/*
 XF Bootstrap — базовый набор стилей под стилистику XFormula.
 Не подключен автоматически. Импортируй выборочно при необходимости.
*/

:root {
    --xf-accent: #ff6b35;
    --xf-accent-2: #ff9051;
    --xf-bg: #0f0f0f;
    --xf-surface: #1a1a1a;
    --xf-text: #ffffff;
    --xf-muted: rgba(255, 255, 255, 0.72);
    --xf-border: rgba(255, 255, 255, 0.08);
    --xf-radius: 12px;
}

/* Layout */
body {
    margin: 0;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--xf-bg);
    color: var(--xf-text);
}

.xf-container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 clamp(16px, 3vw, 28px);
    box-sizing: border-box;
}

/* Header / Nav */
.xf-header {
    position: fixed;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: calc(100% - clamp(12px, 1.2vw, 24px));
    max-width: 1260px;
    height: 80px;
    background: linear-gradient(135deg, rgba(25,25,25,0.92), rgba(28,28,28,0.82));
    border: 1px solid var(--xf-border);
    border-radius: 0 0 clamp(16px, 2vw, 24px) clamp(16px, 2vw, 24px);
    box-shadow: 0 18px 48px rgba(0, 0, 0, 0.24);
    backdrop-filter: blur(10px);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: clamp(7px, 1vw, 12px) clamp(14px, 2vw, 24px);
    z-index: 1000;
    box-sizing: border-box;
}

.xf-logo {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    text-decoration: none;
    color: var(--xf-text);
    font-weight: 800;
    letter-spacing: 0.3px;
}

.xf-nav {
    display: flex;
    gap: clamp(6px, 1vw, 12px);
    align-items: center;
}

.xf-nav a {
    color: #fff;
    text-decoration: none;
    font-weight: 600;
    font-size: 13px;
    padding: 10px 14px;
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(255, 255, 255, 0.06);
    transition: all 0.2s ease;
}

.xf-nav a:hover {
    color: var(--xf-accent);
    border-color: rgba(255, 255, 255, 0.14);
    transform: translateY(-1px);
}

.xf-nav a.xf-active {
    background: rgba(255, 107, 53, 0.16);
    border-color: rgba(255, 107, 53, 0.35);
    box-shadow: 0 10px 28px rgba(255, 107, 53, 0.25);
    color: #ffb58a;
}

.xf-burger {
    display: none;
    flex-direction: column;
    gap: 6px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.xf-burger span {
    width: 28px;
    height: 3px;
    background: #fff;
    border-radius: 2px;
    transition: all 0.3s ease;
}

/* Buttons */
.xf-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 18px;
    border-radius: 12px;
    border: 1px solid transparent;
    font-weight: 700;
    text-decoration: none;
    color: #fff;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease, border-color 0.2s ease;
}

.xf-btn--primary {
    background: linear-gradient(135deg, var(--xf-accent), var(--xf-accent-2));
    box-shadow: 0 14px 30px rgba(255, 107, 53, 0.35);
}

.xf-btn--ghost {
    border: 1px solid rgba(255, 255, 255, 0.3);
    background: rgba(255, 255, 255, 0.08);
}

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

/* Cards */
.xf-card {
    background: #fff;
    color: #1f1f1f;
    border-radius: var(--xf-radius);
    padding: 18px 16px;
    border: 1px solid rgba(0,0,0,0.05);
    box-shadow: 0 14px 32px rgba(0,0,0,0.08);
}

/* Footer */
.xf-footer {
    padding: clamp(30px, 5vw, 60px) var(--section-pad-x, 24px);
    background: #0d0d0d;
    color: #b5b5b5;
}

.xf-footer__inner {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    align-items: center;
    justify-content: space-between;
}

.xf-footer__socials {
    display: flex;
    gap: 10px;
}

.xf-footer__socials a {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.08);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    text-decoration: none;
}

/* Responsive */
@media (max-width: 992px) {
    .xf-nav {
        display: none;
    }
    .xf-burger {
        display: flex;
    }
}