/* === SECTION INTRO NÂNG CẤP === */
.course-intro {
    text-align: center;
    padding: 100px 20px 60px;
    background: linear-gradient(135deg, #ffffff 0%, #f8fcff 100%);
    position: relative;
    overflow: hidden;
}

.course-intro::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(0, 70, 88, 0.03) 0%, transparent 70%);
    border-radius: 50%;
    z-index: 0;
}

.course-intro h2 {
    font-size: 3.2rem;
    font-weight: 800;
    margin-bottom: 25px;
    color: #004658;
    position: relative;
    z-index: 1;
    background: linear-gradient(135deg, #004658, #00a8cc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.course-intro p {
    font-size: 1.2rem;
    color: #586e75;
    max-width: 800px;
    margin: 0 auto 40px;
    line-height: 1.8;
    position: relative;
    z-index: 1;
}

/* === COURSE CARDS NÂNG CẤP === */
.course-cards {
    display: flex;
    flex-wrap: wrap;
    gap: 35px;
    justify-content: center;
    padding: 60px 20px;
    max-width: 1400px;
    margin: 0 auto;
    position: relative;
}

.course-card {
    background: linear-gradient(135deg, #ffffff 0%, #f8fcff 100%);
    padding: 40px 30px;
    border-radius: 24px;
    box-shadow: 
        0 10px 30px rgba(0, 70, 88, 0.08),
        0 4px 12px rgba(0, 70, 88, 0.05);
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    width: 320px;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    position: relative;
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.8);
}

.course-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    border-radius: 24px;
    padding: 2px;
    background: linear-gradient(135deg, rgba(0, 70, 88, 0.1), rgba(0, 168, 204, 0.1));
    -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    -webkit-mask-composite: xor;
    mask-composite: exclude;
    pointer-events: none;
}

.course-card::after {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: linear-gradient(45deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transform: rotate(45deg);
    transition: all 0.6s ease;
    opacity: 0;
}

.course-card:hover {
    transform: translateY(-12px) scale(1.02);
    box-shadow: 
        0 20px 50px rgba(0, 70, 88, 0.15),
        0 8px 25px rgba(0, 70, 88, 0.1);
}

.course-card:hover::after {
    opacity: 1;
    animation: shine 1.5s ease;
}

@keyframes shine {
    0% { transform: rotate(45deg) translateX(-100%); }
    100% { transform: rotate(45deg) translateX(100%); }
}

.course-card h3 {
    margin: 0 0 20px 0;
    font-size: 1.5rem;
    color: #004658;
    font-weight: 700;
    line-height: 1.3;
    position: relative;
    z-index: 1;
}

.course-icon {
    width: 70px;
    height: 70px;
    background: linear-gradient(135deg, #004658, #00a8cc);
    border-radius: 18px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 25px;
    color: white;
    font-size: 1.8rem;
    box-shadow: 0 8px 20px rgba(0, 70, 88, 0.2);
    transition: all 0.3s ease;
}

.course-card:hover .course-icon {
    transform: scale(1.1) rotate(5deg);
}

.course-card p {
    font-size: 1rem;
    color: #586e75;
    margin: 15px 0 25px;
    line-height: 1.6;
    flex-grow: 1;
    position: relative;
    z-index: 1;
}

.course-features {
    list-style: none;
    padding: 0;
    margin: 20px 0;
    position: relative;
    z-index: 1;
}

.course-features li {
    padding: 8px 0;
    padding-left: 25px;
    position: relative;
    color: #555;
    font-size: 0.95rem;
}

.course-features li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: #00a8cc;
    font-weight: bold;
    font-size: 1.1em;
}

.course-card .btn-detail {
    padding: 14px 28px;
    background: linear-gradient(135deg, #004658, #00a8cc);
    color: #fff;
    font-weight: 600;
    border: none;
    border-radius: 16px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    position: relative;
    z-index: 1;
    box-shadow: 0 6px 20px rgba(0, 70, 88, 0.3);
    letter-spacing: 0.5px;
}

.course-card .btn-detail:hover {
    background: linear-gradient(135deg, #003a4e, #0097b8);
    transform: translateY(-3px);
    box-shadow: 0 10px 25px rgba(0, 70, 88, 0.4);
}

/* === MODAL NÂNG CẤP === */
.modal {
    display: none;
    position: fixed;
    z-index: 10000;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow-y: auto;
    background-color: rgba(0, 0, 0, 0.75);
    backdrop-filter: blur(5px);
    padding: 40px 20px;
    animation: fadeIn 0.4s ease;
}

.modal-content {
    background: linear-gradient(135deg, #ffffff 0%, #f8fcff 100%);
    margin: auto;
    padding: 50px 40px;
    border-radius: 28px;
    max-width: 1100px;
    position: relative;
    box-shadow: 
        0 25px 60px rgba(0, 0, 0, 0.2),
        0 10px 30px rgba(0, 0, 0, 0.1);
    animation: slideUp 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    border: 1px solid rgba(255, 255, 255, 0.9);
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px) scale(0.95);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.modal-content h3 {
    margin-top: 0;
    font-size: 2.2rem;
    font-weight: 700;
    color: #004658;
    margin-bottom: 15px;
    background: linear-gradient(135deg, #004658, #00a8cc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.modal-content p {
    margin: 15px 0 30px;
    font-size: 1.1rem;
    color: #586e75;
    line-height: 1.7;
}

