/* ==========================================================================
   MAIN STYLESHEET — Bikalpa Chaudhary, Java Developer Portfolio
   Structure:
     1. Design tokens (CSS custom properties)
     2. Reset & base styles
     3. Utilities (container, section, buttons, headings)
     4. Header & navigation
     5. Hero
     6. About
     7. Skills
     8. Projects
     9. Experience timeline
    10. Contact
    11. Footer
    12. Back-to-top & scroll progress
    13. Reveal-on-scroll animations
    14. Media queries (responsive)
    15. Accessibility preferences
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. Design tokens
   -------------------------------------------------------------------------- */
:root {
    /* Color palette */
    --color-bg: #0d1117;
    --color-bg-alt: #161b22;
    --color-surface: #1c2330;
    --color-border: #2a3342;
    --color-text: #e6edf3;
    --color-text-muted: #9aa7b5;
    --color-accent: #f8981d; /* Java orange */
    --color-accent-strong: #e07b00;
    --color-accent-2: #5382a1; /* Java blue */

    /* Typography */
    --font-sans: "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: "Consolas", "SFMono-Regular", Menlo, monospace;

    /* Layout */
    --container-max: 1100px;
    --container-pad: 5%;
    --section-space: 96px;

    /* Misc */
    --radius: 14px;
    --shadow-accent: 0 6px 18px rgba(248, 152, 29, 0.25);
    --transition: 200ms ease;
}

/* --------------------------------------------------------------------------
   2. Reset & base styles
   -------------------------------------------------------------------------- */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.65;
    -webkit-font-smoothing: antialiased;
}

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

ul,
ol {
    list-style: none;
}

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

button {
    font: inherit;
    color: inherit;
    background: none;
    border: none;
    cursor: pointer;
}

/* Consistent, visible focus for keyboard users */
:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 3px;
    border-radius: 4px;
}

/* Hidden SVG sprite definitions */
.svg-sprite {
    position: absolute;
    width: 0;
    height: 0;
    overflow: hidden;
}

/* --------------------------------------------------------------------------
   3. Utilities
   -------------------------------------------------------------------------- */
.container {
    width: 100%;
    max-width: var(--container-max);
    margin-inline: auto;
    padding-inline: var(--container-pad);
}

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

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

.section__heading {
    font-size: clamp(1.6rem, 3.5vw, 2.1rem);
    margin-bottom: 48px;
    position: relative;
    width: fit-content;
}

.section__heading::after {
    content: "";
    position: absolute;
    left: 0;
    bottom: -10px;
    width: 55%;
    height: 4px;
    border-radius: 4px;
    background: linear-gradient(90deg, var(--color-accent), var(--color-accent-2));
}

.btn {
    display: inline-block;
    padding: 12px 28px;
    border-radius: 8px;
    font-weight: 600;
    transition: transform var(--transition), box-shadow var(--transition),
    border-color var(--transition), color var(--transition);
}

.btn:hover {
    transform: translateY(-2px);
}

.btn--primary {
    background: linear-gradient(90deg, var(--color-accent), var(--color-accent-strong));
    color: #111;
    box-shadow: var(--shadow-accent);
}

.btn--ghost {
    border: 1px solid var(--color-border);
    color: var(--color-text);
}

.btn--ghost:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
}

/* --------------------------------------------------------------------------
   4. Header & navigation
   -------------------------------------------------------------------------- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(13, 17, 23, 0.85);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.nav__logo {
    font-weight: 700;
    font-size: 1.2rem;
    letter-spacing: 0.5px;
}

.nav__logo-bracket {
    color: var(--color-accent);
    font-family: var(--font-mono);
}

.nav__menu {
    display: flex;
    gap: 28px;
}

.nav__link {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    transition: color var(--transition);
}

.nav__link:hover,
.nav__link.is-active {
    color: var(--color-accent);
}

/* Hamburger toggle — hidden on desktop */
.nav__toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 6px;
}

.nav__toggle-bar {
    width: 24px;
    height: 2px;
    border-radius: 2px;
    background: var(--color-text);
    transition: transform var(--transition), opacity var(--transition);
}

/* Animated "X" when the menu is open */
.nav__toggle[aria-expanded="true"] .nav__toggle-bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.nav__toggle[aria-expanded="true"] .nav__toggle-bar:nth-child(2) {
    opacity: 0;
}

