/* =========================================
   CSS Base & Variables
   ========================================= */
:root {
    --primary-color: #cd1627;
    --primary-dark: #b0101f;
    --text-dark: #0f172a;
    --text-gray: #6b7280;
    --bg-light: #f8fafc;
    --white: #ffffff;
    --border-color: #e5e7eb;
    --blue: #1a73e8;
    --red: #cd1627;
    --green: #0f9d58;
    --yellow: #f6c343;
    --dark-bg: #1a1110;
    --grid-beige: #fffdf9;
    --font-family: 'Inter', system-ui, -apple-system, sans-serif;
    --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);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: var(--font-family);
    color: var(--text-dark);
    background-color: var(--white);
    line-height: 1.6;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.text-primary, .text-red { color: var(--red); }
.text-yellow { color: var(--yellow); }
.text-blue { color: var(--blue); }
.text-green { color: var(--green); }

.bg-white { background-color: var(--white); }

.font-bold { font-weight: 700; }
.font-black { font-weight: 900; }

/* =========================================
   Buttons
   ========================================= */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 8px 24px;
    border-radius: 9999px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: var(--transition);
    gap: 8px;
}

.btn-lg {
    padding: 12px 32px;
    font-size: 16px;
}

.btn-login {
    background-color: #000;
    color: var(--white);
}

.btn-login:hover {
    background-color: #333;
}

.btn-register {
    background-color: var(--white);
    color: #000;
    border: 1px solid #d1d5db;
}

.btn-register:hover {
    border-color: #000;
}

.btn-white {
    background-color: var(--white);
    color: var(--text-dark);
    border: 1px solid transparent;
}
.btn-white:hover {
    background-color: #f1f5f9;
}

.btn-outline-dark {
    background-color: transparent;
    color: var(--text-dark);
    border: 1px solid var(--text-dark);
}
.btn-outline-dark:hover {
    background-color: var(--text-dark);
    color: var(--white);
}

/* =========================================
   Header
   ========================================= */
.header {
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.header-container {
    height: 72px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 48px;
}

.logo-text {
    font-size: 26px;
    letter-spacing: -1px;
}

.nav-menu {
    display: flex;
    gap: 32px;
}

.nav-link {
    font-size: 14px;
    color: var(--text-gray);
    font-weight: 500;
}

.nav-link:hover {
    color: var(--text-dark);
}

.auth-buttons {
    display: flex;
    gap: 12px;
}

/* =========================================
   Hero Section
   ========================================= */
.hero-section {
    position: relative;
    padding: 80px 0 120px;
    background-color: var(--white);
    text-align: center;
    overflow: hidden;
}

/* Left & Right red triangles in Hero */
.hero-bg-left {
    position: absolute;
    left: -150px;
    top: 35%;
    transform: translateY(-50%);
    width: 500px;
    height: 500px;
    background: linear-gradient(to right, var(--red) 20%, transparent 100%);
    clip-path: polygon(0 0, 100% 50%, 0 100%);
    opacity: 0.9;
    display: flex;
    align-items: center;
    justify-content: flex-start;
    padding-left: 170px;
    transition: left 0.5s ease-in-out;
}
.hero-bg-left.retracted {
    left: -400px;
}
.hero-bg-left::after {
    content: 'DOLEARN';
    color: rgba(255, 255, 255, 0.4);
    font-size: 40px;
    font-weight: 900;
    transform: rotate(-25deg);
}

.hero-bg-right {
    position: absolute;
    right: -150px;
    top: 35%;
    transform: translateY(-50%);
    width: 500px;
    height: 500px;
    background: linear-gradient(to left, var(--red) 20%, transparent 100%);
    clip-path: polygon(100% 0, 0 50%, 100% 100%);
    opacity: 0.9;
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding-right: 170px;
    transition: right 0.5s ease-in-out;
}
.hero-bg-right.retracted {
    right: -400px;
}
.hero-bg-right::after {
    content: 'DOLEARN';
    color: rgba(255, 255, 255, 0.4);
    font-size: 40px;
    font-weight: 900;
    transform: rotate(25deg);
}

.hero-text-area {
    position: relative;
    z-index: 10;
    max-width: 800px;
    margin: 0 auto;
}

.hero-subtitle {
    font-size: 14px;
    color: var(--text-gray);
    margin-bottom: 16px;
}

.hero-title {
    font-size: 40px;
    font-weight: 800;
    color: var(--text-dark);
    margin-bottom: 40px;
}

.hero-stats {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 40px;
    margin-bottom: 80px;
}

