/* --- Cài đặt chung & Font chữ --- */
:root {
    --primary-color: #2ecc71; /* Màu xanh lá cây cho header */
    --glow-color: rgba(46, 204, 113, 0.7);
    --text-color: #ecf0f1;
    --dark-bg: #000000;
    --border-color: rgba(46, 204, 113, 0.3);
}

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

body {
    font-family: 'Roboto', sans-serif;
    background-color: var(--dark-bg);
    color: var(--text-color);
    line-height: 1.6;
    overflow-x: hidden;
}

/* --- Hiệu ứng nền Canvas --- */
#brain-particles-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
}

/* --- Header --- */
#main-header {
    background-color: var(--primary-color);
    color: white;
    padding: 0 1rem;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    height: 60px;
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    transition: height 0.3s ease;
}

#main-header.scrolled {
    height: 50px;
}

#main-header h1 {
    font-size: 1rem;
    font-weight: normal;
}

/* --- Nội dung chính --- */
main {
    padding-top: 80px; /* Khoảng trống cho header */
    padding-bottom: 2rem;
}

.logo-container {
    text-align: center;
    margin-bottom: 2rem;
}

.logo-container img {
    max-width: 568px;
    width: 90%;
    height: auto;
}
.logo-container p {
    max-width: 800px;
    margin: 1rem auto 0;
    padding: 0 1rem;
    opacity: 0.9;
}


/* --- Cấu trúc Layout mới --- */
.content-wrapper {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
    padding: 0 1rem;
}


/* --- Hiệu ứng viền sáng (Giữ nguyên) --- */
.glowing-border {
    position: relative;
    padding: 2px; /* Độ dày của viền sáng */
    border-radius: 8px;
    overflow: hidden;
    background: transparent;
    width: 100%;
    max-width: 900px; /* Giới hạn chiều rộng chung */
}

.glowing-border::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: conic-gradient(
        transparent,
        var(--glow-color),
        transparent 20%
    );
    animation: rotate 4s linear infinite;
    z-index: 1;
}

.inner-content {
    background: rgba(10, 10, 10, 0.85); 
    backdrop-filter: blur(8px);
    border-radius: 6px; 
    padding: 2rem;
    position: relative;
    z-index: 2;
    border: 1px solid rgba(255, 255, 255, 0.1); 
}

@keyframes rotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}


/* --- Dropdown Menu chọn danh mục --- */
.category-selector .inner-content {
    padding: 1rem 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.category-selector label {
    font-size: 0.9rem;
    opacity: 0.8;
}

#program-select {
    width: 100%;
    padding: 0.8rem;
    background: rgba(0, 0, 0, 0.5);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    color: var(--text-color);
    font-size: 1rem;
    cursor: pointer;
}
#program-select:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* --- Nội dung Landing Page --- */
#landing-page-content .inner-content {
    display: flex;
    flex-direction: column;
    gap: 2.5rem; /* Khoảng cách giữa các khối nội dung */
}

.content-block h3 {
    color: var(--primary-color);
    margin-bottom: 0.75rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
    display: inline-block;
}

.content-block p {
    margin-bottom: 0.5rem;
}

.content-block ul {
    list-style: none;
    padding-left: 0;
}

.content-block ul li {
    padding-left: 1.5rem;
    position: relative;
    margin-bottom: 0.5rem;
}

.content-block ul li::before {
    content: '✓';
    color: var(--primary-color);
    position: absolute;
    left: 0;
    top: 0;
    font-weight: bold;
}

.headline {
    font-size: 2.2rem;
    font-weight: bold;
    text-align: center;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.short-description {
    text-align: center;
    font-size: 1.1rem;
    opacity: 0.9;
    max-width: 700px;
    margin: 0 auto;
}

.cta-section {
    text-align: center;
    background: rgba(0, 0, 0, 0.3);
    padding: 1.5rem;
    border-radius: 6px;
    margin-top: 1rem;
}

.cta-button {
    display: inline-block;
    margin-top: 1rem;
    padding: 0.8rem 2.5rem;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 1.1rem;
    cursor: pointer;
    text-decoration: none;
    transition: background-color 0.3s ease, transform 0.2s ease;
}

.cta-button:hover {
    background-color: #27ae60;
    transform: scale(1.05);
}


/* --- Hiệu ứng cuộn trang --- */
.fade-in-section {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

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


/* --- Footer (Giữ nguyên) --- */
footer {
    text-align: center;
    padding: 2rem 1rem;
    margin-top: 2rem;
    border-top: 1px solid var(--border-color);
    font-size: 0.9rem;
    opacity: 0.7;
}

/* --- Responsive Design --- */
@media (max-width: 768px) {
    .headline {
        font-size: 1.8rem;
    }
    .short-description {
        font-size: 1rem;
    }
    .inner-content {
        padding: 1.5rem;
    }
}

@media (max-width: 500px) {
    #main-header h1 {
        font-size: 0.8rem;
    }
    .headline {
        font-size: 1.5rem;
    }
}