.nav__toggle[aria-expanded="true"] .nav__toggle-bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* --------------------------------------------------------------------------
   5. Hero
   -------------------------------------------------------------------------- */
.hero {
    min-height: calc(100vh - 64px);
    display: flex;
    align-items: center;
    background: radial-gradient(600px circle at 85% 20%, rgba(83, 130, 161, 0.18), transparent 60%),
    radial-gradient(500px circle at 10% 80%, rgba(248, 152, 29, 0.12), transparent 60%);
}

.hero__inner {
    max-width: 760px;
}

.hero__greeting {
    color: var(--color-accent);
    font-family: var(--font-mono);
    font-size: 0.95rem;
    letter-spacing: 1px;
}

.hero__title {
    font-size: clamp(2.4rem, 6vw, 3.8rem);
    line-height: 1.15;
    margin-block: 12px;
}

.hero__accent {
    color: var(--color-accent);
}

.hero__subtitle {
    font-size: clamp(1.1rem, 3vw, 1.5rem);
    font-weight: 600;
    color: var(--color-text-muted);
    min-height: 1.9em;
}

.hero__cursor {
    color: var(--color-accent);
    animation: cursor-blink 1s steps(1) infinite;
}

@keyframes cursor-blink {
    50% {
        opacity: 0;
    }
}

.hero__description {
    color: var(--color-text-muted);
    max-width: 560px;
    margin-block: 22px 32px;
}

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

.hero__actions {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
}

.hero__socials {
    display: flex;
    gap: 20px;
    margin-top: 36px;
}

.hero__socials a {
    color: var(--color-text-muted);
    padding: 6px;
    transition: color var(--transition), transform var(--transition);
}

.hero__socials a:hover {
    color: var(--color-accent);
    transform: translateY(-3px);
}

/* --------------------------------------------------------------------------
   6. About
   -------------------------------------------------------------------------- */
.about {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 56px;
    align-items: center;
}

.about__text p + p {
    margin-top: 16px;
}

.about__text p {
    color: var(--color-text-muted);
}

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

.about__stats {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 18px;
}

.stat {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 24px;
    text-align: center;
    transition: transform var(--transition), border-color var(--transition);
}

.stat:hover {
    transform: translateY(-4px);
    border-color: var(--color-accent-2);
}

.stat__value {
    font-size: 1.9rem;
    font-weight: 700;
    color: var(--color-accent);
}

.stat__label {
    color: var(--color-text-muted);
    font-size: 0.9rem;
}

/* --------------------------------------------------------------------------
   7. Skills
   -------------------------------------------------------------------------- */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 22px;
}

.skill-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 26px;
    transition: transform var(--transition), border-color var(--transition);
}

.skill-card:hover {
    transform: translateY(-5px);
    border-color: var(--color-accent-2);
}

.skill-card__title {
    font-size: 1.05rem;
    margin-bottom: 14px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--color-border);
}

.skill-card__list li {
    color: var(--color-text-muted);
    font-size: 0.92rem;
    padding-block: 4px;
}

.skill-card__list li::before {
    content: "▹";
    color: var(--color-accent);
    margin-right: 10px;
}

/* --------------------------------------------------------------------------
   8. Projects
   -------------------------------------------------------------------------- */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
}

.project-card {
    display: flex;
    flex-direction: column;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 28px;
    transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
}

.project-card:hover {
    transform: translateY(-5px);
    border-color: var(--color-accent);
    box-shadow: 0 12px 28px rgba(0, 0, 0, 0.35);
}

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

.project-card__icon {
    width: 36px;
    height: 36px;
    color: var(--color-accent);
}

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

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

.project-card__title {
    font-size: 1.2rem;
    margin-block: 16px 8px;
}

.project-card__description {
    color: var(--color-text-muted);
    font-size: 0.94rem;
    flex-grow: 1;
}

.project-card__tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 18px;
}

.project-card__tags li {
    font-family: var(--font-mono);
    font-size: 0.74rem;
    color: var(--color-accent);
    background: rgba(248, 152, 29, 0.08);
    border: 1px solid rgba(248, 152, 29, 0.25);
    padding: 3px 10px;
    border-radius: 20px;
}

