/* Custom Properties for Final Recommended Palette */
:root {
    --color-primary: #0BB4D4; /* Primary (Light Blue) */
    --color-primary-dark: #0F6EA6; /* Primary Dark */
    --color-accent: #8b5cf6; /* Dark Accent (Purple) - Used for highlights/icons */
    --color-text-dark: #1A1A1A; /* Heading/Text Dark */
    --color-text-secondary: #4F4F4F; /* Secondary Text */
    --color-background-light: #F7F9FC; /* Background Light */
    --color-card-background: #FFFFFF; /* Card Background */
    --color-card-border: #E5E5E5; /* Card Border */
    
    /* Custom Colors for Light Code Block */
    --color-code-background: #F3F5F7;
    --color-code-text: #1A1A1A;
    --color-code-border: #DADADA;

    --color-shadow: rgba(0, 0, 0, 0.08);
    --font-family-primary: 'Inter', sans-serif;
    --border-radius: 8px;
    --transition-speed: 0.3s;
}

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

body {
    font-family: var(--font-family-primary);
    line-height: 1.6;
    color: var(--color-text-dark);
    background-color: var(--color-background-light);
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Typography */
h1, h2, h3 {
    font-weight: 600; /* Inter Semibold */
    color: var(--color-text-dark);
}

h2 {
    font-size: 2.2rem;
    color: var(--color-primary-dark);
    margin-bottom: 30px;
}

/* Specific Font Weights */
body { font-weight: 400; } /* Inter Regular */
strong { font-weight: 600; } /* Bolding for Headings/Key text */
h4 { font-weight: 500; } /* Inter Medium (used for metric numbers/titles) */


.section-title {
    text-align: center;
    padding-bottom: 10px;
    border-bottom: 3px solid var(--color-card-border);
    margin-bottom: 40px;
}

.section-intro {
    text-align: center;
    color: var(--color-text-secondary);
    font-style: italic;
    margin-bottom: 40px;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 25px;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 600; /* Inter Semibold */
    transition: all var(--transition-speed) ease-in-out;
    border: none;
    cursor: pointer;
}

.btn-primary {
    background: var(--color-primary-dark);
    color: var(--color-card-background);
    box-shadow: 0 4px 15px rgba(15, 110, 166, 0.4);
}

.btn-primary:hover {
    background: #0d5f8f;
    box-shadow: 0 6px 20px rgba(15, 110, 166, 0.6);
    transform: translateY(-2px);
}

.btn-secondary {
    background-color: var(--color-primary);
    color: var(--color-text-dark);
    box-shadow: 0 4px 10px rgba(11, 180, 212, 0.3);
}

.btn-secondary:hover {
    background-color: #0994b2;
    transform: translateY(-2px);
}

/* Hero Section: Updated Gradient Background with Image Blend */
.hero {
    /* Use the abstract blue image provided (rename it to hero_bg.jpg) */
    background: url('hero_bg.jpg') center center/cover no-repeat;
    /* Added color overlay using the dark accent color to deepen the blue */
    background-color: var(--color-primary-dark); 
    background-blend-mode: overlay; 
    color: var(--color-card-background);
    text-align: center;
    padding: 150px 20px 100px;
    min-height: 80vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.hero-title {
    font-size: 3.5rem;
    margin-bottom: 15px;
    color: var(--color-card-background);
}

.hero-subtitle {
    font-size: 1.5rem;
    font-weight: 400;
    margin-bottom: 40px;
    opacity: 0.9;
    color: var(--color-card-background);
}

/* Authors Section */
.authors-section {
    padding: 60px 20px;
    background-color: var(--color-card-background);
}

.author-cards {
    display: flex;
    justify-content: center;
    gap: 40px;
    margin-top: 40px;
}

.author-card {
    text-align: center;
    padding: 20px;
    border-radius: var(--border-radius);
    background-color: var(--color-card-background);
    box-shadow: 0 4px 10px var(--color-shadow);
    transition: transform var(--transition-speed) ease-in-out;
    width: 250px;
}