.stat-item {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.stat-top, .stat-bottom {
    font-size: 10px;
    color: #9ca3af;
    text-transform: uppercase;
    font-weight: 600;
    letter-spacing: 0.5px;
}

.stat-main {
    font-size: 24px;
    font-weight: 800;
    color: var(--text-dark);
}

.stat-divider {
    width: 1px;
    height: 40px;
    background-color: var(--border-color);
}

/* Teachers Carousel */
.teachers-area {
    position: relative;
    z-index: 10;
    max-width: 900px;
    margin: 0 auto;
}

.teachers-title-wrap {
    margin-bottom: 40px;
    position: relative;
    display: inline-block;
}

.teachers-tag {
    background-color: var(--red);
    color: var(--white);
    font-size: 10px;
    font-weight: 700;
    padding: 4px 12px;
    border-radius: 4px;
    position: absolute;
    top: -12px;
    left: 20px;
    text-transform: uppercase;
}

.teachers-title {
    font-size: 24px;
    font-weight: 800;
    border: 2px solid var(--red);
    padding: 12px 24px;
    display: inline-block;
    color: var(--text-dark);
}

.teachers-carousel {
    display: flex;
    align-items: center;
    gap: 20px;
}

.teachers-list {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    flex: 1;
}

.carousel-btn {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--white);
    border: 1px solid var(--border-color);
    color: var(--text-gray);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    display: flex;
    align-items: center;
    justify-content: center;
}
.carousel-btn:hover {
    color: var(--text-dark);
    border-color: var(--text-dark);
}

.teacher-card {
    position: relative;
    padding-bottom: 20px;
}

.teacher-frame {
    border: 1px dashed var(--red);
    padding: 10px;
    position: relative;
    background: #fffafa; /* very light red tint */
}
.teacher-frame::before, .teacher-frame::after {
    content: '';
    position: absolute;
    width: 6px;
    height: 6px;
    background: var(--red);
    border-radius: 50%;
}
.teacher-frame::before { top: -3px; left: -3px; }
.teacher-frame::after { top: -3px; right: -3px; }

.teacher-frame img {
    width: 100%;
    aspect-ratio: 3/4;
    object-fit: cover;
    display: block;
}

.teacher-name {
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    background: var(--red);
    color: var(--white);
    font-size: 11px;
    font-weight: 700;
    padding: 6px 12px;
    white-space: nowrap;
}

/* =========================================
   Hall of Fame (Red grid)
   ========================================= */
.fame-section {
    background-color: var(--red);
    background-image: 
        linear-gradient(rgba(255,255,255,0.15) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,0.15) 1px, transparent 1px);
    background-size: 40px 40px;
    position: relative;
    padding: 80px 0;
    color: var(--white);
    border-top-left-radius: 60px;
    border-top-right-radius: 60px;
    margin-top: -60px;
    z-index: 10;
}

.fame-bottom-curve {
    position: absolute;
    bottom: -40px; /* pull down into next section */
    left: 0;
    right: 0;
    height: 80px;
    background-color: var(--red);
    background-image: 
        linear-gradient(rgba(255,255,255,0.15) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,0.15) 1px, transparent 1px);
    background-size: 40px 40px;
    border-bottom-left-radius: 60px;
    border-bottom-right-radius: 60px;
    z-index: 10;
}

.fame-container {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 60px;
    align-items: center;
}

.fame-title-wrap {
    margin-bottom: 24px;
}

.fame-title-top {
    font-size: 32px;
    font-weight: 900;
    display: block;
}

.fame-title-bottom {
    font-size: 42px;
    font-weight: 900;
    background-color: var(--yellow);
    color: var(--text-dark);
    display: inline-block;
    padding: 4px 16px;
    border-radius: 8px;
    transform: rotate(-2deg);
    margin-top: 4px;
}

.fame-desc {
    font-size: 16px;
    line-height: 1.6;
    margin-bottom: 32px;
    opacity: 0.9;
}

.student-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
}

.student-card {
    background: var(--white);
    border-radius: 12px;
    padding: 12px;
    color: var(--text-dark);
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
    display: flex;
    flex-direction: column;
}

.student-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 8px;
    margin-bottom: 12px;
}

.exam-logo {
    height: 18px;
    object-fit: contain;
}

.logo-text-small {
    font-size: 12px;
    font-weight: 900;
    letter-spacing: -0.5px;
}

.student-photo {
    height: 120px;
    background-color: #f1f5f9;
    border-radius: 8px;
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 40px;
    color: #cbd5e1;
}

.student-info {
    text-align: center;
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.student-rank {
    font-size: 10px;
    color: var(--red);
    font-weight: 800;
    margin-bottom: 4px;
}