/* --------------------------------------------------------------------------
   9. Experience timeline
   -------------------------------------------------------------------------- */
.timeline {
    position: relative;
    margin-left: 8px;
    padding-left: 32px;
    border-left: 2px solid var(--color-border);
}

.timeline__item {
    position: relative;
    padding-bottom: 44px;
}

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

.timeline__item::before {
    content: "";
    position: absolute;
    left: -41px;
    top: 6px;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--color-bg-alt);
    border: 3px solid var(--color-accent);
}

.timeline__date {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--color-accent);
}

.timeline__role {
    font-size: 1.15rem;
    margin-block: 6px 2px;
}

.timeline__org {
    color: var(--color-accent-2);
    font-weight: 600;
    font-size: 0.95rem;
}

.timeline__summary {
    color: var(--color-text-muted);
    font-size: 0.94rem;
    margin-top: 8px;
}

/* --------------------------------------------------------------------------
   10. Contact
   -------------------------------------------------------------------------- */
.contact {
    text-align: center;
}

.contact .section__heading::after {
    left: 50%;
    transform: translateX(-50%);
}

.contact__lead {
    color: var(--color-text-muted);
    max-width: 560px;
    margin: 0 auto 36px;
}

.contact__details {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 14px 32px;
    margin-top: 36px;
    color: var(--color-text-muted);
    font-size: 0.95rem;
}

.contact__details a,
.contact__details li {
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.contact__details svg {
    width: 18px;
    height: 18px;
    color: var(--color-accent);
}

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

/* --------------------------------------------------------------------------
   11. Footer
   -------------------------------------------------------------------------- */
.site-footer {
    border-top: 1px solid var(--color-border);
    padding-block: 28px;
    text-align: center;
    color: var(--color-text-muted);
    font-size: 0.88rem;
}

.site-footer__meta {
    margin-top: 6px;
    font-family: var(--font-mono);
    font-size: 0.8rem;
}

.site-footer__meta a {
    color: var(--color-accent-2);
}

.site-footer__meta a:hover {
    text-decoration: underline;
}

/* --------------------------------------------------------------------------
   12. Back-to-top & scroll progress
   -------------------------------------------------------------------------- */
.back-to-top {
    position: fixed;
    right: 24px;
    bottom: 24px;
    z-index: 90;
    display: grid;
    place-items: center;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    color: var(--color-accent);
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.4);
    transition: transform var(--transition), border-color var(--transition);
}

.back-to-top:hover {
    transform: translateY(-4px);
    border-color: var(--color-accent);
}

.scroll-progress {
    position: fixed;
    top: 0;
    left: 0;
    z-index: 200;
    height: 3px;
    width: 0;
    background: linear-gradient(90deg, var(--color-accent), var(--color-accent-2));
}

/* --------------------------------------------------------------------------
   13. Reveal-on-scroll animations
   Progressive enhancement: content is visible by default; the .is-visible
   pattern only animates when JS adds the initial [data-reveal-hidden] class.
   -------------------------------------------------------------------------- */
[data-reveal] {
    opacity: 1;
}

[data-reveal].is-hidden {
    opacity: 0;
    transform: translateY(28px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

[data-reveal].is-hidden.is-visible {
    opacity: 1;
    transform: translateY(0);
}

/* --------------------------------------------------------------------------
   14. Media queries (responsive)
   -------------------------------------------------------------------------- */
@media (max-width: 800px) {
    :root {
        --section-space: 72px;
    }

    /* Mobile navigation: hamburger + dropdown panel */
    .nav__toggle {
        display: flex;
    }

    .nav__menu {
        position: absolute;
        top: 64px;
        left: 0;
        width: 100%;
        flex-direction: column;
        gap: 4px;
        padding: 16px var(--container-pad) 24px;
        background: var(--color-bg-alt);
        border-bottom: 1px solid var(--color-border);
        transform: translateY(-8px);
        opacity: 0;
        visibility: hidden;
        transition: opacity var(--transition), transform var(--transition), visibility var(--transition);
    }

    .nav__menu.is-open {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav__link {
        display: block;
        padding-block: 10px;
        font-size: 1rem;
    }

    .about {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .hero {
        min-height: 80vh;
    }
}

/* --------------------------------------------------------------------------
   15. Accessibility preferences
   Respect users who opt out of motion in their OS settings.
   -------------------------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    .hero__cursor {
        animation: none;
    }
}