.author-card:hover {
    transform: translateY(-5px);
}

/* Photo Placeholder: Decent Bubble Style */
.photo-placeholder {
    width: 100px;
    height: 100px;
    background: var(--color-card-background); 
    border-radius: 50%;
    margin: 0 auto 15px;
    border: 3px solid transparent; 
    background-clip: padding-box;
    /* Clean blue border */
    box-shadow: 0 0 0 3px var(--color-primary), inset 0 0 0 1000px var(--color-background-light); 
    transition: box-shadow var(--transition-speed);
}

.author-card:hover .photo-placeholder {
     /* Darker blue border on hover */
    box-shadow: 0 0 0 3px var(--color-primary-dark), inset 0 0 0 1000px var(--color-background-light);
}

.authors-affiliate {
    text-align: center;
    margin-top: 20px;
    font-style: italic;
    color: var(--color-text-secondary);
}

/* Report Sections */
.report-section {
    padding: 80px 20px;
    border-bottom: 1px solid var(--color-card-border);
}

.bg-light-gray {
    background-color: var(--color-background-light);
}

/* Icons */
.icon-purple {
    color: var(--color-primary); /* Using Primary Blue for main icons */
    margin-right: 10px;
}
.icon-blue {
    color: var(--color-primary-dark);
    margin-right: 10px;
}

/* Problem Identification Grid */
.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.info-card {
    background-color: var(--color-card-background);
    padding: 25px;
    border-radius: var(--border-radius);
    box-shadow: 0 6px 20px var(--color-shadow);
    transition: transform var(--transition-speed);
    color: var(--color-text-secondary);
}

.info-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.info-card i {
    font-size: 2rem;
    margin-bottom: 15px;
}

.info-card h3 {
    margin-bottom: 10px;
    font-size: 1.2rem;
    color: var(--color-text-dark);
}

/* Data Sourcing */
.data-sourcing-content {
    display: flex;
    gap: 40px;
    align-items: stretch;
}

.data-metadata-card, .data-description-box {
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: 0 4px 15px var(--color-shadow);
    flex: 1;
}

.data-metadata-card {
    background-color: var(--color-card-background);
}

.data-description-box {
    background-color: var(--color-background-light);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.metadata-item {
    margin-bottom: 15px;
    font-size: 1rem;
    color: var(--color-text-secondary);
}

.metadata-item i {
    color: var(--color-primary);
    margin-right: 10px;
}

/* Pipeline Design */
.pipeline-steps-grid {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
    justify-content: center;
}

.pipeline-step-card {
    background-color: var(--color-card-background);
    padding: 25px;
    border-radius: var(--border-radius);
    box-shadow: 0 4px 10px var(--color-shadow);
    text-align: center;
    flex: 1;
    min-width: 180px;
    max-width: 250px;
    border-top: 5px solid var(--color-primary);
    color: var(--color-text-secondary);
}

.step-icon i {
    font-size: 3rem;
    color: var(--color-primary-dark);
    margin-bottom: 10px;
}

.arch-diagram-placeholder {
    margin-top: 60px;
    text-align: center;
    padding: 30px;
    background-color: var(--color-card-background);
    border-radius: var(--border-radius);
    box-shadow: 0 4px 15px var(--color-shadow);
}

.diagram-note {
    font-style: italic;
    color: var(--color-text-secondary);
    margin-bottom: 20px;
}

/* ML Methodology */
.ml-subsections {
    display: flex;
    gap: 40px;
}

.ml-col {
    flex: 1;
    min-width: 40%;
}

.ml-col h3 {
    border-bottom: 2px solid var(--color-primary);
    padding-bottom: 5px;
    margin-bottom: 20px;
    color: var(--color-text-dark);
}

.ml-col ul {
    list-style: none;
}

.ml-col ul li {
    margin-bottom: 15px;
    padding-left: 20px;
    color: var(--color-text-secondary);
}

.ml-col ul li i {
    color: var(--color-primary);
    margin-left: -20px;
    margin-right: 5px;
}

.justification-box {
    background-color: var(--color-background-light); 
    border-left: 5px solid var(--color-primary);
    padding: 20px;
    border-radius: var(--border-radius);
    box-shadow: 0 2px 5px var(--color-shadow);
}