.close {
    position: absolute;
    top: 25px;
    right: 30px;
    font-size: 32px;
    font-weight: 300;
    color: #888;
    cursor: pointer;
    transition: all 0.3s ease;
    width: 45px;
    height: 45px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.05);
}

.close:hover {
    color: #004658;
    background: rgba(0, 70, 88, 0.1);
    transform: rotate(90deg);
}

/* === TABLES NÂNG CẤP === */
.modal table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0;
    margin-top: 30px;
    font-size: 1rem;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 8px 25px rgba(0, 70, 88, 0.1);
}

.modal table th, .modal table td {
    border: none;
    padding: 18px 15px;
    text-align: center;
    word-wrap: break-word;
    transition: all 0.3s ease;
}

.modal table th {
    background: linear-gradient(135deg, #004658, #00a8cc);
    color: #fff;
    font-weight: 600;
    font-size: 1.05rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.modal table tbody tr {
    background: #fff;
}

.modal table tbody tr:nth-child(even) {
    background: #f8fcff;
}

.modal table tbody tr:hover {
    background: #f0f9ff;
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(0, 70, 88, 0.1);
}

.modal table tbody tr:hover td {
    color: #004658;
}

/* === H4 NÂNG CẤP === */
.modal h4 {
    margin-top: 40px;
    font-size: 1.3rem;
    font-weight: 700;
    color: #004658;
    padding-bottom: 10px;
    border-bottom: 3px solid #00a8cc;
    display: inline-block;
}

/* === RESPONSIVE NÂNG CẤP === */
@media (max-width: 1200px) {
    .course-cards {
        gap: 30px;
    }
    
    .course-card {
        width: 300px;
    }
}

@media (max-width: 1024px) {
    .modal-content {
        padding: 40px 30px;
        max-width: 90%;
    }
    
    .course-intro h2 {
        font-size: 2.8rem;
    }
}

@media (max-width: 768px) {
    .course-intro {
        padding: 80px 20px 50px;
    }
    
    .course-intro h2 {
        font-size: 2.3rem;
    }
    
    .course-intro p {
        font-size: 1.1rem;
    }
    
    .course-cards {
        flex-direction: column;
        align-items: center;
        gap: 25px;
        padding: 40px 20px;
    }
    
    .course-card {
        width: 90%;
        max-width: 400px;
        padding: 35px 25px;
    }
    
    .modal-content {
        padding: 35px 25px;
        margin: 20px auto;
    }
    
    .modal table {
        display: block;
        overflow-x: auto;
        white-space: nowrap;
        border-radius: 12px;
    }
    
    .modal table th, .modal table td {
        font-size: 0.9rem;
        padding: 15px 12px;
    }
    
    .modal-content h3 {
        font-size: 1.8rem;
    }
    
    .close {
        top: 15px;
        right: 20px;
        width: 40px;
        height: 40px;
        font-size: 28px;
    }
}

@media (max-width: 480px) {
    .course-intro h2 {
        font-size: 2rem;
    }
    
    .course-card {
        width: 95%;
        padding: 30px 20px;
    }
    
    .course-card h3 {
        font-size: 1.3rem;
    }
    
    .course-card p {
        font-size: 0.95rem;
    }
    
    .modal-content {
        padding: 30px 20px;
    }
    
    .modal-content h3 {
        font-size: 1.5rem;
    }
    
    .modal-content p {
        font-size: 1rem;
    }
    
    .modal table th, .modal table td {
        font-size: 0.85rem;
        padding: 12px 8px;
    }
    
    .course-icon {
        width: 60px;
        height: 60px;
        font-size: 1.5rem;
    }
}

/* === ANIMATION NÂNG CẤP === */
@keyframes fadeIn {
    from { 
        opacity: 0; 
        backdrop-filter: blur(0px);
    }
    to { 
        opacity: 1; 
        backdrop-filter: blur(5px);
    }
}

/* Hiệu ứng xuất hiện cho cards */
.course-card {
    opacity: 0;
    transform: translateY(30px);
    animation: cardAppear 0.6s ease forwards;
}

@keyframes cardAppear {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Delay cho từng card */
.course-card:nth-child(1) { animation-delay: 0.1s; }
.course-card:nth-child(2) { animation-delay: 0.2s; }
.course-card:nth-child(3) { animation-delay: 0.3s; }
.course-card:nth-child(4) { animation-delay: 0.4s; }
.course-card:nth-child(5) { animation-delay: 0.5s; }
.course-card:nth-child(6) { animation-delay: 0.6s; }

/* Scrollbar tùy chỉnh cho modal */
.modal::-webkit-scrollbar {
    width: 8px;
}

.modal::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.1);
}

.modal::-webkit-scrollbar-thumb {
    background: linear-gradient(135deg, #004658, #00a8cc);
    border-radius: 4px;
}

.modal::-webkit-scrollbar-thumb:hover {
    background: linear-gradient(135deg, #003a4e, #0097b8);
}