/* ==========================================================================
   style.css — Portfolio Website Styles
   ========================================================================== */

/* CSS Variables & Theme Setup */
:root {
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

    /* Light theme (default) */
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-card: #ffffff;
    --bg-hover: #f1f5f9;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --accent: #4f46e5;
    --accent-light: #eef2ff;
    --accent-hover: #4338ca;
    --border: #e2e8f0;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 10px 25px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --transition: 0.25s ease;
    --navbar-height: 60px;
}

/* Dark theme */
[data-theme="dark"] {
    --bg-primary: #0b1120;
    --bg-secondary: #111827;
    --bg-card: #1e293b;
    --bg-hover: #273449;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-muted: #64748b;
    --accent: #818cf8;
    --accent-light: #1e1b4b;
    --accent-hover: #6366f1;
    --border: #2d3b4f;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -2px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 25px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: calc(var(--navbar-height) + 20px);
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.65;
    transition: background-color var(--transition), color var(--transition);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    min-height: 100vh;
}

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

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

code {
    font-family: var(--font-mono);
    background: var(--bg-hover);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.85em;
}

/* Loading & Error Screens */
.loading-screen,
.error-screen {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    gap: 16px;
    font-family: var(--font-sans);
    color: var(--text-secondary);
    background: var(--bg-primary);
}

.loader {
    width: 48px;
    height: 48px;
    border: 4px solid var(--border);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.error-content {
    text-align: center;
    max-width: 400px;
    padding: 24px;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border);
}

.error-content h2 {
    margin-bottom: 8px;
    color: #dc2626;
}

.error-content button {
    margin-top: 16px;
    padding: 10px 24px;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-family: var(--font-sans);
    font-size: 0.95rem;
    font-weight: 600;
    transition: background var(--transition);
}

.error-content button:hover {
    background: var(--accent-hover);
}

/* ==========================================================================
   Navbar
   ========================================================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--navbar-height);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    z-index: 1000;
    transition: background var(--transition), border-color var(--transition),
        box-shadow var(--transition);
}

.navbar.scrolled {
    box-shadow: var(--shadow-md);
}

.nav-container {
    width: 100%;
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}

.nav-brand {
    font-weight: 800;
    font-size: 1.1rem;
    letter-spacing: -0.02em;
    color: var(--text-primary);
    white-space: nowrap;
}

.nav-links {
    display: flex;
    gap: 4px;
    flex-wrap: wrap;
    justify-content: center;
}

.nav-links a {
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 500;
    padding: 6px 12px;
    border-radius: var(--radius-sm);
    transition: color var(--transition), background var(--transition);
    text-decoration: none;
}

.nav-links a:hover {
    color: var(--accent);
    background: var(--accent-light);
    text-decoration: none;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 8px 10px;
    cursor: pointer;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color var(--transition), border-color var(--transition),
        background var(--transition);
}

.theme-toggle:hover {
    color: var(--accent);
    border-color: var(--accent);
    background: var(--accent-light);
}

.mobile-nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 6px;
}

.mobile-nav-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: transform var(--transition), opacity var(--transition);
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    padding: calc(var(--navbar-height) + 48px) 24px 40px;
    text-align: center;
    transition: background var(--transition), border-color var(--transition);
}

.hero-content {
    max-width: 700px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 2.8rem;
    font-weight: 900;
    letter-spacing: -0.03em;
    color: var(--text-primary);
    margin-bottom: 8px;
    line-height: 1.15;
}

.hero-contact {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
    gap: 8px 16px;
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-top: 8px;
}

.hero-contact a {
    color: var(--accent);
    font-weight: 500;
    text-decoration: none;
    transition: color var(--transition);
}

.hero-contact a:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

.hero-contact .dot-separator {
    color: var(--text-muted);
    font-size: 0.7rem;
}

/* ==========================================================================
   Main Container & Sections
   ========================================================================== */
.main-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 32px 24px 64px;
    display: flex;
    flex-direction: column;
    gap: 40px;
}

.section {
    scroll-margin-top: calc(var(--navbar-height) + 20px);
}

.section-title {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    color: var(--text-primary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-size: 1.1rem;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--accent);
    margin-bottom: 20px;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 60px;
    height: 2px;
    background: var(--accent);
}

.section-content {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

/* ==========================================================================
   Education Cards
   ========================================================================== */
.education-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 16px;
}

.education-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 20px;
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition), border-color var(--transition),
        transform var(--transition);
}

.education-card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--accent);
    transform: translateY(-2px);
}

.education-card .degree {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--text-primary);
}

.education-card .institute {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin: 4px 0;
}

.education-card .details {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 8px;
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 500;
}

.education-card .details .score {
    background: var(--accent-light);
    color: var(--accent);
    padding: 2px 10px;
    border-radius: 20px;
    font-weight: 600;
    font-size: 0.8rem;
}

/* ==========================================================================
   Skills
   ========================================================================== */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 16px;
}

.skill-category {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 18px;
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition), border-color var(--transition);
}

.skill-category:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--accent);
}

.skill-category .category-name {
    font-weight: 700;
    font-size: 0.9rem;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.04em;
    margin-bottom: 10px;
}

.skill-category .skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.skill-tag {
    background: var(--bg-hover);
    color: var(--text-secondary);
    font-size: 0.82rem;
    font-weight: 500;
    padding: 4px 12px;
    border-radius: 20px;
    transition: background var(--transition), color var(--transition);
}