.algorithm-name {
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--color-text-dark);
}

.dataset-analysis {
    margin-top: 50px;
}

.analysis-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.analysis-card {
    text-align: center;
    padding: 20px;
    background-color: var(--color-background-light);
    border-radius: var(--border-radius);
    border: 1px solid var(--color-card-border);
    color: var(--color-text-secondary);
}

.analysis-card i {
    font-size: 2rem;
    color: var(--color-primary-dark);
    margin-bottom: 10px;
}

/* Implementation Plan */
.library-list {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin-bottom: 40px;
}

.library-list li {
    background-color: var(--color-card-background);
    padding: 10px 15px;
    border-radius: var(--border-radius);
    box-shadow: 0 2px 5px var(--color-shadow);
    font-weight: 500; /* Inter Medium */
}
.library-list li i {
    color: var(--color-primary-dark);
    margin-right: 5px;
}

/* Change code block background to specified light colors */
.code-block {
    background-color: var(--color-code-background); 
    color: var(--color-code-text); 
    padding: 20px;
    border-radius: 10px; /* Matching the 10px specification */
    border: 1px solid var(--color-code-border); /* Adding the border */
    overflow-x: auto;
    font-family: 'JetBrains Mono', monospace; /* Using a clean coding font (JetBrains Mono is preferred) */
    font-size: 15px;
    white-space: pre-wrap;
    line-height: 1.4;
    box-shadow: 0 4px 15px var(--color-shadow); /* Keeping a light shadow */
}

/* Evaluation Metrics */
.metric-cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 30px;
}

.metric-card {
    background-color: var(--color-card-background);
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: 0 8px 30px var(--color-shadow);
    border-left: 5px solid var(--color-primary-dark);
    color: var(--color-text-secondary);
}

.metric-card i {
    font-size: 2.5rem;
    margin-bottom: 15px;
    color: var(--color-primary);
}

.metric-card h4 {
    font-weight: 500; /* Inter Medium */
    color: var(--color-primary-dark);
    margin-bottom: 10px;
}

/* Conclusion */
.highlight-box {
    background: var(--color-primary-dark);
    color: var(--color-card-background);
    padding: 25px;
    border-radius: var(--border-radius);
    text-align: center;
    font-size: 1.4rem;
    font-weight: 600;
    box-shadow: 0 10px 25px rgba(15, 110, 166, 0.4);
}

/* Footer: Changed from black to dark gray text/background */
footer {
    background-color: var(--color-background-light); /* Matching the light background of the section above */
    color: var(--color-text-secondary); /* Dark text for readability */
    padding: 40px 20px;
    text-align: center;
    font-size: 0.9rem;
    border-top: 1px solid var(--color-card-border);
}

footer .container {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.footer-info, .footer-authors {
    margin-bottom: 10px;
}

.copyright {
    margin-top: 20px;
    opacity: 0.7;
}

/* Animations */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.fade-in.active {
    opacity: 1;
    transform: translateY(0);
}

.delay-2 { transition-delay: 0.2s; }
.delay-4 { transition-delay: 0.4s; }


/* Responsive Design */
@media (max-width: 900px) {
    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.2rem;
    }

    .author-cards, .ml-subsections, .data-sourcing-content {
        flex-direction: column;
    }
    
    .ml-col {
        min-width: 100%;
    }

    .pipeline-steps-grid {
        justify-content: space-around;
    }
    .pipeline-step-card {
        max-width: 45%;
    }
}
@media (max-width: 600px) {
    .hero {
        padding: 100px 20px 70px;
    }
    h2 {
        font-size: 1.8rem;
    }
    .pipeline-step-card {
        max-width: 100%;
    }

} 
/* Custom Properties for Final Recommended Palette */
:root {
    --color-primary: #0BB4D4; /* Primary (Light Blue) */
    --color-primary-dark: #0F6EA6; /* Primary Dark */
    --color-accent: #8b5cf6; /* Dark Accent (Purple) - Used for highlights/icons */
    --color-text-dark: #1A1A1A; /* Heading/Text Dark */
    --color-text-secondary: #4F4F4F; /* Secondary Text */
    --color-background-light: #F7F9FC; /* Background Light */
    --color-card-background: #FFFFFF; /* Card Background */
    --color-card-border: #E5E5E5; /* Card Border */
    
