/* ===== CSS Variables / Theming ===== */
:root {
    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 2rem;
    --space-xl: 4rem;
    --space-2xl: 6rem;

    /* Transitions */
    --transition: 0.3s ease;
    --transition-slow: 0.6s ease;

    /* Border radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
}

/* Dark theme (default) */
[data-theme="dark"] {
    --bg-primary: #0f0f0f;
    --bg-secondary: #161616;
    --bg-card: #1a1a1a;
    --bg-card-hover: #222;
    --bg-nav: rgba(15, 15, 15, 0.85);
    --text-primary: #f0f0f0;
    --text-secondary: #a0a0a0;
    --text-muted: #666;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --accent-glow: rgba(59, 130, 246, 0.15);
    --border: #2a2a2a;
    --tag-bg: #1e293b;
    --tag-text: #93c5fd;
    --timeline-line: #2a2a2a;
    --timeline-dot: #3b82f6;
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
    --shadow-hover: 0 8px 32px rgba(0, 0, 0, 0.4);
}

/* Light theme */
[data-theme="light"] {
    --bg-primary: #fafafa;
    --bg-secondary: #f0f0f0;
    --bg-card: #fff;
    --bg-card-hover: #f8f8f8;
    --bg-nav: rgba(250, 250, 250, 0.85);
    --text-primary: #111;
    --text-secondary: #555;
    --text-muted: #999;
    --accent: #2563eb;
    --accent-hover: #1d4ed8;
    --accent-glow: rgba(37, 99, 235, 0.1);
    --border: #e0e0e0;
    --tag-bg: #e0ecff;
    --tag-text: #1e40af;
    --timeline-line: #e0e0e0;
    --timeline-dot: #2563eb;
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.06);
    --shadow-hover: 0 8px 32px rgba(0, 0, 0, 0.1);
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: var(--font);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background var(--transition), color var(--transition);
    -webkit-font-smoothing: antialiased;
}

a {
    color: inherit;
    text-decoration: none;
}

img {
    max-width: 100%;
    display: block;
}

/* ===== Container ===== */
.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

/* ===== Navigation ===== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: var(--bg-nav);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    transition: background var(--transition), border-color var(--transition);
}

.nav__container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 var(--space-lg);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.nav__logo {
    font-size: 1.25rem;
    font-weight: 700;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--text-primary);
    color: var(--bg-primary);
    border-radius: var(--radius-sm);
    transition: background var(--transition), color var(--transition);
}

.nav__links {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    list-style: none;
}

.nav__link {
    font-size: 0.875rem;
    font-weight: 500;
    padding: var(--space-xs) var(--space-sm);
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    transition: color var(--transition), background var(--transition);
    letter-spacing: 0.02em;
}

.nav__link:hover,
.nav__link.active {
    color: var(--text-primary);
}

.nav__link.active {
    text-decoration: underline;
    text-underline-offset: 4px;
    text-decoration-color: var(--accent);
    text-decoration-thickness: 2px;
}

/* Mobile nav toggle */
.nav__mobile-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-xs);
    z-index: 1001;
}

.nav__mobile-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: var(--transition);
}

.nav__mobile-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.nav__mobile-toggle.active span:nth-child(2) {
    opacity: 0;
}

.nav__mobile-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* Theme toggle */
.theme-toggle {
    background: none;
    border: 1px solid var(--border);
    border-radius: 50px;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-secondary);
    transition: color var(--transition), border-color var(--transition), background var(--transition);
}

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

[data-theme="dark"] .theme-toggle__icon--sun { display: none; }
[data-theme="dark"] .theme-toggle__icon--moon { display: block; }
[data-theme="light"] .theme-toggle__icon--sun { display: block; }
[data-theme="light"] .theme-toggle__icon--moon { display: none; }

/* ===== Hero ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: var(--space-xl) var(--space-lg);
    position: relative;
}

.hero__content {
    max-width: 700px;
}

.hero__name {
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.1;
    margin-bottom: var(--space-md);
}

