/*
Theme Name: AI Boom List
Theme URI: https://aiboomlist.com/
Author: Antigravity Custom Themes
Author URI: https://aiboomlist.com/
Description: A premium, zero-plugin, fast and beautiful custom WordPress theme for AI tools directory and tech blogs. Completely self-contained with built-in SEO and contact processing.
Version: 1.0.0
License: GNU General Public License v2 or later
License URI: http://www.gnu.org/licenses/gpl-2.0.html
Text Domain: aiboomlist
Tags: dark, one-column, grid-layout, custom-menu, featured-images, translation-ready
*/

/* ==========================================================================
   AI Boom List - Modern Visual Design System
   ========================================================================== */

/* Google Fonts Import */
@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@300;400;500;600;700;800&family=Space+Grotesk:wght@400;500;600;700&display=swap');

/* CSS Variables for Clean Design Token System */
:root {
    --bg-main: #080b11;
    --bg-card: rgba(17, 24, 39, 0.6);
    --bg-card-hover: rgba(26, 36, 56, 0.8);
    --border-color: rgba(255, 255, 255, 0.08);
    --border-hover: rgba(99, 102, 241, 0.4);
    
    --primary-glow: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
    --secondary-glow: linear-gradient(135deg, #06b6d4 0%, #3b82f6 100%);
    --text-glow: linear-gradient(135deg, #ffffff 0%, #cbd5e1 100%);
    
    --color-primary: #6366f1;
    --color-secondary: #06b6d4;
    --color-accent: #a855f7;
    --color-text-main: #f3f4f6;
    --color-text-muted: #9ca3af;
    --color-text-dark: #6b7280;
    
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.5);
    --shadow-md: 0 8px 30px rgba(0, 0, 0, 0.7);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.15);
    
    --font-heading: 'Space Grotesk', sans-serif;
    --font-body: 'Plus Jakarta Sans', sans-serif;
    
    --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --border-radius-sm: 8px;
    --border-radius-md: 16px;
    --border-radius-lg: 24px;
}

/* Base Resets & Global Styles */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

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

body {
    background-color: var(--bg-main);
    color: var(--color-text-main);
    font-family: var(--font-body);
    line-height: 1.6;
    overflow-x: hidden;
    position: relative;
}

/* Background Glowing Blobs for Premium Aesthetic */
body::before, body::after {
    content: '';
    position: fixed;
    width: 400px;
    height: 400px;
    border-radius: 50%;
    filter: blur(120px);
    z-index: -1;
    opacity: 0.12;
    pointer-events: none;
}

body::before {
    top: 15vh;
    left: -100px;
    background: var(--color-primary);
}

body::after {
    top: 55vh;
    right: -100px;
    background: var(--color-accent);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: -0.02em;
}

h1 {
    font-size: clamp(2rem, 5vw, 2.75rem);
    margin-bottom: 1.5rem;
    background: var(--text-glow);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

h2 {
    font-size: clamp(1.5rem, 4vw, 2rem);
    margin-bottom: 1.25rem;
}

p {
    color: var(--color-text-muted);
    font-weight: 400;
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: var(--transition-smooth);
}

a:hover {
    color: var(--color-accent);
}

ul {
    list-style: none;
}

/* Header & Navigation */
.navbar {
    width: 100%;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    background-color: rgba(8, 11, 17, 0.8);
    border-bottom: 1px solid var(--border-color);
}

.navbar-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.25rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-text-main);
}

.logo span {
    background: var(--primary-glow);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-links ul {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-link, .nav-links ul li a {
    color: var(--color-text-muted);
    font-weight: 500;
    font-size: 0.95rem;
    transition: var(--transition-smooth);
}

.nav-link:hover, .nav-links ul li a:hover,
.nav-link.active, .nav-links ul li.current-menu-item a {
    color: var(--color-text-main);
    text-shadow: 0 0 10px rgba(255, 255, 255, 0.3);
}

.btn-primary {
    background: var(--primary-glow);
    color: #ffffff !important;
    padding: 0.6rem 1.25rem;
    border-radius: var(--border-radius-sm);
    font-weight: 600;
    font-size: 0.9rem;
    border: none;
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    transition: var(--transition-smooth);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
}

/* Mobile Toggle Hamburger Button (hidden on desktop) */
.nav-toggle {
    display: none;
}

/* Hero Section */
.hero {
    max-width: 1200px;
    margin: 0 auto;
    padding: 5rem 2rem 3.5rem 2rem;
    text-align: center;
    position: relative;
}

.hero-subtitle {
    font-family: var(--font-heading);
    text-transform: uppercase;
    font-size: 0.85rem;
    letter-spacing: 0.15em;
    color: var(--color-secondary);
    margin-bottom: 1rem;
    font-weight: 600;
}

