/* ------------------- */
/* 1. Global & Setup  */
/* ------------------- */
:root {
    --bg-color: #121212;
    --surface-color: #1e1e1e;
    --primary-color: #00aaff;
    --primary-hover: #0088cc;
    --text-color: #e0e0e0;
    --muted-text-color: #a0a0a0;
    --border-color: #333;
    --shadow-color: rgba(0, 0, 0, 0.2);
    --header-bg: rgba(18, 18, 18, 0.8);

    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
    --spacing-unit: 1rem;
}

[data-theme="light"] {
    --bg-color: #f5f5f5;
    --surface-color: #ffffff;
    --primary-color: #0077cc;
    --primary-hover: #005599;
    --text-color: #212121;
    --muted-text-color: #616161;
    --border-color: #e0e0e0;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --header-bg: rgba(245, 245, 245, 0.8);
}

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px; /* Offset for sticky header */
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 calc(var(--spacing-unit) * 1.5);
}

h1, h2, h3 {
    line-height: 1.2;
    margin-bottom: var(--spacing-unit);
}

h1 { font-size: clamp(2.5rem, 6vw, 4rem); }
h2 { font-size: clamp(2rem, 5vw, 2.5rem); text-align: center; margin-bottom: calc(var(--spacing-unit) * 2); }
h3 { font-size: 1.25rem; }

p { margin-bottom: var(--spacing-unit); }
a { color: var(--primary-color); text-decoration: none; transition: color 0.2s; }
a:hover, a:focus-visible { color: var(--primary-hover); }

/* Accessibility: Skip Link */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--primary-color);
    color: white;
    padding: 8px;
    z-index: 100;
    transition: top 0.3s;
}
.skip-link:focus { top: 0; }

/* ----------------- */
/* 2. Header & Nav  */
/* ----------------- */
#header {
    position: sticky;
    top: 0;
    width: 100%;
    z-index: 10;
    padding: var(--spacing-unit) 0;
    transition: background-color 0.3s, box-shadow 0.3s;
}
#header.scrolled {
    background-color: var(--header-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    box-shadow: 0 2px 10px var(--shadow-color);
}
#header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.logo a { font-weight: bold; font-size: 1.5rem; color: var(--text-color); }
nav { display: flex; align-items: center; gap: calc(var(--spacing-unit) * 1.5); }
nav ul { list-style: none; display: flex; gap: var(--spacing-unit); }
nav a { font-weight: 500; padding: 0.5rem; }

/* Theme Switcher */
.theme-switcher { position: relative; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border-width: 0; }
#theme-toggle { appearance: none; width: 40px; height: 20px; background-color: var(--border-color); border-radius: 20px; position: relative; cursor: pointer; outline-offset: 4px; }
#theme-toggle::before { content: ''; position: absolute; width: 16px; height: 16px; border-radius: 50%; background-color: var(--surface-color); top: 2px; left: 2px; transition: transform 0.3s; }
#theme-toggle:checked::before { transform: translateX(20px); }

/* ------------------ */
/* 3. Page Sections  */
/* ------------------ */
section { padding: calc(var(--spacing-unit) * 4) 0; }
section:nth-of-type(odd) { background-color: var(--surface-color); }

/* Hero Section */
.hero-section {
    min-height: 80vh;
    display: flex;
    align-items: center;
    text-align: center;
}
.hero-content {
    max-width: 800px;
    margin: 0 auto;
}
.hero-content .subtitle {
    font-size: 1.5rem;
    color: var(--muted-text-color);
    margin-bottom: var(--spacing-unit);
}
.hero-content .intro {
    font-size: 1.1rem;
    max-width: 600px;
    margin: 0 auto calc(var(--spacing-unit) * 2);
}

/* About Section */
.about-container {
    display: flex; /* Changed to flex for mobile first */
    flex-direction: column; /* Stack image and text on small screens */
    gap: calc(var(--spacing-unit) * 2);
    align-items: center;
    text-align: center; /* Center text for mobile */
}
.profile-pic {
    width: 350px;    
    height: 350px;
    border-radius: 50%;
    object-fit: cover;
    border: 3px solid var(--border-color);
}
.skills-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: var(--spacing-unit);
    justify-content: center; /* Center skills on mobile */
}
.skills-list span {
    background-color: var(--border-color);
    padding: 0.3rem 0.8rem;
    border-radius: 1rem;
    font-size: 0.9rem;
    font-weight: 500;
}

