/* Main CSS for CHINH.EDU.VN 
   Optimized for Laptop 14" & Mobile 
   Version: 1.3
*/

:root {
    --primary: #0d6efd;
    --primary-hover: #0a58ca;
    --dark: #1e293b;
    --muted: #64748b;
    --light-bg: #f8fafc;
    --border: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    /* Màu xanh thương hiệu - đậm đà và tin cậy hơn */
    --primary-tech: #0061ff; 
    --primary-dark: #0046b8;
    /* Hiệu ứng đổ bóng đổ sâu (Soft UI) */
    --shadow-button: 0 4px 14px 0 rgba(0, 97, 255, 0.39);
    --shadow-button-hover: 0 6px 20px rgba(0, 118, 255, 0.23);
}

body {
    font-family: 'Inter', sans-serif;
    color: var(--dark);
    background-color: #fff;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}
.btn-primary.btn-lg {
    background: linear-gradient(135deg, var(--primary-tech) 0%, #00a1ff 100%);
    border: none;
    font-weight: 600;
    letter-spacing: 0.5px;
    padding: 14px 35px;
    box-shadow: var(--shadow-button);
    transition: all 0.3s ease;
}

.btn-primary.btn-lg:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-button-hover);
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary-tech) 100%);
}

/* --- NAVIGATION --- */
.navbar {
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    padding: 0.6rem 0;
    z-index: 11 !important;
}

.navbar-brand span {
    letter-spacing: -0.5px;
}

.nav-link {
    font-size: 0.95rem;
    font-weight: 500;
    transition: var(--transition);
}

.active-custom {
    color: var(--primary) !important;
    font-weight: 700 !important;
}

/* --- HERO SECTION --- */
.hero-section {
    padding: 80px 0 !important;
}

.hero-section h1 {
    font-size: clamp(2rem, 5vw, 3.2rem);
    letter-spacing: -1px;
}

/* --- COURSE CARDS --- */
.course-card {
    transition: var(--transition);
    border: 1px solid rgba(0,0,0,0.05) !important;
    border-radius: 16px !important;
    overflow: hidden;
    background: #fff;
}

.course-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 25px -5px rgb(0 0 0 / 0.1) !important;
}

.course-card .card-img-top {
    transition: transform 0.6s ease;
}

.course-card:hover .card-img-top {
    transform: scale(1.08);
}

.course-card h6 {
    line-height: 1.5;
    font-size: 1rem;
    height: 48px; /* Giữ tiêu đề 2 dòng đều nhau */
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

/* Badge giá tiền nổi bật */
.course-card .text-danger.fw-bold {
    color: #ef4444 !important; /* Màu đỏ hiện đại hơn */
    font-size: 1.1rem;
}

/* Hiệu ứng nút "Học ngay" nhỏ */
.course-card .btn-primary {
    background: var(--primary-tech);
    border: none;
    font-size: 0.85rem;
    padding: 6px 15px;
}

/* --- TESTIMONIALS --- */
.testimonial-card {
    border-radius: 12px;
    border-left: 4px solid var(--primary) !important;
    transition: var(--transition);
}

.testimonial-card:hover {
    background-color: #f1f5f9 !important;
}





/* --- FOOTER --- */
footer {
    background: #0f172a;
    color: #94a3b8;
    border-top: 1px solid #1e293b;
}

footer h5, footer h6 {
    color: #fff;
}

footer a {
    color: #94a3b8;
    text-decoration: none;
    transition: var(--transition);
}

footer a:hover {
    color: #fff;
}

.social-icons a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 38px;
    height: 38px;
    background: #1e293b;
    border-radius: 50%;
    color: #fff;
    margin-right: 8px;
    transition: var(--transition);
}

/* --- 2. BREADCRUMB --- */
.breadcrumb {
    font-size: 0.9rem;
}
.breadcrumb-item a {
    color: var(--text-muted);
    transition: var(--transition);
}
.breadcrumb-item a:hover {
    color: var(--primary-color);
}

/* --- 3. NỘI DUNG CHI TIẾT (BÊN TRÁI) --- */
h1 {
    font-size: clamp(1.5rem, 3vw, 2.5rem);
    line-height: 1.2;
}

.course-description {
    font-size: 1.05rem;
    line-height: 1.8;
}

/* Accordion Nội dung khóa học */
.accordion-item {
    border: 1px solid #e2e8f0 !important;
    margin-bottom: 10px;
    border-radius: 12px !important;
}

.accordion-button {
    padding: 1.25rem;
    font-size: 1rem;
    border-radius: 12px !important;
}

.accordion-button:not(.collapsed) {
    color: var(--primary-color);
    background-color: var(--bg-light);
    box-shadow: none;
}

