single column on mobile/tablet portrait */
    }

    .feature-span-2 {
        grid-column: span 1;
        /* Reset span on mobile */
    }

    .feature-analytics.feature-span-2 {
        grid-column: span 1;
    }

    .feature-card {
        padding: 2rem;
    }

    .section-title {
        font-size: 2.2rem;
    }

    /* Hide section navigation arrows on mobile */
    .section-arrow,
    .section-arrow-up,
    .section-arrow-circle,
    .scroll-indicator {
        display: none !important;
    }

    /* Hero adjustments for mobile */
    .hero-content-lower {
        transform: translateY(100px);
    }

    .hero-subtitle {
        font-size: 1.1rem;
    }

    .hero-buttons {
        flex-direction: column;
        gap: 1rem;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }

    /* Hide visualization iframe completely on mobile */
    .visualization-background,
    .cta-background {
        display: none !important;
    }

    /* Show mobile logo in hero section */
    .hero-mobile-logo {
        display: block !important;
        max-width: 200px;
        height: auto;
        margin: 0 auto 1.5rem auto;
        filter: drop-shadow(0 4px 20px rgba(212, 175, 55, 0.5));
        animation: logo-pulse 3s ease-in-out infinite;
    }

    @keyframes logo-pulse {

        0%,
        100% {
            transform: scale(1);
            filter: drop-shadow(0 4px 20px rgba(212, 175, 55, 0.5));
        }

        50% {
            transform: scale(1.05);
            filter: drop-shadow(0 8px 30px rgba(212, 175, 55, 0.7));
        }
    }

    /* Adjust hero content positioning for mobile - centered vertically */
    .hero-content-lower {
        transform: translateY(-50%);
        position: absolute;
        top: 50%;
        left: 0;
        right: 0;
        padding: 0 20px;
    }


    .hero-section {
        background: radial-gradient(ellipse at center, #1a1a1a 0%, #0a0a0a 100%);
    }
}

/* Default: Hide mobile logo on desktop */
.hero-mobile-logo {
    display: none;
}



/* About Section */
.about-section {
    padding: 0;
    /* Removing padding to let flex center it */
    min-height: 100vh;
    /* Full screen height */
    background: var(--black);
    display: flex;
    align-items: center;
    position: relative;
    z-index: 5;
    /* Ensure it sits above CTA background overlap if any */
}

.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    padding: 4rem 0;
    /* Add internal padding instead */
}

/* Adjust arrows in About section (shift up by 80px) */
.about-section .section-arrow {
    top: calc(50% - 80px);
}

.about-content p {
    font-size: 1.125rem;
    color: var(--grey-light);
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

.about-features {
    list-style: none;
    margin-top: 2rem;
}

.about-features li {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.75rem 0;
    font-size: 1.125rem;
}

.about-features i {
    color: var(--gold);
    font-size: 1.25rem;
}

.about-visual {
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    /* Optional: Add a subtle glow behind the image */
}

.about-visual::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 80%;
    height: 80%;
    background: radial-gradient(circle, rgba(212, 175, 55, 0.15) 0%, transparent 70%);
    filter: blur(60px);
    z-index: -1;
}

.about-img {
    max-width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.5), 0 0 0 1px rgba(255, 255, 255, 0.1);
    transition: transform 0.5s ease;
}

.about-img:hover {
    transform: scale(1.02);
}

/* CTA Section */
.cta-section {
    padding: 6rem 0;
    /* background: var(--grey-dark); */
    /* Removed to let canvas be the background */
    text-align: center;
    position: relative;
    overflow: hidden;
}

.cta-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    border: none;
    /* opacity: 0.6; */
    /* Removed to make it fully visible like hero section */
}

.cta-section .container {
    position: relative;
    z-index: 1;
    pointer-events: none;
    /* Let mouse pass through container to canvas where possible? No, buttons need clicks */
}

.cta-section .container>* {
    pointer-events: auto;
    /* Re-enable pointer events for content elements */
}

.cta-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.cta-subtitle {
    font-size: 1.25rem;
    color: var(--grey-light);
    margin-bottom: 3rem;
}

.cta-buttons {
    margin-bottom: 2rem;
}

.btn-large {
    padding: 1.25rem 3rem;
    font-size: 1.25rem;
}

.cta-note {
    color: var(--grey-light);
    font-size: 0.95rem;
}

/* Footer */
.footer {
    background: var(--black);
    padding: 4rem 0 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 4rem;
    margin-bottom: 3rem;
}

.footer-brand p {
    color: var(--grey-light);
    margin-top: 1rem;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.footer-links {
    display: flex;
    gap: 3rem;
}

.footer-column h4 {
    margin-bottom: 1rem;
    color: var(--white);
}

.footer-column a {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--grey-light);
    text-decoration: none;
    margin-bottom: 0.75rem;
    transition: var(--transition);
}

.footer-column a:hover {
    color: var(--gold);
    transform: translateX(5px);
}

.footer-column a i {
    margin-right: 0;
    width: 1.5rem;
    text-align: center;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    color: var(--grey-light);
}

/* Responsive Design */
@media (max-width: 1024px) {
    .about-grid {
        grid-template-columns: 1fr;
        gap: 3rem;
    }

    .chess-pattern {
        width: 300px;
        height: 300px;
    }

    .chess-pattern i {
        font-size: 7rem;
    }
}

@media (max-width: 768px) {
    .mobile-menu-btn {
        display: block;
    }

    .nav-links {
        position: fixed;
        top: 0;
        right: -100%;
        width: 100%;
        height: 100vh;
        background: rgba(26, 26, 26, 0.98);
        backdrop-filter: blur(10px);
        flex-direction: column;
        justify-content: center;
        gap: 2rem;
        transition: right 0.3s ease;
        z-index: 1000;
    }

    .nav-links.active {
        right: 0;
    }

    .nav-links a {
        font-size: 1.5rem;
    }

    /* Reset button styles for mobile to be clean text */
    .navbar:not(.scrolled) .nav-links a,
    .navbar.scrolled .nav-links a {
        background: transparent;
        border: none;
        color: var(--white);
        padding: 1rem;
        font-size: 1.5rem;
    }

    .hero-subtitle {
        font-size: 1.25rem;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .section-title {
        font-size: 2.25rem;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .footer-links {
        gap: 2rem;
    }
}

@media (max-width: 480px) {
    .hero-subtitle {
        font-size: 1.1rem;
    }

    .container {
        padding: 0 1.5rem;
    }

    .logo-text {
        font-size: 1.5rem;
    }

    .chess-pattern {
        width: 250px;
        height: 250px;
    }
}

/* Interactive Text Style */
.interactive-text {
    cursor: pointer;
    transition: all 0.3s ease;
    border-radius: 50px;
    padding: 2px 8px;
    border: 1px solid transparent;
    user-select: none;
    -webkit-user-select: none;
}

.interactive-text:hover {
    border: 1px solid rgba(255, 255, 255, 0.3);
    background: rgba(255, 255, 255, 0.1);
    box-shadow: 0 0 10px rgba(255, 255, 255, 0.1);
}

/* Utility for accessibility/SEO */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}