/* ============================================================
   Ruslan Krupenko — personal page
   Modern, responsive, dark / light themed. No framework.
   ============================================================ */

/* ---------- Theme tokens ---------- */
:root {
    --accent:        #00add8;   /* Go cyan */
    --accent-2:      #4f9dff;
    --accent-soft:   rgba(0, 173, 216, 0.12);

    --bg:            #0d1117;
    --bg-elev:       #161b22;
    --bg-elev-2:     #1c2330;
    --border:        #263042;
    --border-soft:   #1e2733;

    --text:          #e6edf3;
    --text-muted:    #9aa7b4;
    --text-faint:    #6b7784;

    --shadow:        0 10px 30px -12px rgba(0, 0, 0, 0.6);
    --radius:        14px;
    --radius-sm:     10px;

    --maxw:          1080px;
    --font-sans:     'Inter', system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
    --font-display:  'Space Grotesk', var(--font-sans);
}

html[data-theme="light"] {
    --accent:        #0b8fb3;
    --accent-2:      #2b6fd6;
    --accent-soft:   rgba(11, 143, 179, 0.10);

    --bg:            #f7f9fc;
    --bg-elev:       #ffffff;
    --bg-elev-2:     #ffffff;
    --border:        #e2e8f0;
    --border-soft:   #eef2f7;

    --text:          #0f1b2d;
    --text-muted:    #4a5a6c;
    --text-faint:    #7b8a9a;

    --shadow:        0 12px 28px -16px rgba(15, 27, 45, 0.25);
}

/* ---------- Reset / base ---------- */
*, *::before, *::after { box-sizing: border-box; }

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    margin: 0;
    font-family: var(--font-sans);
    background: var(--bg);
    color: var(--text);
    line-height: 1.65;
    font-size: clamp(15px, 0.9rem + 0.2vw, 17px);
    -webkit-font-smoothing: antialiased;
    transition: background-color 0.3s ease, color 0.3s ease;
}

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    * { animation: none !important; transition: none !important; }
}

h1, h2, h3 { font-family: var(--font-display); line-height: 1.15; font-weight: 600; }
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
strong { color: var(--text); font-weight: 600; }

.container {
    width: 100%;
    max-width: var(--maxw);
    margin-inline: auto;
    padding-inline: clamp(1.1rem, 4vw, 2rem);
}

.skip-link {
    position: absolute;
    left: -999px;
    top: 0;
    background: var(--accent);
    color: #001018;
    padding: 0.6rem 1rem;
    border-radius: 0 0 var(--radius-sm) 0;
    z-index: 200;
}
.skip-link:focus { left: 0; }

/* ---------- Header / nav ---------- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: color-mix(in srgb, var(--bg) 82%, transparent);
    backdrop-filter: saturate(140%) blur(12px);
    border-bottom: 1px solid var(--border-soft);
}

.nav {
    display: flex;
    align-items: center;
    gap: 1rem;
    height: 64px;
}
.nav-right {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.brand { display: inline-flex; align-items: center; gap: 0.6rem; font-weight: 600; }
.brand-mark {
    display: grid;
    place-items: center;
    width: 34px; height: 34px;
    border-radius: 9px;
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    color: #001018;
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 0.9rem;
}
.brand-name { font-family: var(--font-display); font-size: 1rem; }

.nav-menu {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    list-style: none;
    margin: 0 0 0 auto; padding: 0;
}
.nav-menu a {
    padding: 0.45rem 0.7rem;
    border-radius: 8px;
    color: var(--text-muted);
    font-size: 0.93rem;
    font-weight: 500;
    transition: color 0.2s, background 0.2s;
}
.nav-menu a:hover { color: var(--text); background: var(--accent-soft); }
.nav-menu a.active { color: var(--accent); }

.theme-toggle {
    display: grid;
    place-items: center;
    width: 38px; height: 38px;
    border: 1px solid var(--border);
    background: var(--bg-elev);
    color: var(--text-muted);
    border-radius: 9px;
    cursor: pointer;
    transition: color 0.2s, border-color 0.2s, transform 0.2s;
}
.theme-toggle:hover { color: var(--accent); border-color: var(--accent); }
.theme-toggle svg { stroke: currentColor; stroke-width: 2; fill: none; stroke-linecap: round; stroke-linejoin: round; }
/* Show the mode you'll switch TO: sun in dark mode, moon in light mode. */
.icon-sun { display: block; }
.icon-moon { display: none; }
html[data-theme="light"] .icon-sun { display: none; }
html[data-theme="light"] .icon-moon { display: block; }

.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 42px; height: 42px;
    background: transparent;
    border: 1px solid var(--border);
    border-radius: 9px;
    cursor: pointer;
    padding: 0 10px;
}
.nav-toggle span {
    height: 2px;
    background: var(--text);
    border-radius: 2px;
    transition: transform 0.25s, opacity 0.25s;
}

