/* --- BIẾN DÙNG CHUNG TOÀN SITE --- */
:root {
    --bg-dark: #0d1117;
    --bg-card: #161b22;
    --primary: #a1ffce;
    --accent: #38bdf8;
    --text-main: #f0f6fc;
    --text-dim: #8b949e;
    --border: #30363d;
    --gradient: linear-gradient(90deg, #a1ffce 0%, #38bdf8 100%);
}

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

body {
    background-color: var(--bg-dark);
    color: var(--text-main);
    font-family: 'Inter', 'Segoe UI', sans-serif;
    line-height: 1.6;
}

/* Navbar dùng chung cho cả 3 trang */
.main-navbar {
    background: rgba(13, 17, 23, 0.9);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    padding: 12px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
}

.logo-area { display: flex; align-items: center; gap: 10px; text-decoration: none; }
.nav-logo { width: 40px; height: 40px; border-radius: 50%; border: 2px solid var(--primary); }
.logo-text { font-weight: 800; font-size: 1.3rem; background: var(--gradient); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }

.nav-menu { display: flex; gap: 15px; }
.nav-item { color: var(--text-dim); text-decoration: none; font-size: 0.9rem; padding: 8px 15px; border-radius: 8px; transition: 0.3s; }
.nav-item:hover, .nav-item.active { color: var(--primary); background: rgba(161, 255, 206, 0.1); }

/* Hero Section */
.hero { padding: 80px 20px; text-align: center; }
.main-title { 
    font-size: clamp(2.5rem, 8vw, 5rem); 
    font-weight: 800; 
    background: var(--gradient); 
    -webkit-background-clip: text; 
    -webkit-text-fill-color: transparent;
    letter-spacing: -2px;
}

/* Announcement Card */
.container { max-width: 800px; margin: 0 auto; padding: 20px; }
.announcement-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 24px;
    padding: 40px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.4);
}

.quote-box {
    margin-top: 25px;
    padding: 20px;
    background: rgba(255,255,255,0.03);
    border-left: 4px solid var(--accent);
    border-radius: 8px;
    font-style: italic;
}

.cta-button {
    display: inline-block;
    margin-top: 30px;
    padding: 15px 40px;
    background: var(--gradient);
    color: #000;
    font-weight: 800;
    border-radius: 12px;
    text-decoration: none;
    text-transform: uppercase;
    transition: 0.3s;
}

.cta-button:hover { transform: translateY(-3px); box-shadow: 0 10px 20px rgba(161, 255, 206, 0.3); }

/* Mobile Menu Toggle */
.menu-toggle { display: none; cursor: pointer; }
.bar { display: block; width: 25px; height: 3px; background: var(--primary); margin: 5px 0; transition: 0.3s; }

@media (max-width: 768px) {
    .menu-toggle { display: block; }
    .nav-menu {
        position: fixed; top: 65px; right: -100%; width: 250px; height: calc(100vh - 65px);
        background: var(--bg-card); flex-direction: column; padding: 20px; transition: 0.4s;
    }
    .nav-menu.active { right: 0; }
    .announcement-card { padding: 20px; }
}