.student-name {
    font-size: 13px;
    font-weight: 600;
}

/* =========================================
   Courses Section
   ========================================= */
.courses-section {
    background-color: var(--grid-beige);
    background-image: 
        linear-gradient(rgba(0,0,0,0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0,0,0,0.03) 1px, transparent 1px);
    background-size: 40px 40px;
    padding: 80px 0;
    border-top-left-radius: 60px;
    border-top-right-radius: 60px;
    margin-top: -60px;
    position: relative;
    z-index: 11;
}

.courses-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    margin-bottom: 60px;
}

.courses-main-title {
    font-size: 36px;
    font-weight: 900;
    margin-bottom: 16px;
}

.bg-red-tag {
    background-color: var(--red);
    color: var(--white);
    padding: 4px 16px;
    border-radius: 8px;
    display: inline-block;
    border: 2px solid #000;
    box-shadow: 3px 3px 0 #000;
}

.courses-desc {
    color: var(--text-gray);
    font-size: 15px;
}

.course-category {
    margin-bottom: 60px;
}
.mt-50 { margin-top: 50px; }

.category-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.category-title {
    font-size: 14px;
    font-weight: 700;
}
.category-title.round {
    border-radius: 999px;
}

.bg-green-tag {
    background-color: var(--green);
    color: var(--white);
    padding: 6px 16px;
    display: inline-block;
    border: 2px solid #000;
    box-shadow: 3px 3px 0 #000;
}

.category-nav {
    display: flex;
    align-items: center;
    gap: 16px;
}

.view-all {
    font-size: 13px;
    font-weight: 600;
    text-decoration: underline;
}

.nav-btn {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    border: 1px solid var(--text-dark);
    background: transparent;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}

.courses-carousel {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.course-card {
    background: var(--white);
    border-radius: 16px;
    overflow: hidden;
    border: 2px solid #000;
    box-shadow: 4px 4px 0 #000;
    transition: var(--transition);
}

.course-card:hover {
    box-shadow: 6px 6px 0 #000;
    transform: translateY(-4px);
}

.course-img {
    padding: 16px;
}

.course-placeholder {
    height: 160px;
    border-radius: 12px;
    background-color: #f1f5f9;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 16px;
    border: 1px solid var(--border-color);
}
.bg-light-green {
    background-color: #e6f4ea;
    border-color: #ceead6;
}

.course-badge {
    font-size: 12px;
    font-weight: 800;
}

.course-info {
    padding: 20px;
    border-top: 2px solid transparent;
}
.border-red { border-top-color: var(--red); }
.border-green { border-top-color: var(--green); }

.course-name {
    font-size: 15px;
    font-weight: 700;
    margin-bottom: 12px;
    height: 44px;
}

.course-teacher {
    font-size: 13px;
    color: var(--text-gray);
}

/* =========================================
   Info Section (Tìm hiểu kỳ thi)
   ========================================= */
.info-section {
    background-color: var(--yellow);
    background-image: 
        linear-gradient(rgba(0,0,0,0.05) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0,0,0,0.05) 1px, transparent 1px);
    background-size: 40px 40px;
    padding: 80px 0;
    border-top-left-radius: 60px;
    border-top-right-radius: 60px;
    margin-top: -60px; /* pull up to overlap with courses section */
    position: relative;
    z-index: 12;
}

.info-header {
    margin-bottom: 60px;
}

.info-title {
    font-size: 36px;
    font-weight: 900;
    margin-bottom: 16px;
    color: var(--text-dark);
}

.bg-white-tag {
    background-color: var(--white);
    padding: 4px 16px;
    border-radius: 8px;
    display: inline-block;
    border: 2px solid #000;
    box-shadow: 3px 3px 0 #000;
}

.info-desc {
    color: rgba(0,0,0,0.7);
    font-size: 15px;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.info-card {
    background: var(--white);
    border-radius: 16px;
    padding: 24px;
    border: 2px solid #000;
    box-shadow: 4px 4px 0 #000;
    transition: var(--transition);
}

.info-card:hover {
    box-shadow: 6px 6px 0 #000;
    transform: translateY(-4px);
}

.info-card:hover .info-card-title {
    color: var(--red);
}

.info-badge {
    display: inline-block;
    border: 1px solid var(--text-dark);
    font-size: 10px;
    font-weight: 700;
    padding: 4px 12px;
    border-radius: 999px;
    margin-bottom: 16px;
}

.info-card-title {
    font-size: 16px;
    font-weight: 800;
    margin-bottom: 12px;
    line-height: 1.4;
    transition: var(--transition);
}