.hero p {
    font-size: 1.15rem;
    max-width: 600px;
    margin: 0 auto 2.5rem auto;
}

.search-box {
    max-width: 600px;
    margin: 0 auto 2rem auto;
    position: relative;
    border-radius: var(--border-radius-md);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    padding: 0.35rem;
    display: flex;
    transition: var(--transition-smooth);
}

.search-box:focus-within {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-glow);
}

.search-box input {
    background: transparent;
    border: none;
    outline: none;
    color: var(--color-text-main);
    padding: 0.75rem 1rem;
    font-size: 1rem;
    flex-grow: 1;
    width: 100%;
}

.search-box button {
    background: var(--primary-glow);
    border: none;
    border-radius: var(--border-radius-sm);
    padding: 0.75rem 1.5rem;
    color: white;
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition-smooth);
}

.search-box button:hover {
    opacity: 0.9;
}

/* Directory Section */
.directory-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem 5rem 2rem;
}

.filter-bar {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 2.5rem;
    justify-content: center;
    flex-wrap: wrap;
}

.filter-btn {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    color: var(--color-text-muted);
    padding: 0.5rem 1.25rem;
    border-radius: 30px;
    cursor: pointer;
    font-weight: 500;
    font-size: 0.9rem;
    font-family: var(--font-body);
    transition: var(--transition-smooth);
}

.filter-btn:hover, .filter-btn.active {
    border-color: var(--color-primary);
    color: var(--color-text-main);
    background: rgba(99, 102, 241, 0.1);
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(min(100%, 300px), 1fr));
    gap: 2rem;
}

.tool-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 1.75rem;
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
    height: 100%;
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(8px);
}

.tool-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background: var(--primary-glow);
    opacity: 0;
    transition: var(--transition-smooth);
}

.tool-card:hover {
    transform: translateY(-5px);
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
    box-shadow: var(--shadow-md);
}

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

.tool-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1.25rem;
}

.tool-icon {
    width: 48px;
    height: 48px;
    border-radius: 12px;
    background: rgba(255, 255, 255, 0.05);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.tool-pricing {
    font-size: 0.75rem;
    font-weight: 700;
    padding: 0.25rem 0.6rem;
    border-radius: 30px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.pricing-free {
    background: rgba(16, 185, 129, 0.1);
    color: #10b981;
    border: 1px solid rgba(16, 185, 129, 0.2);
}

.pricing-freemium {
    background: rgba(245, 158, 11, 0.1);
    color: #f59e0b;
    border: 1px solid rgba(245, 158, 11, 0.2);
}

.pricing-paid {
    background: rgba(99, 102, 241, 0.1);
    color: #818cf8;
    border: 1px solid rgba(99, 102, 241, 0.2);
}

.tool-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--color-text-main);
}

.tool-title a {
    color: var(--color-text-main);
}

.tool-title a:hover {
    color: var(--color-primary);
}

.tool-category-badge {
    font-size: 0.75rem;
    color: var(--color-secondary);
    text-transform: uppercase;
    font-weight: 600;
    letter-spacing: 0.05em;
    margin-bottom: 1rem;
}

.tool-description {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.tool-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    padding-top: 1rem;
    margin-top: auto;
}

.tool-rating {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    font-size: 0.85rem;
    color: var(--color-text-main);
    font-weight: 600;
}

.tool-rating span.star {
    color: #fbbf24;
}

.tool-link {
    font-size: 0.85rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.tool-link:hover {
    gap: 0.5rem;
}

/* Breadcrumbs Styling */
.breadcrumbs {
    max-width: 1200px;
    margin: 1.5rem auto 0 auto;
    padding: 0 2rem;
    font-size: 0.85rem;
    color: var(--color-text-dark);
}

.breadcrumbs a {
    color: var(--color-text-muted);
}

.breadcrumbs a:hover {
    color: var(--color-text-main);
}

.breadcrumbs span.separator {
    margin: 0 0.5rem;
    color: var(--border-color);
}

/* Blog List Section */
.blog-header {
    text-align: center;
    padding: 5rem 2rem 3rem 2rem;
    max-width: 800px;
    margin: 0 auto;
}

.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: 2.5rem;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem 5rem 2rem;
}

.blog-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    overflow: hidden;
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
    height: 100%;
}

.blog-card:hover {
    transform: translateY(-5px);
    border-color: var(--border-hover);
    background: var(--bg-card-hover);
    box-shadow: var(--shadow-md);
}

.blog-img-placeholder {
    height: 200px;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.15) 0%, rgba(168, 85, 247, 0.15) 100%);
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    border-bottom: 1px solid var(--border-color);
}

