/* ============================================================
   PROMETHEUS RESEARCH GROUP — Main Stylesheet
   Colors: Red (primary), White (secondary), Black (authority)
   Mobile-first. No frameworks. Clean.
   ============================================================ */

/* --- Reset & Base --- */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --red: #C41E3A;
    --red-dark: #8B0000;
    --red-light: #E8384F;
    --white: #FFFFFF;
    --off-white: #F8F8F8;
    --black: #111111;
    --gray-dark: #333333;
    --gray-mid: #666666;
    --gray-light: #CCCCCC;
    --gray-border: #E0E0E0;

    --font-main: 'Segoe UI', -apple-system, BlinkMacSystemFont, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'Courier New', Courier, monospace;

    --header-height: 60px;
    --transition-speed: 0.35s;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-main);
    color: var(--black);
    background: var(--white);
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    color: var(--red);
    text-decoration: none;
    transition: color var(--transition-speed);
}

a:hover, a:focus {
    color: var(--red-dark);
    text-decoration: underline;
}

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

/* --- Header --- */
#site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: var(--header-height);
    background: var(--white);
    border-bottom: 2px solid var(--red);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 16px;
}

.header-brand {
    display: flex;
    align-items: center;
    gap: 10px;
}

.header-flame {
    width: 28px;
    height: 28px;
    background: var(--red);
    border-radius: 50% 50% 50% 0;
    transform: rotate(-45deg);
    flex-shrink: 0;
}

.header-title {
    font-size: 14px;
    font-weight: 700;
    color: var(--red);
    letter-spacing: 1.5px;
    line-height: 1.2;
}

.header-tagline {
    font-size: 10px;
    color: var(--gray-mid);
    letter-spacing: 0.5px;
    line-height: 1.2;
    display: none;
}

/* --- Hamburger Menu Toggle --- */
.menu-toggle {
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
    display: flex;
    flex-direction: column;
    gap: 5px;
    z-index: 1001;
}

.menu-bar {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--red);
    transition: transform var(--transition-speed), opacity var(--transition-speed);
}

.menu-toggle.open .menu-bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.menu-toggle.open .menu-bar:nth-child(2) {
    opacity: 0;
}

.menu-toggle.open .menu-bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* --- Mobile Menu Overlay --- */
.mobile-menu {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 999;
    background: rgba(255, 255, 255, 0.97);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-speed);
}

.mobile-menu.open {
    opacity: 1;
    pointer-events: auto;
}

.menu-list {
    list-style: none;
    text-align: center;
}

.menu-list li {
    margin: 8px 0;
}

.menu-link {
    font-size: 18px;
    font-weight: 600;
    color: var(--black);
    letter-spacing: 1px;
    padding: 8px 16px;
    display: inline-block;
    transition: color var(--transition-speed);
}

.menu-link:hover, .menu-link:focus {
    color: var(--red);
    text-decoration: none;
}

/* --- Footer --- */
#site-footer {
    background: var(--black);
    color: var(--gray-light);
    padding: 20px 16px;
    text-align: center;
    font-size: 13px;
}

.footer-inner {
    max-width: 800px;
    margin: 0 auto;
}

.footer-links {
    margin-top: 8px;
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
}

.footer-links a {
    color: var(--gray-light);
    font-size: 12px;
}

.footer-links a:hover {
    color: var(--white);
}

/* --- Utility --- */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}

/* --- Desktop Breakpoint --- */
@media (min-width: 768px) {
    .header-title {
        font-size: 18px;
    }

    .header-tagline {
        display: block;
    }

    .menu-link {
        font-size: 16px;
    }
}

@media (min-width: 1024px) {
    #site-header {
        padding: 0 32px;
    }

    .header-title {
        font-size: 20px;
        letter-spacing: 2px;
    }

    .header-tagline {
        font-size: 11px;
    }
}