.hero__title {
    font-size: clamp(1.1rem, 2.5vw, 1.4rem);
    color: var(--text-secondary);
    font-weight: 300;
    margin-bottom: var(--space-xl);
    min-height: 2em;
}

.hero__typed {
    color: var(--accent);
    font-weight: 500;
}

.hero__cursor {
    color: var(--accent);
    animation: blink 1s infinite;
    font-weight: 100;
}

@keyframes blink {
    0%, 50% { opacity: 1; }
    51%, 100% { opacity: 0; }
}

.hero__socials {
    display: flex;
    gap: var(--space-md);
    justify-content: center;
    margin-bottom: var(--space-2xl);
}

.hero__social {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--border);
    border-radius: 50%;
    color: var(--text-secondary);
    transition: color var(--transition), border-color var(--transition), background var(--transition), transform var(--transition);
}

.hero__social:hover {
    color: var(--accent);
    border-color: var(--accent);
    background: var(--accent-glow);
    transform: translateY(-3px);
}

.hero__scroll {
    position: absolute;
    bottom: var(--space-xl);
    left: 50%;
    transform: translateX(-50%);
    color: var(--text-muted);
    animation: bounce 2s infinite;
    transition: color var(--transition);
}

.hero__scroll:hover {
    color: var(--accent);
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateX(-50%) translateY(0); }
    40% { transform: translateX(-50%) translateY(-8px); }
    60% { transform: translateX(-50%) translateY(-4px); }
}

/* ===== Sections ===== */
.section {
    padding: var(--space-2xl) 0;
}

.section--alt {
    background: var(--bg-secondary);
    transition: background var(--transition);
}

.section__title {
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: var(--space-xl);
    letter-spacing: -0.02em;
    position: relative;
}

.section__title::after {
    content: '';
    display: block;
    width: 48px;
    height: 3px;
    background: var(--accent);
    margin: var(--space-sm) auto 0;
    border-radius: 2px;
}

/* ===== About ===== */
.about {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: var(--space-xl);
    align-items: start;
}

.about__image-placeholder {
    width: 280px;
    height: 320px;
    background: var(--bg-card);
    border: 2px dashed var(--border);
    border-radius: var(--radius-lg);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    color: var(--text-muted);
    transition: background var(--transition), border-color var(--transition);
}

.about__text p {
    color: var(--text-secondary);
    margin-bottom: var(--space-md);
    font-size: 1.05rem;
    line-height: 1.8;
    transition: color var(--transition);
}

.about__text strong {
    color: var(--text-primary);
}

/* ===== Skills ===== */
.skills {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-lg);
}

.skills__category {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    transition: background var(--transition), border-color var(--transition), box-shadow var(--transition);
}

.skills__category:hover {
    box-shadow: var(--shadow);
}

.skills__category-title {
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--accent);
    margin-bottom: var(--space-md);
}

.skills__tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.skills__tag {
    background: var(--tag-bg);
    color: var(--tag-text);
    padding: 6px 14px;
    border-radius: 50px;
    font-size: 0.85rem;
    font-weight: 500;
    transition: background var(--transition), color var(--transition);
}

/* ===== Timeline (Education & Experience) ===== */
.timeline {
    position: relative;
    max-width: 700px;
    margin: 0 auto;
    padding-left: var(--space-lg);
}

.timeline::before {
    content: '';
    position: absolute;
    left: 7px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--timeline-line);
    transition: background var(--transition);
}

.timeline__item {
    position: relative;
    padding-bottom: var(--space-xl);
}

.timeline__item:last-child {
    padding-bottom: 0;
}

.timeline__dot {
    position: absolute;
    left: calc(-1 * var(--space-lg) + 1px);
    top: 6px;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--timeline-dot);
    border: 3px solid var(--bg-primary);
    box-shadow: 0 0 0 2px var(--timeline-dot);
    transition: background var(--transition), border-color var(--transition);
}

.section--alt .timeline__dot {
    border-color: var(--bg-secondary);
}

.timeline__content {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    transition: background var(--transition), border-color var(--transition), box-shadow var(--transition);
}