.blog-img-placeholder::after {
    content: '⚡';
    font-size: 3rem;
    opacity: 0.6;
}

.blog-content {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    flex-grow: 1;
}

.blog-meta {
    font-size: 0.75rem;
    color: var(--color-text-dark);
    margin-bottom: 0.75rem;
    display: flex;
    gap: 1rem;
}

.blog-title {
    font-size: 1.35rem;
    margin-bottom: 0.75rem;
    color: var(--color-text-main);
}

.blog-title a {
    color: var(--color-text-main);
}

.blog-title a:hover {
    color: var(--color-primary);
}

.blog-summary {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

/* Post Styling (Single Page Blog Post) */
.post-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 4rem 1.5rem 6rem 1.5rem;
}

.post-header {
    margin-bottom: 3rem;
    text-align: center;
}

.post-meta {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-bottom: 1rem;
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

.post-content {
    font-size: 1.1rem;
    line-height: 1.8;
    color: #e2e8f0;
}

.post-content h2 {
    font-size: 1.75rem;
    margin: 2.5rem 0 1rem 0;
    color: var(--color-text-main);
}

.post-content p {
    margin-bottom: 1.5rem;
}

.post-content ul, .post-content ol {
    margin-bottom: 1.5rem;
    padding-left: 1.5rem;
}

.post-content li {
    margin-bottom: 0.5rem;
}

.post-content blockquote {
    border-left: 4px solid var(--color-primary);
    background: rgba(99, 102, 241, 0.05);
    padding: 1rem 1.5rem;
    margin: 2rem 0;
    border-radius: 0 var(--border-radius-sm) var(--border-radius-sm) 0;
}

.post-content blockquote p {
    margin-bottom: 0;
    font-style: italic;
    color: #cbd5e1;
}

.post-content a {
    text-decoration: underline;
    font-weight: 500;
}

/* Single AI Tool Detail Page Layout */
.tool-detail-grid {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 2.5rem;
    max-width: 1200px;
    margin: 0 auto;
    padding: 3rem 2rem 6rem 2rem;
}

.tool-detail-main {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 3rem;
    backdrop-filter: blur(8px);
}

.tool-detail-sidebar {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.sidebar-box {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 1.75rem;
    backdrop-filter: blur(8px);
}

.sidebar-box h3 {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    padding-bottom: 0.5rem;
}

.sidebar-info-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.sidebar-info-item {
    display: flex;
    justify-content: space-between;
    font-size: 0.95rem;
}

.sidebar-info-label {
    color: var(--color-text-muted);
}

.sidebar-info-value {
    font-weight: 600;
    color: var(--color-text-main);
}

/* Trust Pages Styles (About & Contact) */
.info-section {
    max-width: 800px;
    margin: 0 auto;
    padding: 5rem 1.5rem;
}

.info-content {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 3rem;
    backdrop-filter: blur(8px);
}

.info-content h2 {
    margin-top: 2rem;
}

.info-content h2:first-of-type {
    margin-top: 0;
}

.info-content p {
    margin-bottom: 1.5rem;
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    margin-top: 2rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--color-text-main);
}

.form-group input, .form-group textarea, .form-group select {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    padding: 0.75rem 1rem;
    color: white;
    font-family: var(--font-body);
    font-size: 0.95rem;
    outline: none;
    transition: var(--transition-smooth);
}

.form-group select option {
    background-color: var(--bg-main);
    color: white;
}

.form-group input:focus, .form-group textarea:focus, .form-group select:focus {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-glow);
}

.alert {
    padding: 1rem 1.5rem;
    border-radius: var(--border-radius-sm);
    margin-bottom: 1.5rem;
    font-weight: 500;
}

.alert-success {
    background: rgba(16, 185, 129, 0.1);
    color: #10b981;
    border: 1px solid rgba(16, 185, 129, 0.2);
}

.alert-error {
    background: rgba(239, 68, 68, 0.1);
    color: #ef4444;
    border: 1px solid rgba(239, 68, 68, 0.2);
}

/* Footer */
footer {
    border-top: 1px solid var(--border-color);
    padding: 4rem 2rem 2rem 2rem;
    background-color: rgba(8, 11, 17, 0.9);
    margin-top: auto;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-brand {
    max-width: 320px;
}

.footer-brand p {
    margin-top: 1rem;
    font-size: 0.9rem;
}

.footer-links {
    display: flex;
    gap: 5rem;
}

.footer-col h4 {
    font-size: 0.95rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-main);
    margin-bottom: 1.25rem;
}

.footer-col ul {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

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

.footer-col a:hover {
    color: var(--color-text-main);
}

.footer-bottom {
    max-width: 1200px;
    margin: 0 auto;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    padding-top: 2rem;
    display: flex;
    justify-content: space-between;
    font-size: 0.85rem;
    color: var(--color-text-dark);
}