.info-card-desc {
    font-size: 13px;
    color: var(--text-gray);
    margin-bottom: 20px;
    line-height: 1.6;
}

.info-link {
    font-size: 13px;
    font-weight: 700;
    color: var(--red);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

/* =========================================
   Footer
   ========================================= */
.footer {
    background-color: var(--dark-bg);
    color: var(--white);
    padding: 80px 0 30px;
    position: relative;
    overflow: hidden;
}

.footer-bg-left {
    position: absolute;
    left: 0;
    bottom: 0;
    width: 250px;
    height: 250px;
    background: linear-gradient(135deg, var(--red) 0%, var(--primary-dark) 100%);
    clip-path: polygon(0 100%, 0 0, 100% 100%);
    opacity: 0.8;
}

.footer-bg-right {
    position: absolute;
    right: 0;
    bottom: 0;
    width: 300px;
    height: 300px;
    background: linear-gradient(225deg, var(--red) 0%, var(--dark-bg) 100%);
    clip-path: polygon(100% 100%, 100% 0, 0 100%);
}

.footer-container {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    position: relative;
    z-index: 10;
    margin-bottom: 40px;
}

.logo-group {
    margin-bottom: 12px;
}

.logo-text-large {
    font-size: 40px;
    font-weight: 900;
    letter-spacing: -1.5px;
    line-height: 1;
}

.brand-subtitle {
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.5px;
    margin-bottom: 24px;
}

.contact-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.contact-list li {
    font-size: 13px;
    color: #cbd5e1;
    display: flex;
    align-items: flex-start;
    gap: 12px;
}

.contact-list i {
    margin-top: 4px;
}

.footer-col h4 {
    font-size: 14px;
    font-weight: 700;
    margin-bottom: 24px;
    text-transform: uppercase;
}

.footer-col ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.footer-col ul li, .footer-col ul li a {
    font-size: 13px;
    color: #cbd5e1;
}

.footer-col ul li a:hover {
    color: var(--white);
    text-decoration: underline;
}

.footer-bottom {
    position: relative;
    z-index: 10;
    font-size: 12px;
    color: #64748b;
    border-top: 1px solid rgba(255,255,255,0.1);
    padding-top: 24px;
}

/* =========================================
   Responsive
   ========================================= */
@media (max-width: 1024px) {
    .fame-container { grid-template-columns: 1fr; }
    .student-grid { grid-template-columns: repeat(2, 1fr); }
    .courses-carousel { grid-template-columns: repeat(2, 1fr); }
    .info-grid { grid-template-columns: repeat(2, 1fr); }
    .footer-container { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
    .nav-menu, .btn-login, .btn-register { display: none; }
    .hero-title { font-size: 28px; }
    .hero-stats { flex-direction: column; gap: 20px; }
    .stat-divider { width: 100%; height: 1px; }
    .teachers-list { grid-template-columns: repeat(2, 1fr); }
    .student-grid { grid-template-columns: 1fr; }
    .courses-carousel { grid-template-columns: 1fr; }
    .info-grid { grid-template-columns: 1fr; }
    .footer-container { grid-template-columns: 1fr; }
}

/* =========================================
   Typewriter Animation
   ========================================= */
.typewriter-cursor {
    animation: blink 0.7s step-end infinite;
    font-weight: 300;
}

@keyframes blink {
    from, to { opacity: 1; }
    50% { opacity: 0; }
}

.blink-text {
    animation: blink 1s step-end infinite;
}

.fade-in-text {
    opacity: 0;
    animation: fadeInText 2s ease-in forwards;
}

@keyframes fadeInText {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.fade-in-out-text {
    animation: fadeInOut 3s ease-in-out infinite;
}

@keyframes fadeInOut {
    0%, 100% { opacity: 0; }
    50% { opacity: 1; }
}

/* =========================================
   Floating Contact Menu
   ========================================= */
.floating-contact {
    position: fixed;
    right: 20px;
    bottom: 20px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    z-index: 9999;
}

.contact-icon {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 18px;
    text-decoration: none;
    border: 2px solid white;
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.contact-icon:hover {
    transform: scale(1.1);
    box-shadow: 0 6px 12px rgba(0,0,0,0.3);
    color: white;
}

.contact-icon.zalo {
    background-color: #0068ff;
}
.contact-icon.zalo .zalo-text {
    font-size: 12px;
    font-weight: 800;
}

.contact-icon.messenger {
    background: linear-gradient(45deg, #0695FF, #A334FA, #FF6968);
}

.contact-icon.facebook {
    background-color: #1877f2;
}

.contact-icon.phone {
    background-color: #dc2626;
}