.timeline__content:hover {
    box-shadow: var(--shadow);
}

.timeline__date {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--accent);
    letter-spacing: 0.04em;
}

.timeline__title {
    font-size: 1.15rem;
    font-weight: 600;
    margin-top: var(--space-xs);
}

.timeline__subtitle {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-top: 2px;
    transition: color var(--transition);
}

.timeline__text {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-top: var(--space-sm);
    transition: color var(--transition);
}

/* ===== Projects ===== */
.projects {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--space-lg);
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: background var(--transition), border-color var(--transition), box-shadow var(--transition), transform var(--transition);
}

.project-card:hover {
    box-shadow: var(--shadow-hover);
    transform: translateY(-4px);
}

.project-card__image {
    height: 200px;
    background: var(--bg-secondary);
    overflow: hidden;
    transition: background var(--transition);
}

.project-card__placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    font-size: 1.1rem;
    font-weight: 500;
    letter-spacing: 0.02em;
}

.project-card__body {
    padding: var(--space-lg);
}

.project-card__title {
    font-size: 1.15rem;
    font-weight: 600;
    margin-bottom: var(--space-sm);
}

.project-card__text {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-bottom: var(--space-md);
    transition: color var(--transition);
}

.project-card__tags {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    margin-bottom: var(--space-md);
}

.project-card__tags span {
    background: var(--tag-bg);
    color: var(--tag-text);
    padding: 3px 10px;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 500;
    transition: background var(--transition), color var(--transition);
}

.project-card__links {
    display: flex;
    gap: var(--space-md);
}

.project-card__link {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: color var(--transition);
}

.project-card__link:hover {
    color: var(--accent);
}

/* ===== Resume ===== */
.resume {
    text-align: center;
    max-width: 500px;
    margin: 0 auto;
}

.resume__text {
    color: var(--text-secondary);
    font-size: 1.05rem;
    margin-bottom: var(--space-lg);
    transition: color var(--transition);
}

.resume__actions {
    display: flex;
    gap: var(--space-md);
    justify-content: center;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    padding: 12px 28px;
    border-radius: 50px;
    font-size: 0.95rem;
    font-weight: 600;
    transition: all var(--transition);
    cursor: pointer;
    border: none;
}

.btn--primary {
    background: var(--accent);
    color: #fff;
}

.btn--primary:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 4px 16px rgba(59, 130, 246, 0.3);
}

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

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

/* ===== Footer ===== */
.footer {
    border-top: 1px solid var(--border);
    padding: var(--space-lg) 0;
    transition: border-color var(--transition);
}

.footer__content {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.footer__content p {
    color: var(--text-muted);
    font-size: 0.85rem;
    transition: color var(--transition);
}

.footer__socials {
    display: flex;
    gap: var(--space-md);
}

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

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

/* ===== Scroll Reveal Animation ===== */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav__mobile-toggle {
        display: flex;
    }

    .nav__links {
        position: fixed;
        top: 0;
        right: -100%;
        width: 280px;
        height: 100vh;
        background: var(--bg-primary);
        flex-direction: column;
        align-items: flex-start;
        padding: 80px var(--space-lg) var(--space-lg);
        gap: var(--space-xs);
        transition: right var(--transition);
        border-left: 1px solid var(--border);
    }

    .nav__links.open {
        right: 0;
    }

    .nav__link {
        font-size: 1rem;
        padding: var(--space-sm) 0;
    }

    .about {
        grid-template-columns: 1fr;
        justify-items: center;
        text-align: center;
    }

    .hero__name {
        font-size: 2.2rem;
    }

    .projects {
        grid-template-columns: 1fr;
    }

    .skills {
        grid-template-columns: 1fr;
    }

    .footer__content {
        flex-direction: column;
        gap: var(--space-md);
        text-align: center;
    }

    .timeline {
        padding-left: var(--space-lg);
    }
}

@media (max-width: 480px) {
    .hero__name {
        font-size: 1.8rem;
    }

    .section {
        padding: var(--space-xl) 0;
    }

    .resume__actions {
        flex-direction: column;
        align-items: center;
    }
}