.accordion-button::after {
    background-size: 1rem;
}

/* List bài học */
.list-group-item {
    border-color: #f1f5f9 !important;
    transition: var(--transition);
}

.list-group-item:hover {
    background-color: var(--bg-light) !important;
    padding-left: 2rem !important;
}

.list-group-item i.bi-play-circle {
    font-size: 1.1rem;
    transition: var(--transition);
}

.list-group-item:hover i.bi-play-circle {
    transform: scale(1.2);
}

/* Badge Học thử */
.badge.bg-success-subtle {
    font-weight: 600;
    letter-spacing: 0.3px;
    padding: 6px 12px;
}

/* --- 4. SIDEBAR THANH TOÁN (BÊN PHẢI) --- */
.sticky-top {
    z-index: 10;
}

.card.shadow-lg {
    border: 1px solid rgba(0,0,0,0.05) !important;
    transition: var(--transition);
}

.card-img-top {
    transition: transform 0.5s ease;
}

.card.shadow-lg:hover .card-img-top {
    transform: scale(1.05);
}

/* Nút Vào học/Đăng ký */
.btn-lg {
    padding: 15px 25px;
    font-size: 1.1rem;
    transition: var(--transition);
}

.btn-success {
    background: linear-gradient(135deg, #198754 0%, #157347 100%);
    border: none;
}

.btn-success:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(25, 135, 84, 0.3) !important;
}

/* --- 5. TỐI ƯU MOBILE & LAPTOP 14" --- */

/* Mobile (< 768px) */
@media (max-width: 767.98px) {
    .row.g-5 {
        --bs-gutter-y: 2rem;
    }
    
    .col-lg-4 {
        order: -1; /* Đưa box giá tiền lên trên tiêu đề ở mobile */
        z-index: 1;
    }
    
    .sticky-top {
        position: relative !important;
        top: 0 !important;
    }

    .p-4.p-md-5 {
        padding: 1.5rem !important;
    }
    
    .list-group-item {
        padding: 1rem !important;
    }
    
    .badge {
        font-size: 0.7rem;
    }
}

/* Laptop 14" (Tầm 1366px - 1440px) */
@media (min-width: 992px) and (max-width: 1440px) {
    .container {
        max-width: 95%;
    }
    
    .col-lg-8 {
        width: 65%;
    }
    
    .col-lg-4 {
        width: 35%;
    }
}

/* Hiệu ứng "Làm sạch" nội dung editor */
.course-description img {
    max-width: 100%;
    height: auto;
    border-radius: 12px;
    margin: 20px 0;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
}

.social-icons a:hover {
    background: var(--primary);
    transform: translateY(-3px);
}

/* --- RESPONSIVE OPTIMIZATION --- */

/* Mobile (< 768px) */
@media (max-width: 767.98px) {
    /* Thu gọn Header */
    .navbar .container {
        display: flex;
        justify-content: space-between;
        align-items: center;
    }
    
    /* Ẩn các menu phụ khi chưa mở hamburger */
    .navbar-collapse {
        background: #fff;
        padding: 20px;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        box-shadow: 0 10px 15px rgba(0,0,0,0.1);
    }

    /* Tối ưu Hero Section */
    .hero-section {
        padding: 30px 15px !important; /* Thu nhỏ vùng xám */
        background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%) !important;
    }
    
    .hero-section h1 {
        font-size: 1.6rem !important;
        line-height: 1.3;
    }

    .hero-section p {
        font-size: 0.95rem;
        margin-bottom: 20px !important;
    }

    /* Tối ưu Card khóa học */
    .course-card {
        margin-bottom: 20px;
    }
    
    .course-card .card-img-top {
        height: 240px !important;
        border-radius: 12px 12px 0 0; /* Bo góc ảnh theo card */
    }

    .course-card .card-body {
        padding: 15px !important;
    }
}

@media (max-width: 991px) {
    .navbar > .container {
        display: flex;
        flex-wrap: nowrap !important; /* Ép không xuống dòng */
        align-items: center;
        justify-content: space-between;
    }
    
    .navbar-brand {
        margin-right: 0;
        font-size: 1.1rem; /* Thu nhỏ logo 1 chút trên mobile */
    }
    
    /* Thu gọn khoảng cách các mục menu khi mở ra */
    .navbar-nav .nav-link {
        padding: 5px 8px !important;
        border-bottom: 1px solid #f1f5f9;
    }
}

/* Laptop 14" (1366px - 1440px) */
@media (min-width: 992px) and (max-width: 1440px) {
    .container {
        max-width: 95% !important;
    }
    
    .course-card h6 {
        font-size: 0.9rem;
    }
}

/* --- UTILITIES --- */
.rounded-pill { border-radius: 50rem !important; }
.shadow-sm { box-shadow: var(--shadow-sm) !important; }