    /* Custom Colors for Light Code Block */
    --color-code-background: #F3F5F7;
    --color-code-text: #1A1A1A;
    --color-code-border: #DADADA;

    --color-shadow: rgba(0, 0, 0, 0.08);
    --font-family-primary: 'Inter', sans-serif;
    --border-radius: 8px;
    --transition-speed: 0.3s;
}

/* Base Styles */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    scroll-behavior: smooth; /* Smooth scrolling for nav links */
}

body {
    font-family: var(--font-family-primary);
    line-height: 1.6;
    color: var(--color-text-dark);
    background-color: var(--color-background-light);
    overflow-x: hidden;
    padding-top: 60px; /* Space for fixed navigation bar */
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Typography */
h1, h2, h3 {
    font-weight: 600; /* Inter Semibold */
    color: var(--color-text-dark);
}

h2 {
    font-size: 2.2rem;
    color: var(--color-primary-dark);
    margin-bottom: 30px;
}

/* Specific Font Weights */
body { font-weight: 400; } 
strong { font-weight: 600; } 
h4 { font-weight: 500; } 


.section-title {
    text-align: center;
    padding-bottom: 10px;
    border-bottom: 3px solid var(--color-card-border);
    margin-bottom: 40px;
}

.section-intro {
    text-align: center;
    color: var(--color-text-secondary);
    font-style: italic;
    margin-bottom: 40px;
}

/* --- Navigation Bar --- */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: var(--color-card-background);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    z-index: 1000;
    height: 60px;
    display: flex;
    align-items: center;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.navbar-brand {
    font-weight: 700;
    color: var(--color-primary-dark);
    font-size: 1.2rem;
}

.nav-links a {
    color: var(--color-text-secondary);
    text-decoration: none;
    font-weight: 500;
    margin-left: 25px;
    padding-bottom: 3px;
    transition: all 0.3s;
    border-bottom: 2px solid transparent; /* Ensure space for border */
}

.nav-links a:hover {
    color: var(--color-primary);
    border-bottom: 2px solid var(--color-primary);
}

.nav-links a.active { /* Scroll Spy Active Style */
    color: var(--color-primary);
    border-bottom: 2px solid var(--color-primary);
}


/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 25px;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 600; 
    transition: all var(--transition-speed) ease-in-out;
    border: none;
    cursor: pointer;
}

.btn-primary {
    background: var(--color-primary-dark);
    color: var(--color-card-background);
    box-shadow: 0 4px 15px rgba(15, 110, 166, 0.4);
}

.btn-primary:hover {
    background: #0d5f8f;
    box-shadow: 0 6px 20px rgba(15, 110, 166, 0.6);
    transform: translateY(-2px);
}

.btn-secondary {
    background-color: var(--color-primary);
    color: var(--color-text-dark);
    box-shadow: 0 4px 10px rgba(11, 180, 212, 0.3);
}

.btn-secondary:hover {
    background-color: #0994b2;
    transform: translateY(-2px);
}

/* Hero Section */
.hero {
    background: url('hero_bg.jpg') center center/cover no-repeat;
    background-color: var(--color-primary-dark); 
    background-blend-mode: overlay; 
    color: var(--color-card-background);
    text-align: center;
    padding: 150px 20px 100px;
    min-height: 80vh;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
}

.hero-title {
    font-size: 3.5rem;
    margin-bottom: 15px;
    color: var(--color-card-background);
}

.hero-subtitle {
    font-size: 1.5rem;
    font-weight: 400;
    margin-bottom: 40px;
    opacity: 0.9;
    color: var(--color-card-background);
}

/* Authors Section */
.authors-section {
    padding: 60px 20px;
    background-color: var(--color-card-background);
}

.author-cards {
    display: flex;
    justify-content: center;
    gap: 40px;
    margin-top: 40px;
}

