/* --- CSS Variables --- */
:root {
    /* Light Mode */
    --bg-primary: #F8FAFC;
    --bg-secondary: #FFFFFF;
    --text-primary: #0F172A;
    --text-secondary: #475569;
    --accent: #0EA5E9;
    --accent-hover: #0284C7;
    --accent-light: rgba(14, 165, 233, 0.1);
    --border-color: #E2E8F0;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 10px 25px -5px rgba(14, 165, 233, 0.25);
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
}

[data-theme="dark"] {
    /* Dark Mode */
    --bg-primary: #0F172A;
    --bg-secondary: #1E293B;
    --text-primary: #F8FAFC;
    --text-secondary: #94A3B8;
    --accent: #38BDF8;
    --accent-hover: #7DD3FC;
    --accent-light: rgba(56, 189, 248, 0.15);
    --border-color: #334155;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
    --shadow-hover: 0 10px 25px -5px rgba(56, 189, 248, 0.3);
}

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

html, body {
    overflow-x: hidden;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: background-color var(--transition-base), color var(--transition-base);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

ul {
    list-style: none;
}

/* --- Typography --- */
h1, h2, h3, h4 {
    color: var(--text-primary);
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: -0.02em;
}

.section-title {
    font-size: 2.25rem;
    margin-bottom: 3rem;
    text-align: center;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: var(--accent);
    margin: 1rem auto 0;
    border-radius: 2px;
}

p {
    color: var(--text-secondary);
}

/* --- Layout --- */
.container {
    width: 100%;
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

section {
    padding: 6rem 0;
}

/* --- Header & Nav --- */
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: rgba(var(--bg-secondary-rgb), 0.8);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    z-index: 1000;
    border-bottom: 1px solid var(--border-color);
    transition: background-color var(--transition-base), border-color var(--transition-base);
    /* For translucent effect */
    background: var(--bg-secondary);
    opacity: 0.95;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: -0.03em;
}

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

.theme-toggle, .nav-toggle {
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.25rem;
    cursor: pointer;
    transition: color var(--transition-fast);
}

.theme-toggle:hover, .nav-toggle:hover {
    color: var(--accent);
}

.nav-toggle {
    display: none;
}

nav ul {
    display: flex;
    gap: 2rem;
}

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

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

/* --- Hero Section --- */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: 70px; /* Offset for fixed header */
}

.hero-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8rem;
}

.hero-content {
    flex: 1;
}

.tagline {
    font-size: 1.125rem;
    color: var(--accent);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.hero-title {
    font-size: 4rem;
    font-weight: 800;
    letter-spacing: -0.04em;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.hero-role {
    font-size: 2rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.hero-description {
    font-size: 1.125rem;
    max-width: 500px;
    margin-bottom: 2.5rem;
}

.hero-image {
    flex: 0 0 400px;
}

.hero-image-card {
    width: 100%;
    aspect-ratio: 1 / 1;
    border-radius: 2rem;
    overflow: hidden;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

.hero-image-card img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center top;
}

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

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.875rem 1.75rem;
    border-radius: 9999px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    border: none;
    text-decoration: none;
}

.btn:not(.btn-secondary) {
    background-color: var(--accent);
    color: #FFFFFF;
    box-shadow: 0 4px 14px 0 rgba(14, 165, 233, 0.39);
}

.btn:not(.btn-secondary):hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(14, 165, 233, 0.23);
}

.btn-secondary {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: var(--border-color);
    transform: translateY(-2px);
}

/* --- About Section --- */
.about-content {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
}

.about-card {
    background-color: var(--bg-secondary);
    border-radius: 1.5rem;
    padding: 2.5rem;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.about-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
    border-color: var(--accent);
}

.about-card h3 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.about-card ul li {
    margin-bottom: 0.75rem;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-secondary);
}

.about-card ul li::before {
    content: '•';
    color: var(--accent);
    position: absolute;
    left: 0;
    font-weight: bold;
    font-size: 1.25rem;
    line-height: 1;
}

/* --- Skills Section --- */
.skills-content {
    display: grid;
    gap: 2rem;
}

#skills-content-container {
    grid-template-columns: repeat(3, 1fr);
}

#skills-content-container .skill-category:nth-child(2) {
    grid-column: span 2;
}

#specialized-tools-content-container {
    grid-template-columns: repeat(2, 1fr);
}

.skill-category {
    background-color: var(--bg-secondary);
    border-radius: 1.5rem;
    padding: 2rem;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.skill-category h3 {
    font-size: 1.125rem;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.skills-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.skill-badge {
    background-color: var(--accent-light);
    color: var(--accent);
    padding: 0.5rem 1rem;
    border-radius: 9999px;
    font-size: 0.875rem;
    font-weight: 500;
    border: 1px solid transparent;
    transition: all var(--transition-fast);
}

.skill-badge:hover {
    background-color: var(--accent);
    color: #FFFFFF;
}

/* --- Projects Section --- */
.projects-content {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.project-card {
    background-color: var(--bg-secondary);
    border-radius: 1.5rem;
    padding: 2.5rem;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
    display: flex;
    flex-direction: column;
}

.project-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-hover);
    border-color: var(--accent);
}