/* ---------- Buttons ---------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.7rem 1.3rem;
    border-radius: 10px;
    font-weight: 600;
    font-size: 0.95rem;
    border: 1px solid transparent;
    cursor: pointer;
    transition: transform 0.15s, box-shadow 0.2s, background 0.2s, border-color 0.2s;
}
.btn-primary {
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    color: #001018;
    box-shadow: 0 8px 22px -10px var(--accent);
}
.btn-primary:hover { transform: translateY(-2px); }
.btn-ghost {
    border-color: var(--border);
    color: var(--text);
    background: var(--bg-elev);
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

/* ---------- Hero ---------- */
.hero {
    position: relative;
    display: grid;
    grid-template-columns: 1.4fr 1fr;
    gap: 0 clamp(2rem, 5vw, 4rem);
    align-items: start;
    padding-top: clamp(3rem, 6vw, 4.5rem);
    padding-bottom: clamp(2.5rem, 6vw, 4rem);
}
.hero > * { min-width: 0; }
#main { overflow-x: clip; }

.hero-eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    margin: 0 0 1rem;
    padding: 0.35rem 0.8rem;
    border: 1px solid var(--border);
    border-radius: 999px;
    background: var(--bg-elev);
    color: var(--text-muted);
    font-size: 0.82rem;
    font-weight: 500;
}
.status-dot {
    width: 8px; height: 8px;
    border-radius: 50%;
    background: #2ecc71;
    box-shadow: 0 0 0 0 rgba(46, 204, 113, 0.5);
    animation: pulse 2.2s infinite;
}
@keyframes pulse {
    0%   { box-shadow: 0 0 0 0 rgba(46, 204, 113, 0.5); }
    70%  { box-shadow: 0 0 0 8px rgba(46, 204, 113, 0); }
    100% { box-shadow: 0 0 0 0 rgba(46, 204, 113, 0); }
}

.hero-title {
    margin: 0;
    font-size: clamp(2.4rem, 6vw, 3.8rem);
    letter-spacing: -0.02em;
}
.hero-role {
    margin: 0.3rem 0 0;
    font-family: var(--font-display);
    font-size: clamp(1.1rem, 2.4vw, 1.5rem);
    font-weight: 600;
    background: linear-gradient(120deg, var(--accent), var(--accent-2));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}
.hero-tagline {
    margin: 1.1rem 0 0;
    max-width: min(46ch, 100%);
    color: var(--text-muted);
    font-size: 1.05rem;
}

.hero-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem 1.4rem;
    list-style: none;
    margin: 1.4rem 0 0;
    padding: 0;
    color: var(--text-muted);
    font-size: 0.92rem;
}
.hero-meta li { display: inline-flex; align-items: center; gap: 0.45rem; }
.hero-meta svg { stroke: var(--accent); stroke-width: 2; fill: none; stroke-linecap: round; stroke-linejoin: round; }

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.8rem;
    margin-top: 1.8rem;
}

.hero-photo { display: flex; flex-direction: column; align-items: center; margin-top: 1rem; }
.photo-frame {
    position: relative;
    width: min(360px, 88%);
}
.photo-frame img {
    width: 100%;
    height: auto;
    display: block;
    filter: drop-shadow(0 22px 26px rgba(2, 8, 20, 0.45));
}
html[data-theme="light"] .photo-frame img {
    filter: drop-shadow(0 20px 24px rgba(15, 27, 45, 0.22));
}

/* ---------- Sections ---------- */
.section {
    padding-top: clamp(3rem, 7vw, 5rem);
    padding-bottom: clamp(1rem, 3vw, 2rem);
    scroll-margin-top: 80px;
}
.section-title {
    display: flex;
    align-items: baseline;
    gap: 0.7rem;
    margin: 0 0 2rem;
    font-size: clamp(1.5rem, 3.5vw, 2.1rem);
    letter-spacing: -0.01em;
}
.section-index {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--accent);
    font-family: var(--font-display);
}