.author-card {
    text-align: center;
    padding: 20px;
    border-radius: var(--border-radius);
    background-color: var(--color-card-background);
    box-shadow: 0 4px 10px var(--color-shadow);
    transition: all var(--transition-speed) ease-in-out; 
    width: 250px;
}
/* Shadow Hover Effect */
.author-card:hover, .info-card:hover, .pipeline-step-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15); /* Lift card and deepen shadow */
}

/* Photo Placeholder: Decent Bubble Style */
.photo-placeholder {
    width: 100px;
    height: 100px;
    background: var(--color-card-background); 
    border-radius: 50%;
    margin: 0 auto 15px;
    border: 3px solid transparent; 
    background-clip: padding-box;
    box-shadow: 0 0 0 3px var(--color-primary), inset 0 0 0 1000px var(--color-background-light); 
    transition: box-shadow var(--transition-speed);
}

.author-card:hover .photo-placeholder {
    box-shadow: 0 0 0 3px var(--color-primary-dark), inset 0 0 0 1000px var(--color-background-light);
}

.authors-affiliate {
    text-align: center;
    margin-top: 20px;
    font-style: italic;
    color: var(--color-text-secondary);
}

/* Report Sections */
.report-section {
    padding: 80px 20px;
    border-bottom: 1px solid var(--color-card-border);
}

.bg-light-gray {
    background-color: var(--color-background-light);
}

/* Icons */
.icon-purple {
    color: var(--color-primary); 
    margin-right: 10px;
}
.icon-blue {
    color: var(--color-primary-dark);
    margin-right: 10px;
}

/* Problem Identification Grid */
.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.info-card {
    background-color: var(--color-card-background);
    padding: 25px;
    border-radius: var(--border-radius);
    box-shadow: 0 6px 20px var(--color-shadow);
    transition: transform var(--transition-speed);
    color: var(--color-text-secondary);
}

/* Data Sourcing */
.data-sourcing-content {
    display: flex;
    gap: 40px;
    align-items: stretch;
}

.data-metadata-card, .data-description-box {
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: 0 4px 15px var(--color-shadow);
    flex: 1;
}

/* Pipeline Design Grid */
.pipeline-steps-grid {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
    justify-content: center;
    margin-bottom: 50px; 
}

.pipeline-step-card {
    background-color: var(--color-card-background);
    padding: 25px;
    border-radius: var(--border-radius);
    box-shadow: 0 4px 10px var(--color-shadow);
    text-align: center;
    flex: 1;
    min-width: 180px;
    max-width: 250px;
    border-top: 5px solid var(--color-primary);
    color: var(--color-text-secondary);
    transition: all var(--transition-speed) ease-in-out; 
}

.step-icon i {
    font-size: 3rem;
    color: var(--color-primary-dark);
    margin-bottom: 10px;
}

/* Architecture Integration Section */
.arch-integration {
    text-align: center;
    padding: 40px 20px;
    background-color: var(--color-card-background);
    border-radius: var(--border-radius);
    box-shadow: 0 4px 15px var(--color-shadow);
}

.arch-heading {
    color: var(--color-primary-dark);
    margin-bottom: 10px;
    font-size: 1.8rem;
}

.arch-subheading {
    color: var(--color-text-secondary);
    margin-bottom: 30px;
}

.diagram-image {
    max-width: 90%;
    height: auto;
    border-radius: 8px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.15);
    border: 1px solid var(--color-card-border);
}

/* ML Methodology - SPACING FIXES */
.ml-subsections {
    display: flex;
    gap: 40px;
    margin-top: 20px; 
}
.ml-subsections .ml-col h3 {
    margin-top: 30px; /* Ensure spacing above subheadings */
    margin-bottom: 20px;
}

.ml-col {
    flex: 1;
    min-width: 40%;
    position: relative; 
}

/* Sticky Justification Box Styles */
.justification-box {
    background-color: var(--color-background-light); 
    border-left: 5px solid var(--color-primary);
    padding: 20px;
    border-radius: var(--border-radius);
    box-shadow: 0 2px 5px var(--color-shadow);
    z-index: 900; 
}