/* Work Section */
.filter-buttons {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-bottom: calc(var(--spacing-unit) * 2);
    flex-wrap: wrap;
}
.filter-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--muted-text-color);
    padding: 0.5rem 1rem;
    border-radius: 2rem;
    cursor: pointer;
    transition: all 0.2s;
}
.filter-btn:hover, .filter-btn:focus-visible {
    background-color: var(--border-color);
    color: var(--text-color);
}
.filter-btn.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.work-gallery {
    display: grid;
    grid-template-columns: 1fr;
    gap: calc(var(--spacing-unit) * 1.5);
}
.card {
    background-color: var(--bg-color);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 4px 8px var(--shadow-color);
    transition: transform 0.3s, box-shadow 0.3s;
    display: flex; /* For filtering animation */
    flex-direction: column;
}
.card.hidden { display: none; } /* JS-controlled filter class */
.card:hover, .card:focus-within {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px var(--shadow-color);
}
.card img {
    width: 100%;
    height: 220px;
    object-fit: cover;
    display: block;
}
.card-content {
    padding: var(--spacing-unit);
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}
.card-content h3 { color: var(--text-color); }
.card-content p { color: var(--muted-text-color); flex-grow: 1; }
.card-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: auto; /* Pushes tags to the bottom */
    padding-top: var(--spacing-unit);
}
.card-tags span {
    background-color: var(--border-color);
    font-size: 0.8rem;
    padding: 0.2rem 0.6rem;
    border-radius: 4px;
}

/* Contact Section */
.contact-section { text-align: center; }
.contact-section p { max-width: 600px; margin: 0 auto calc(var(--spacing-unit) * 2); }
.social-links { margin-top: calc(var(--spacing-unit) * 1.5); }
.social-links a { color: var(--muted-text-color); font-weight: 500; }

/* --------------- */
/* 4. Components  */
/* --------------- */
.btn {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 0.8rem 1.8rem;
    border-radius: 2rem;
    font-weight: bold;
    text-transform: uppercase;
    letter-spacing: 1px;
    transition: background-color 0.2s, transform 0.2s;
    border: none;
    cursor: pointer;
}
.btn:hover, .btn:focus-visible {
    background-color: var(--primary-hover);
    color: white;
    transform: translateY(-2px);
}

/* ----------------- */
/* 5. Footer & BTT  */
/* ----------------- */
footer {
    text-align: center;
    padding: calc(var(--spacing-unit) * 2) 0;
    color: var(--muted-text-color);
    font-size: 0.9rem;
    border-top: 1px solid var(--border-color);
}
footer .github-link {
    font-size: 0.8rem;
    margin-top: 0.5rem;
    color: var(--muted-text-color);
}


#back-to-top {
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: opacity 0.3s, transform 0.3s;
    opacity: 0;
    transform: translateY(10px);
    pointer-events: none;
}
#back-to-top.visible {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

/* ----------------- */
/* 6. Media Queries */
/* ----------------- */
@media (min-width: 640px) {
    .work-gallery { grid-template-columns: repeat(2, 1fr); }
    
    .about-container { 
        display: grid; /* Switch back to grid for larger screens */
        grid-template-columns: 250px 1fr; /* Image takes 250px, text takes rest */
        text-align: left; /* Align text left */
        gap: calc(var(--spacing-unit) * 3);
    }
    .profile-pic { 
        width: 280px; 
        height: 280px;
        margin: 0; 
    }
    .skills-list {
        justify-content: flex-start; /* Align skills left */
    }
}

@media (min-width: 1024px) {
    .work-gallery { grid-template-columns: repeat(3, 1fr); }
    /* You could increase card count per row to 4 on larger screens if desired */
    /* .work-gallery { grid-template-columns: repeat(4, 1fr); } */
}

/* ---------------- */
/* 7. Print Styles */
/* ---------------- */
@media print {
    :root {
        --bg-color: #ffffff;
        --surface-color: #ffffff;
        --text-color: #000000;
        --muted-text-color: #333333;
    }
    header, footer, .theme-switcher, .btn, #back-to-top, .filter-buttons { display: none !important; }
    section { padding: 2rem 0; background-color: transparent !important; }
    .work-gallery { display: block; }
    .card { box-shadow: none; border: 1px solid #ccc; page-break-inside: avoid; }
}

/* Experience Section */
.experience-timeline {
    max-width: 750px;
    margin: 0 auto;
    position: relative;
}
.experience-timeline::after {
    content: '';
    position: absolute;
    width: 2px;
    background-color: var(--border-color);
    top: 0;
    bottom: 0;
    left: 20px;
    margin-left: -1px;
}
.experience-item {
    padding: 1rem 0 2rem 3rem;
    position: relative;
}
.experience-item::after {
    content: '';
    position: absolute;
    width: 12px;
    height: 12px;
    background-color: var(--bg-color);
    border: 2px solid var(--primary-color);
    top: 15px;
    left: 20px;
    border-radius: 50%;
    z-index: 1;
    margin-left: -8px;
}
.experience-item h3 {
    margin-bottom: 0.25rem;
}
.experience-info {
    font-size: 1rem;
    color: var(--muted-text-color);
    margin-bottom: 0.25rem;
}
.experience-date {
    font-size: 0.9rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-style: italic;
}