.skill-tag:hover {
    background: var(--accent-light);
    color: var(--accent);
}

/* ==========================================================================
   Experience & Projects (Cards with bullets)
   ========================================================================== */
.experience-card,
.project-card,
.research-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition), border-color var(--transition),
        transform var(--transition);
}

.experience-card:hover,
.project-card:hover,
.research-card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--accent);
    transform: translateY(-2px);
}

.card-header {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: flex-start;
    gap: 8px 16px;
    margin-bottom: 12px;
}

.card-header .left .company-name,
.card-header .left .project-name,
.card-header .left .research-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
}

.card-header .left .role,
.card-header .left .tech-tag {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-style: italic;
    font-weight: 500;
}

.card-header .right {
    text-align: right;
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 500;
    white-space: nowrap;
}

.card-header .right .location {
    display: block;
    font-size: 0.8rem;
}

.card-header .right .duration {
    display: block;
    font-weight: 600;
    color: var(--accent);
}

.bullet-list {
    list-style: none;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.bullet-list li {
    position: relative;
    padding-left: 20px;
    font-size: 0.92rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.bullet-list li::before {
    content: '▸';
    position: absolute;
    left: 0;
    top: 0;
    color: var(--accent);
    font-weight: 700;
    font-size: 0.9rem;
}

.bullet-list li strong {
    color: var(--text-primary);
    font-weight: 600;
}

/* ==========================================================================
   Achievements
   ========================================================================== */
.achievements-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 12px;
}

.achievement-item {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 16px 20px;
    display: flex;
    align-items: center;
    gap: 12px;
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition), border-color var(--transition),
        transform var(--transition);
    font-size: 0.92rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.achievement-item:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--accent);
    transform: translateY(-2px);
}

.achievement-item .icon {
    flex-shrink: 0;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: var(--accent-light);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--accent);
    font-size: 1rem;
    font-weight: 700;
}

.achievement-item strong {
    color: var(--text-primary);
    font-weight: 600;
}

/* ==========================================================================
   Coursework
   ========================================================================== */
.coursework-container {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 20px;
    box-shadow: var(--shadow-sm);
}

.coursework-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.coursework-tag {
    background: var(--accent-light);
    color: var(--accent);
    font-size: 0.88rem;
    font-weight: 600;
    padding: 6px 16px;
    border-radius: 20px;
    transition: background var(--transition), color var(--transition);
}

.coursework-tag:hover {
    background: var(--accent);
    color: #fff;
}

/* ==========================================================================
   Footer
   ========================================================================== */
.footer {
    text-align: center;
    padding: 32px 24px;
    border-top: 1px solid var(--border);
    font-size: 0.85rem;
    color: var(--text-muted);
    background: var(--bg-secondary);
    transition: background var(--transition), border-color var(--transition);
}

/* ==========================================================================
   Responsive Design
   ========================================================================== */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: var(--navbar-height);
        left: 0;
        right: 0;
        background: var(--bg-secondary);
        border-bottom: 1px solid var(--border);
        flex-direction: column;
        align-items: center;
        padding: 12px 0;
        gap: 2px;
        box-shadow: var(--shadow-md);
    }

    .nav-links.open {
        display: flex;
    }

    .nav-links a {
        width: 100%;
        text-align: center;
        padding: 10px 16px;
        font-size: 0.95rem;
    }

    .mobile-nav-toggle {
        display: flex;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .hero {
        padding: calc(var(--navbar-height) + 32px) 16px 28px;
    }

    .main-container {
        padding: 24px 16px 48px;
        gap: 28px;
    }

    .section-title {
        font-size: 1rem;
    }

    .card-header {
        flex-direction: column;
        gap: 4px;
    }

    .card-header .right {
        text-align: left;
        font-size: 0.8rem;
    }

    .education-grid,
    .skills-grid,
    .achievements-list {
        grid-template-columns: 1fr;
    }

    .experience-card,
    .project-card,
    .research-card {
        padding: 18px;
    }
}

@media (max-width: 400px) {
    .hero h1 {
        font-size: 1.6rem;
    }

    .hero-contact {
        font-size: 0.82rem;
        gap: 4px 8px;
    }

    .bullet-list li {
        font-size: 0.85rem;
        padding-left: 16px;
    }

    .experience-card,
    .project-card,
    .research-card {
        padding: 14px;
    }
}

/* Print styles — so the portfolio can be printed as a resume */
@media print {
    .navbar,
    .theme-toggle,
    .mobile-nav-toggle,
    .footer {
        display: none !important;
    }

    .hero {
        padding: 20px 0;
        border-bottom: 2px solid #000;
    }

    .hero h1 {
        font-size: 2.2rem;
        color: #000;
    }

    .hero-contact,
    .hero-contact a {
        color: #333;
    }

    .main-container {
        padding: 20px 0;
        gap: 20px;
    }

    body {
        background: #fff;
        color: #000;
        font-size: 11px;
    }

    .section-title {
        color: #000;
        border-bottom-color: #333;
    }

    .experience-card,
    .project-card,
    .research-card,
    .education-card,
    .skill-category,
    .achievement-item,
    .coursework-container {
        box-shadow: none;
        border: 1px solid #ccc;
        break-inside: avoid;
    }

    .bullet-list li {
        color: #333;
    }

    .bullet-list li strong {
        color: #000;
    }
}