.project-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.tech-stack {
    font-size: 0.875rem;
    color: var(--accent);
    font-weight: 500;
    margin-bottom: 1rem;
}

.project-card p {
    margin-bottom: 2rem;
    flex: 1;
}

.link-styled {
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.link-styled:hover {
    gap: 0.75rem; /* Small arrow nudge effect */
}

/* --- Interests Section --- */
.interests-content {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
}

.interest-card {
    background-color: var(--bg-secondary);
    border-radius: 1.5rem;
    padding: 2.5rem;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
    text-align: left;
    display: flex;
    flex-direction: column;
}

.interest-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
    border-color: var(--accent);
}

.interest-icon {
    font-size: 2.5rem;
    margin-bottom: 1.5rem;
    line-height: 1;
}

.interest-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
}

.interest-card p {
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
    flex: 1;
}

/* --- Contact Section --- */
.contact-content {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
    background-color: var(--bg-secondary);
    padding: 4rem 2rem;
    border-radius: 2rem;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.contact-content p {
    font-size: 1.125rem;
    margin-bottom: 1.5rem;
}

.contact-email {
    display: inline-block;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent);
    margin-bottom: 2.5rem;
}

.social-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

.social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 3rem;
    height: 3rem;
    background-color: var(--bg-primary);
    color: var(--text-secondary);
    border-radius: 50%;
    font-size: 1.25rem;
    transition: all var(--transition-fast);
    border: 1px solid var(--border-color);
}

.social-link:hover {
    background-color: var(--accent);
    color: #FFFFFF;
    border-color: var(--accent);
    transform: translateY(-3px);
    box-shadow: 0 4px 14px 0 rgba(14, 165, 233, 0.39);
}

/* --- Footer --- */
footer {
    padding: 3rem 0;
    text-align: center;
    border-top: 1px solid var(--border-color);
}

.copyright {
    font-size: 0.875rem;
}

/* --- Back to top --- */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background-color: var(--accent);
    color: #FFFFFF;
    border-radius: 50%;
    border: none;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-fast) ease;
    box-shadow: var(--shadow-md);
    z-index: 99;
    font-size: 1.2rem;
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background-color: var(--accent-hover);
    transform: translateY(-3px);
}

/* --- Animations --- */
.fade-in {
    opacity: 0;
    animation: fadeIn 0.8s ease forwards;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Apply staggered delay for children elements where applicable */
section > .container > div > div:nth-child(1) { animation-delay: 0.1s; }
section > .container > div > div:nth-child(2) { animation-delay: 0.2s; }
section > .container > div > div:nth-child(3) { animation-delay: 0.3s; }
section > .container > div > div:nth-child(4) { animation-delay: 0.4s; }


/* --- Media Queries --- */
@media (max-width: 992px) {
    .about-content { grid-template-columns: repeat(2, 1fr); }
    #skills-content-container { grid-template-columns: repeat(2, 1fr); }
    #skills-content-container .skill-category:nth-child(2) { grid-column: span 1; }
    #specialized-tools-content-container { grid-template-columns: repeat(2, 1fr); }
    .projects-content { grid-template-columns: repeat(2, 1fr); }
    .interests-content { grid-template-columns: repeat(2, 1fr); }
    .hero-title {
        font-size: 3rem;
    }
    .hero-role {
        font-size: 1.5rem;
    }
    .hero-container {
        gap: 2rem;
    }
    .hero-image {
        flex: 0 0 320px;
    }
}

@media (max-width: 768px) {
    .nav-toggle {
        display: block;
        /* Position explicitly if needed, but flex container should handle it */
    }

    nav {
        position: fixed;
        top: 70px;
        left: 0;
        width: 100%;
        background-color: var(--bg-secondary);
        border-bottom: 1px solid var(--border-color);
        padding: 2rem 0;
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
        z-index: 999;
    }

    nav.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    nav ul {
        flex-direction: column;
        align-items: center;
        gap: 1.5rem;
    }

    .nav-controls {
        z-index: 1001; /* Ensure button stays on top */
    }

    .hero {
        padding-top: 100px;
    }

    .hero-container {
        flex-direction: column;
        text-align: center;
        gap: 3rem;
    }

    .hero-image {
        flex: 0 0 auto;
        width: 250px;
    }

    .hero-description {
        margin: 0 auto 2.5rem;
    }

    .hero-buttons {
        justify-content: center;
    }

    .about-content, #skills-content-container, #specialized-tools-content-container, .projects-content {
        grid-template-columns: 1fr;
    }

    .interests-content {
        grid-template-columns: repeat(2, 1fr);
    }

    section {
        padding: 4rem 0;
    }
}

@media (max-width: 480px) {
    .section-title {
        font-size: 1.75rem;
    }
    .hero-title {
        font-size: 2.5rem;
    }
    .hero-role {
        font-size: 1.25rem;
    }
    .interests-content {
        grid-template-columns: 1fr;
    }
    .hero-buttons {
        flex-direction: column;
        width: 100%;
        max-width: 300px;
        margin: 0 auto;
    }
    .btn {
        width: 100%;
    }
    .contact-email {
        font-size: 1.25rem;
    }
}