/* ---------- Hero thought bubble (quote) ---------- */
.thought {
    grid-column: 1 / -1;
    justify-self: end;
    position: relative;
    z-index: 3;
    width: 100%;
    max-width: 620px;
    margin: 0 0 2.6rem;
    padding: 0.5rem 1.4rem 0.6rem;
    background: color-mix(in srgb, var(--bg-elev) 80%, transparent);
    border: 1px solid var(--border);
    border-radius: 34px;
    box-shadow: var(--shadow);
    backdrop-filter: blur(8px);
}
/* comic thought-tail: three shrinking bubbles arcing down toward the head */
.thought::before,
.thought::after,
.think-tail {
    content: "";
    position: absolute;
    border-radius: 50%;
    background: color-mix(in srgb, var(--bg-elev) 80%, transparent);
    border: 1px solid var(--border);
    backdrop-filter: blur(8px);
}
.thought::before { width: 18px; height: 18px; bottom: -13px; left: 46%; }
.think-tail      { width: 12px; height: 12px; bottom: -28px; left: 50%; }
.thought::after  { width: 8px;  height: 8px;  bottom: -44px; left: 54%; }
.thought blockquote {
    margin: 0;
    font-family: 'Kalam', var(--font-display);
    font-size: 1.12rem;
    line-height: 1.3;
    font-weight: 400;
    color: var(--text);
    overflow-wrap: break-word;
}
.thought blockquote::before { content: "\201C"; }
.thought blockquote::after  { content: "\201D"; }
.thought figcaption {
    position: absolute;
    right: 40px;
    bottom: 0.5rem;
    margin: 0;
    color: var(--accent);
    font-family: 'Kalam', var(--font-display);
    font-size: 0.88rem;
    font-weight: 700;
    white-space: nowrap;
}

/* ---------- About ---------- */
.about-grid {
    display: grid;
    grid-template-columns: 1.6fr 1fr;
    gap: clamp(1.5rem, 4vw, 3rem);
    align-items: start;
}
.about-text p { margin: 0 0 1rem; color: var(--text-muted); }
.about-text p:last-child { margin-bottom: 0; }

.about-stats {
    display: grid;
    gap: 0.8rem;
    list-style: none;
    margin: 0; padding: 0;
}
.about-stats li {
    display: flex;
    align-items: baseline;
    gap: 0.8rem;
    padding: 1rem 1.2rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--bg-elev);
}
.stat-num {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent);
    min-width: 3.2ch;
}
.stat-label { color: var(--text-muted); font-size: 0.92rem; }

/* ---------- Chips ---------- */
.chips {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    list-style: none;
    margin: 0; padding: 0;
}
.chips li {
    padding: 0.35rem 0.75rem;
    border: 1px solid var(--border);
    border-radius: 999px;
    background: var(--bg-elev-2);
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 500;
}
.chips-sm li { font-size: 0.78rem; padding: 0.25rem 0.6rem; }

/* ---------- Skills ---------- */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 1rem;
}
.skill-card {
    padding: 1.3rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--bg-elev);
    transition: border-color 0.2s, transform 0.2s;
}
.skill-card:hover { border-color: var(--accent); transform: translateY(-3px); }
.skill-card h3 {
    margin: 0 0 0.9rem;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-faint);
}

/* ---------- Experience timeline ---------- */
.timeline { position: relative; display: grid; gap: 1rem; }
.tl-item {
    position: relative;
    display: grid;
    grid-template-columns: 24px 1fr;
    gap: 1rem;
}
.tl-marker {
    position: relative;
    display: flex;
    justify-content: center;
}
.tl-marker::before {
    content: "";
    width: 14px; height: 14px;
    margin-top: 1.6rem;
    border-radius: 50%;
    background: var(--accent);
    box-shadow: 0 0 0 4px var(--accent-soft);
    z-index: 1;
}
.tl-item:not(:last-child) .tl-marker::after {
    content: "";
    position: absolute;
    top: 2.6rem;
    bottom: -1rem;
    width: 2px;
    background: var(--border);
}
.tl-body {
    padding: 1.3rem 1.4rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--bg-elev);
    transition: border-color 0.2s;
}
.tl-body:hover { border-color: var(--accent); }
.tl-head {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: baseline;
    gap: 0.3rem 1rem;
}
.tl-head h3 { margin: 0; font-size: 1.15rem; }
.tl-date {
    color: var(--accent);
    font-size: 0.82rem;
    font-weight: 600;
    font-family: var(--font-display);
    white-space: nowrap;
}
.tl-company { margin: 0.2rem 0 0.7rem; color: var(--text-faint); font-size: 0.9rem; font-weight: 500; }
.tl-body p:not(.tl-company) { margin: 0 0 0.9rem; color: var(--text-muted); font-size: 0.95rem; }

/* ---------- Projects ---------- */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.2rem;
}
.project-card {
    display: flex;
    flex-direction: column;
    padding: 1.6rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: linear-gradient(180deg, var(--bg-elev), var(--bg));
    transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}
.project-card:hover {
    border-color: var(--accent);
    transform: translateY(-4px);
    box-shadow: var(--shadow);
}
.project-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.8rem;
}
.project-top h3 { margin: 0; font-size: 1.3rem; }
.project-link {
    display: grid;
    place-items: center;
    width: 38px; height: 38px;
    border: 1px solid var(--border);
    border-radius: 10px;
    color: var(--text-muted);
    transition: color 0.2s, border-color 0.2s, transform 0.2s;
}
.project-link:hover { color: var(--accent); border-color: var(--accent); transform: translate(2px, -2px); }
.project-link svg { stroke: currentColor; stroke-width: 2; fill: none; stroke-linecap: round; stroke-linejoin: round; }
.project-desc { margin: 0 0 1.2rem; color: var(--text-muted); font-size: 0.95rem; flex-grow: 1; }

