:root {
    --color-bg: #0f1419;
    --color-surface: #1a2029;
    --color-border: #2a3441;
    --color-accent: #4a9eff;
    --color-accent-soft: rgba(74, 158, 255, 0.1);
    --color-text: #e6edf3;
    --color-text-secondary: #8b949e;
    --color-text-muted: #6e7681;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --radius: 8px;
    --radius-lg: 12px;
    --max-width: 900px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--color-bg);
    color: var(--color-text);
    font-family: var(--font-family);
    line-height: 1.7;
    font-size: 16px;
}

/* Prevent scroll when mobile menu is open */
body.menu-open {
    overflow: hidden;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 2rem;
}

/* ── Navbar ── */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 2rem;
    background: rgba(15, 20, 25, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
}

.nav-brand {
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--color-accent);
    flex-shrink: 0;
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover {
    color: var(--color-text);
}

.lang-switcher {
    display: flex;
    gap: 0.25rem;
    flex-shrink: 0;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-shrink: 0;
}

.lang-btn {
    background: transparent;
    border: 1px solid var(--color-border);
    color: var(--color-text-muted);
    padding: 0.3rem 0.6rem;
    border-radius: 4px;
    font-size: 0.7rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    font-family: var(--font-family);
}

.lang-btn:hover {
    color: var(--color-text);
    border-color: var(--color-text-secondary);
}

.lang-btn.active {
    background: var(--color-accent);
    border-color: var(--color-accent);
    color: #fff;
}

/* ── Hamburger button ── */
.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 36px;
    height: 36px;
    background: transparent;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    cursor: pointer;
    padding: 7px;
    flex-shrink: 0;
    transition: border-color 0.2s;
}

.nav-toggle:hover {
    border-color: var(--color-text-secondary);
}

.nav-toggle span {
    display: block;
    height: 2px;
    width: 100%;
    background: var(--color-text-secondary);
    border-radius: 2px;
    transition: all 0.25s ease;
    transform-origin: center;
}

/* Animate to X when open */
.nav-toggle.open span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}
.nav-toggle.open span:nth-child(2) {
    opacity: 0;
    transform: scaleX(0);
}
.nav-toggle.open span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* ── Buttons ── */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.875rem;
    transition: all 0.2s;
}

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

.btn-primary:hover {
    background: #3d8de0;
    transform: translateY(-1px);
}

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

.btn-secondary:hover {
    border-color: var(--color-text-secondary);
    color: var(--color-text);
}

/* ── Page content container ── */
#page-content {
    padding-top: 4rem;
}

/* ── Animations ── */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ── Responsive: Navbar ── */
@media (max-width: 768px) {
    .navbar {
        padding: 0.875rem 1.25rem;
        gap: 0.75rem;
    }

    /* Show hamburger, hide desktop links */
    .nav-toggle {
        display: flex;
    }

    .nav-links {
        position: fixed;
        top: 57px;
        left: 0;
        right: 0;
        bottom: 0;
        background: var(--color-bg);
        flex-direction: column;
        align-items: center;
        justify-content: center;
        gap: 2.5rem;
        transform: translateX(100%);
        transition: transform 0.3s ease;
        z-index: 998;
        overflow-y: auto;
    }

    .nav-links.open {
        transform: translateX(0);
    }

    .nav-links a {
        font-size: 1.3rem;
        font-weight: 500;
        color: var(--color-text);
    }

    .container {
        padding: 0 1.25rem;
    }
}