/* ============================================================
   CyberStudy 4E — Base: reset, типографіка, контейнери, prose
   ============================================================ */

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

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

body {
    margin: 0;
    background: var(--cs-bg);
    color: var(--cs-text);
    font-family: var(--cs-font);
    font-size: 16px;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }
iframe { border: 0; }

a { color: var(--cs-accent); text-decoration: none; transition: color .18s ease-out; }
a:hover { color: var(--cs-white); }

::selection { background: rgba(79, 195, 176, .35); color: #fff; }

:focus-visible {
    outline: 2px solid var(--cs-accent);
    outline-offset: 2px;
    border-radius: var(--cs-r-xs);
}

/* Контейнер */
.cs-container {
    max-width: var(--cs-container);
    margin: 0 auto;
    padding-left: var(--cs-pad-x);
    padding-right: var(--cs-pad-x);
}

/* Секції */
.cs-section { padding: var(--cs-section-y) 0; background: var(--cs-bg); }
.cs-section--alt {
    background: var(--cs-alt-grad);
    border-top: 1px solid var(--cs-line-strong);
    border-bottom: 1px solid var(--cs-line-strong);
}
.cs-section--deep { background: linear-gradient(180deg, #0C1424, #070C18); border-top: 1px solid var(--cs-line-strong); border-bottom: 1px solid var(--cs-line-strong); }
.cs-section--light { background: var(--cs-light-bg); color: var(--cs-light-ink); }
.cs-section--light-grad { background: var(--cs-light-grad); color: var(--cs-light-ink); }

/* Типографічні примітиви */
.cs-label {
    font-family: var(--cs-mono);
    font-size: 12px;
    letter-spacing: .22em;
    text-transform: uppercase;
    color: var(--cs-accent);
    margin-bottom: 16px;
}
.cs-section--light .cs-label,
.cs-section--light-grad .cs-label { color: var(--cs-light-accent); }

.cs-h1 {
    font-size: clamp(2.4rem, 5vw, 4rem);
    line-height: 1.04;
    letter-spacing: -.035em;
    font-weight: 800;
    margin: 0 0 22px;
    color: var(--cs-white);
    text-wrap: balance;
}
.cs-h2 {
    font-size: clamp(1.7rem, 3vw, 2.375rem);
    line-height: 1.14;
    letter-spacing: -.03em;
    font-weight: 800;
    margin: 0;
    color: var(--cs-white);
}
.cs-section--light .cs-h2,
.cs-section--light-grad .cs-h2 { color: var(--cs-light-ink); }

.cs-h3 {
    font-size: 21px;
    font-weight: 800;
    line-height: 1.22;
    margin: 0 0 11px;
    color: var(--cs-white);
}
.cs-lead {
    font-size: clamp(1rem, 1.5vw, 1.125rem);
    line-height: 1.62;
    color: var(--cs-text-body);
}
.cs-note { font-size: 12.5px; line-height: 1.55; color: var(--cs-text-note); }

.cs-mono { font-family: var(--cs-mono); }

/* Заголовок секції: label + h2 + lead */
.cs-section-head { margin-bottom: 36px; }
.cs-section-head--split {
    display: flex;
    justify-content: space-between;
    align-items: end;
    gap: 32px;
    flex-wrap: wrap;
}
.cs-section-head__side {
    font-size: 16px;
    line-height: 1.65;
    color: var(--cs-text-body);
    margin: 0;
    max-width: 420px;
}

/* ── Prose (markdown-контент) ── */
.cs-prose { font-size: 17px; line-height: 1.72; color: var(--cs-text-body); }
.cs-prose > :first-child { margin-top: 0; }
.cs-prose > :last-child { margin-bottom: 0; }
.cs-prose p { margin: 0 0 18px; }
.cs-prose strong, .cs-prose b { color: var(--cs-text); font-weight: 700; }
.cs-prose a { color: var(--cs-accent); text-decoration: underline; text-decoration-color: rgba(111, 230, 205, .35); text-underline-offset: 3px; }
.cs-prose a:hover { color: #fff; }
.cs-prose ul, .cs-prose ol { padding-left: 22px; margin: 0 0 18px; }
.cs-prose li { margin-bottom: 8px; }
.cs-prose li::marker { color: var(--cs-accent); }
.cs-prose blockquote {
    margin: 0 0 18px;
    padding: 14px 20px;
    border-left: 2px solid var(--cs-accent);
    background: rgba(79, 195, 176, .06);
    border-radius: 0 var(--cs-r-md) var(--cs-r-md) 0;
    color: var(--cs-text-item);
}
.cs-prose table { width: 100%; border-collapse: collapse; margin: 0 0 18px; font-size: 15px; }
.cs-prose th, .cs-prose td { padding: 10px 14px; border: 1px solid var(--cs-line); text-align: left; }
.cs-prose th { background: rgba(43, 59, 92, .45); color: var(--cs-white); font-weight: 700; }
.cs-prose code {
    font-family: var(--cs-mono);
    font-size: .9em;
    background: rgba(30, 43, 71, .9);
    border: 1px solid var(--cs-line);
    border-radius: var(--cs-r-xs);
    padding: 2px 6px;
    color: var(--cs-accent);
}
.cs-prose pre { background: #0B1322; border: 1px solid var(--cs-line); border-radius: var(--cs-r-md); padding: 18px; overflow-x: auto; }
.cs-prose pre code { background: none; border: 0; padding: 0; color: var(--cs-text-item); }
.cs-prose img { border-radius: var(--cs-r-md); border: 1px solid var(--cs-line); }

/* Prose у світлих секціях */
.cs-section--light .cs-prose, .cs-section--light-grad .cs-prose { color: var(--cs-light-body); font-size: 16px; }
.cs-section--light .cs-prose strong, .cs-section--light-grad .cs-prose strong,
.cs-section--light .cs-prose b, .cs-section--light-grad .cs-prose b { color: var(--cs-light-ink); }
.cs-section--light .cs-prose li::marker { color: var(--cs-light-accent); }
.cs-section--light .cs-prose blockquote { border-color: var(--cs-light-accent); background: rgba(47, 140, 124, .07); color: var(--cs-light-body); }
.cs-section--light .cs-prose th, .cs-section--light .cs-prose td,
.cs-section--light-grad .cs-prose th, .cs-section--light-grad .cs-prose td { border-color: var(--cs-light-line); }
.cs-section--light .cs-prose th, .cs-section--light-grad .cs-prose th { background: #EEF2F8; color: var(--cs-light-ink); }
.cs-section--light .cs-prose code, .cs-section--light-grad .cs-prose code { background: #EDF1F7; border-color: var(--cs-light-line); color: var(--cs-light-accent); }
.cs-section--light .cs-prose pre { background: #0E1728; }

/* ── Поява при скролі (керується JS) ── */
html.js [data-reveal] {
    opacity: 0;
    transform: translateY(16px);
    transition: opacity .42s ease-out, transform .42s ease-out;
}
html.js [data-reveal].is-revealed { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after { animation: none !important; transition: none !important; }
    html.js [data-reveal] { opacity: 1; transform: none; }
}

.skip-link {
    position: absolute;
    left: -9999px;
    top: 0;
    z-index: 300;
    background: var(--cs-accent);
    color: var(--cs-on-accent);
    padding: 10px 18px;
    font-weight: 700;
    border-radius: 0 0 var(--cs-r-sm) 0;
}
.skip-link:focus { left: 0; }