/* --- Block Containers (Dataset Analysis, Library Selection) --- */
.info-block-card {
    /* Base style for bubble containers */
    background-color: var(--color-card-background);
    border-radius: var(--border-radius);
    box-shadow: 0 4px 15px var(--color-shadow);
    padding: 25px;
    margin-top: 30px;
    margin-bottom: 30px;
    border: 1px solid var(--color-card-border); 
}

/* Apply block to Dataset Analysis structure */
.dataset-analysis h3 {
    margin-top: 30px; 
}

.dataset-analysis .analysis-cards {
    background-color: var(--color-card-background);
    border-radius: var(--border-radius);
    box-shadow: 0 4px 15px var(--color-shadow);
    padding: 25px;
    margin-top: 20px; /* Separate block from heading */
}

/* Apply block to Library Selection structure */
.implementation-plan-content {
    background-color: var(--color-card-background);
    border-radius: var(--border-radius);
    box-shadow: 0 4px 15px var(--color-shadow);
    padding: 25px;
    margin-top: 20px;
}


/* Implementation Plan */
.library-list {
    margin-top: 20px;
}
.library-list li {
    font-weight: 500; 
}

/* Code Block Styling */
.code-block {
    background-color: var(--color-code-background); 
    color: var(--color-code-text); 
    padding: 20px;
    border-radius: 10px; 
    border: 1px solid var(--color-code-border); 
    overflow-x: auto;
    font-family: 'JetBrains Mono', monospace; 
    font-size: 15px;
    white-space: pre-wrap;
    line-height: 1.4;
    box-shadow: 0 4px 15px var(--color-shadow); 
    margin-top: 20px; /* Space above code block */
}

/* Evaluation Metrics */
.metric-cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 30px;
}

.metric-card {
    background-color: var(--color-card-background);
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: 0 8px 30px var(--color-shadow);
    border-left: 5px solid var(--color-primary-dark);
    color: var(--color-text-secondary);
}

/* Conclusion */
.highlight-box {
    background: var(--color-primary-dark);
    color: var(--color-card-background);
    padding: 25px;
    border-radius: var(--border-radius);
    text-align: center;
    font-size: 1.4rem;
    font-weight: 600;
    box-shadow: 0 10px 25px rgba(15, 110, 166, 0.4);
}

/* Footer: Light background and text */
footer {
    background-color: var(--color-background-light); 
    color: var(--color-text-secondary); 
    padding: 40px 20px;
    text-align: center;
    font-size: 0.9rem;
    border-top: 1px solid var(--color-card-border);
}

footer .container {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.copyright {
    margin-top: 20px;
    opacity: 0.7;
}

/* Floating Action Button (Back to Top) Styles */
.back-to-top-btn {
    display: none; 
    position: fixed;
    bottom: 30px;
    right: 30px;
    z-index: 990;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: var(--color-primary-dark);
    color: var(--color-card-background);
    border: none;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
    transition: all 0.3s ease;
    font-size: 1.2rem;
}

.back-to-top-btn:hover {
    background-color: var(--color-primary);
    box-shadow: 0 6px 15px rgba(0, 0, 0, 0.35);
}

/* Animations */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.fade-in.active {
    opacity: 1;
    transform: translateY(0);
}

.delay-2 { transition-delay: 0.2s; }
.delay-4 { transition-delay: 0.4s; }


/* Responsive Design */
@media (max-width: 900px) {
    .navbar .container {
        flex-direction: column;
        padding-top: 10px;
        padding-bottom: 10px;
        height: auto;
    }
    body {
        padding-top: 85px; /* Adjust padding for expanded mobile nav */
    }
    .nav-links a {
        margin: 0 10px;
    }
    .ml-subsections {
        flex-direction: column;
    }
    /* Sticky becomes static on mobile to save space */
    .justification-box {
        position: static !important; 
        width: auto !important;
        margin-top: 30px;
    }
}
@media (max-width: 600px) {
    .hero {
        padding: 100px 20px 70px;
    }
    h2 {
        font-size: 1.8rem;
    }
    .pipeline-step-card {
        max-width: 100%;
    }
}