/* ---------- Education ---------- */
.edu-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1.2rem;
}
.edu-card {
    padding: 1.5rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--bg-elev);
    transition: border-color 0.2s, transform 0.2s;
}
.edu-card:hover { border-color: var(--accent); transform: translateY(-3px); }
.edu-cert {
    background:
        radial-gradient(circle at 100% 0%, var(--accent-soft), transparent 55%),
        var(--bg-elev);
}
.edu-badge {
    display: inline-block;
    margin-bottom: 0.8rem;
    padding: 0.25rem 0.7rem;
    border-radius: 999px;
    background: var(--accent-soft);
    color: var(--accent);
    font-size: 0.72rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
}
.edu-card h3 { margin: 0 0 0.4rem; font-size: 1.1rem; }
.edu-org { margin: 0; color: var(--text-muted); font-size: 0.92rem; }
.edu-year { margin: 0.3rem 0 0; color: var(--text-faint); font-size: 0.85rem; font-weight: 500; }
.edu-note { margin: 0.6rem 0 0; color: var(--text-faint); font-size: 0.85rem; }

/* ---------- Contact ---------- */
.contact-box {
    padding: clamp(1.6rem, 5vw, 2.6rem);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background:
        radial-gradient(circle at 0% 0%, var(--accent-soft), transparent 45%),
        var(--bg-elev);
}
.contact-lead {
    margin: 0 0 1.8rem;
    max-width: 52ch;
    font-size: 1.1rem;
    color: var(--text-muted);
}
.contact-links {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 0.9rem;
}
.contact-item {
    display: flex;
    align-items: center;
    gap: 0.9rem;
    padding: 1rem 1.2rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg);
    transition: border-color 0.2s, transform 0.2s;
}
.contact-item:hover { border-color: var(--accent); transform: translateY(-2px); }
.contact-item svg { stroke: var(--accent); stroke-width: 1.8; fill: none; stroke-linecap: round; stroke-linejoin: round; flex-shrink: 0; }
.contact-item span { display: flex; flex-direction: column; font-size: 0.92rem; color: var(--text-muted); }
.contact-item strong { font-size: 0.76rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--text-faint); font-weight: 600; }

/* ---------- Footer ---------- */
.site-footer {
    margin-top: clamp(3rem, 7vw, 5rem);
    border-top: 1px solid var(--border-soft);
    padding-block: 1.6rem;
}
.footer-inner {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 0.5rem;
    color: var(--text-faint);
    font-size: 0.85rem;
}
.footer-inner p { margin: 0; }

/* ---------- Reveal on scroll ---------- */
.reveal {
    opacity: 0;
    transform: translateY(18px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.in { opacity: 1; transform: none; }

/* ---------- Responsive ---------- */
@media (max-width: 860px) {
    .hero { grid-template-columns: minmax(0, 1fr); text-align: left; }
    .thought { order: -2; justify-self: stretch; width: 100%; max-width: 100%; margin: 0 0 1.6rem; }
    .thought figcaption { white-space: normal; }
    .thought::before { left: 30%; }
    .think-tail      { left: 40%; }
    .thought::after  { left: 47%; }
    .hero-photo { order: -1; justify-self: start; margin-top: 0; }
    .photo-frame { width: min(240px, 60%); }
    .about-grid { grid-template-columns: 1fr; }
    .about-stats { grid-template-columns: repeat(3, 1fr); }
    .about-stats li { flex-direction: column; align-items: flex-start; gap: 0.2rem; }
}

@media (max-width: 720px) {
    .nav-toggle { display: flex; }
    .nav-menu {
        position: fixed;
        inset: 64px 0 auto 0;
        flex-direction: column;
        align-items: stretch;
        gap: 0.2rem;
        padding: 1rem clamp(1.1rem, 4vw, 2rem) 1.4rem;
        background: var(--bg-elev);
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow);
        transform: translateY(-120%);
        transition: transform 0.3s ease;
        visibility: hidden;
    }
    .nav-menu.open { transform: translateY(0); visibility: visible; }
    .nav-menu a { padding: 0.7rem 0.6rem; font-size: 1rem; }
    .nav-right { margin-left: auto; }
}

@media (max-width: 560px) {
    /* On narrow phones the signature drops to its own row so it never
       collides with the last line of the quote. */
    .thought figcaption {
        position: static;
        display: block;
        text-align: right;
        margin-top: 0.15rem;
    }
}

@media (max-width: 480px) {
    .about-stats { grid-template-columns: 1fr; }
    .about-stats li { flex-direction: row; align-items: baseline; }
    .tl-head { flex-direction: column; }
}