/* ================= common style ================= */
:root {
    --bg-dark: #0a0a0a;
    --card-bg: #1a1a1a;
    --text-primary: #f0f0f0;
    --accent-blue: #6cb3eb;
    --accent-green: #7de893;
    --accent-orange: #ffa94d;
    --border-radius: 16px;
    --card-shadow: 0 9px 32px rgba(0, 0, 0, 0.3);
}

a { color: lightskyblue; }
a:visited { color: #6d4b8d; }
a:hover { color: #ffffff; }
a:active { color: #ff4040; text-decoration:none; font-weight:normal; }

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


/* bg */
.site-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    background-image: url('/assets/images/homepage_bg.webp');
    background-size: cover;
    background-position: center;
    filter: brightness(0.4);
}

/* ================= navbar style ================= */
.navbar {
    background: rgba(0, 0, 0, 0.95);
    padding: 0.8rem 0;
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    backdrop-filter: blur(8px);
    box-shadow: 0 2px 15px rgba(0, 0, 0, 0.3);
}

.nav-container {
    max-width: 100%;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 100px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.nav-container::-webkit-scrollbar {
    height: 3px;
}

.nav-container::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.3);
    border-radius: 3px;
}

.nav-logo {
    height: 60px;
    width: auto;
    transition: transform 0.3s ease;
    border-radius: 4px;
    flex-shrink: 0;
}

.logo:hover .nav-logo {
    transform: scale(1.05);
    filter: brightness(1.1);
}

.nav-links {
    display: flex;
    gap: 1.2rem;
    list-style: none;
    padding-bottom: 10px;
    margin: 0;
    flex-shrink: 0;
    white-space: nowrap;
}

a.nav-link {
    color: white;
    text-decoration: none;
    padding: 0.4rem 0.8rem;
    border-radius: 4px;
    transition: all 0.3s;
    font-size: 0.95rem;
    display: inline-block;
    position: relative;
}

a.nav-link:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateY(-1px);
}

.active {
    border-bottom: 2px solid #00b4d8;
}

/* ================= main content style ================= */
.main-content {
    max-width: 1200px;
    margin: 100px auto 80px;
    padding: 2rem;
    color: white;
    position: relative;
    backdrop-filter: blur(12px);
    border-radius: 12px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
    background: fixed;
    line-height: 1.7;
}

.hero {
    text-align: center;
    padding: 4rem 2rem;
    margin: -2rem -2rem 4rem;
    position: relative;
    overflow: hidden;
    background: linear-gradient(45deg, 
        rgba(0, 180, 216, 0.15) 0%, 
        rgba(15, 15, 15, 0) 60%);
}

.hero h1 {
    font-size: 3.5rem;
    letter-spacing: -0.03em;
    margin: 0;
    background: linear-gradient(135deg, #e0e0e0 30%, #00b4d8);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    animation: textReveal 1.5s ease-out;
    position: relative;
    padding-bottom: 1.2rem;
}

.hero::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 150%;
    height: 150%;
    background: radial-gradient(circle, 
        rgba(0, 180, 216, 0.15) 0%, 
        rgba(0, 0, 0, 0) 70%);
    transform: translate(-50%, -50%);
    z-index: 0;
}

.hero h1::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80% !important;
    max-width: 1000px;
    height: 2px;
    background: #00b4d8;
    border-radius: 2px;
    box-shadow: 0 2px 8px rgba(0, 180, 216, 0.3);
    animation: lineExpand 0.8s ease-out forwards;
}

@keyframes lineExpand {
    from {
        width: 0;
        opacity: 0;
    }
    to {
        width: 80%;
        opacity: 1;
    }
}

.additional-content {
    column-count: 1;
    column-gap: 3rem;
    animation: fadeInUp 1s ease;
}

.additional-content p {
    position: relative;
    padding-left: 1.5rem;
    break-inside: avoid;
    margin-bottom: 1.2rem;
}
/*
.additional-content li::before {
    content: "✓";
    color: #00b4d8;
    position: absolute;
    left: 0;
    font-weight: 700;
    text-shadow: 0 0 8px rgba(0, 180, 216, 0.3);
}*/

@media (max-width: 768px) {
    .navbar {
        padding: 0.6rem 0;
    }
    
    .nav-container {
        padding: 0 15px;
        gap: 1.5rem;
    }
    
    .nav-logo {
        height: 50px;
    }
    
    .nav-link {
        font-size: 0.85rem;
        padding: 0.4rem 0.6rem;
    }

    .hero h1 {
        font-size: 2.5rem;
        line-height: 1.2;
        padding-bottom: 1rem;
    }
    
    .additional-content {
        column-count: 1;
    }
    
    .hero::after {
        width: 200%;
        height: 200%;
    }
    
    .main-content {
        margin: 80px 15px 40px;
        padding: 1.5rem;
    }
    .hero h1::after {
        height: 1.5px;
        max-width: 1000px;
        animation: lineExpand 0.8s ease-out forwards;
    }
}

@keyframes textReveal {
    from { opacity: 0; transform: translateY(1.5rem); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(2rem); }
    to { opacity: 1; transform: translateY(0); }
}