/* Mobile Responsiveness */
@media (max-width: 992px) {
    .tool-detail-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    h1 {
        font-size: 2.25rem;
    }
    
    .navbar {
        padding: 0;
    }

    .navbar-container {
        padding: 1rem 1.5rem;
    }
    
    /* Hamburger toggle styling */
    .nav-toggle {
        display: flex;
        flex-direction: column;
        justify-content: space-between;
        width: 24px;
        height: 18px;
        background: transparent;
        border: none;
        cursor: pointer;
        padding: 0;
        z-index: 110;
        outline: none;
    }
    
    .nav-toggle span {
        display: block;
        width: 100%;
        height: 2px;
        background-color: var(--color-text-main);
        border-radius: 2px;
        transition: var(--transition-smooth);
    }
    
    .nav-toggle.active span:nth-child(1) {
        transform: translateY(8px) rotate(45deg);
    }
    
    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }
    
    .nav-toggle.active span:nth-child(3) {
        transform: translateY(-8px) rotate(-45deg);
    }
    
    /* Animated drop-down mobile menu drawer */
    .nav-links {
        display: flex;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: rgba(8, 11, 17, 0.95);
        backdrop-filter: blur(16px);
        -webkit-backdrop-filter: blur(16px);
        border-bottom: 1px solid var(--border-color);
        padding: 2rem;
        flex-direction: column;
        gap: 1.5rem;
        align-items: stretch;
        z-index: 100;
        opacity: 0;
        visibility: hidden;
        transform: translateY(-12px);
        pointer-events: none;
        transition: opacity 0.3s cubic-bezier(0.4, 0, 0.2, 1), transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), visibility 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    }
    
    .nav-links.active {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
        pointer-events: auto;
    }
    
    .nav-links ul {
        flex-direction: column;
        gap: 1.5rem;
        align-items: stretch;
        width: 100%;
    }
    
    .nav-links ul li {
        width: 100%;
        text-align: center;
    }
    
    .nav-links ul li a {
        display: block;
        padding: 0.5rem 0;
    }
    
    .btn-primary {
        display: block;
        text-align: center;
        width: 100%;
    }
    
    .hero {
        padding: 3.5rem 1.5rem 2.5rem 1.5rem;
    }
    
    .search-box {
        flex-direction: column;
        background: transparent;
        border: none;
        gap: 1rem;
    }
    
    .search-box input {
        background: var(--bg-card);
        border: 1px solid var(--border-color);
        border-radius: var(--border-radius-sm);
        padding: 0.85rem 1rem;
    }
    
    .search-box button {
        width: 100%;
        padding: 0.85rem;
    }
    
    .info-content, .tool-detail-main {
        padding: 1.5rem;
    }
    
    .footer-content {
        flex-direction: column;
        gap: 2rem;
    }
    
    .footer-links {
        flex-direction: column;
        gap: 2rem;
    }
    
    .footer-bottom {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }

    /* mobile grid area swaps for single tool page reviews */
    .tool-detail-grid {
        display: grid;
        grid-template-columns: 1fr;
        grid-template-areas: 
            "sidebar-action"
            "main-content"
            "sidebar-specs";
    }

    #tool-main-content {
        grid-area: main-content;
    }

    #tool-sidebar-content {
        display: contents;
    }

    #tool-sidebar-content .sidebar-box:nth-child(1) {
        grid-area: sidebar-action;
        margin-bottom: 0.5rem;
    }

    #tool-sidebar-content .sidebar-box:nth-child(2) {
        grid-area: sidebar-specs;
        margin-top: 0.5rem;
    }
}

/* Custom Scrollbars */
::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

::-webkit-scrollbar-track {
    background: var(--bg-main);
}

::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 5px;
    border: 2px solid var(--bg-main);
    transition: var(--transition-smooth);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-primary);
}

/* Custom Selection styling */
::selection {
    background: rgba(99, 102, 241, 0.35);
    color: #ffffff;
}

/* Back to Top Floating Button styles */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: rgba(17, 24, 39, 0.85);
    border: 1px solid var(--border-color);
    color: var(--color-text-main);
    font-size: 1.1rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 99;
    opacity: 0;
    visibility: hidden;
    transform: translateY(12px);
    transition: opacity 0.3s cubic-bezier(0.4, 0, 0.2, 1), transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), visibility 0.3s cubic-bezier(0.4, 0, 0.2, 1), background-color 0.3s ease, border-color 0.3s ease;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    box-shadow: var(--shadow-md);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    background: var(--color-primary);
    border-color: var(--color-primary);
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.4);
}