/* ==========================================================================
   S.E.A - BASE STYLES & VARIABLES
   ========================================================================== */
:root {
    --primary-color: #E11D2E; /* Red accent S.E.A */
    --primary-hover: #C81928;
    --text-main: #111827; /* Dark navy text */
    --text-muted: #4B5563;
    --bg-light: #F9FAFB; /* Light grey */
    --bg-white: #FFFFFF;
    --border-color: #E5E7EB;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    color: var(--text-main);
    line-height: 1.6;
    background-color: var(--bg-white);
}

a {
    text-decoration: none;
    color: inherit;
    transition: color 0.3s ease;
}

ul {
    list-style: none;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.text-accent { color: var(--primary-color); }
.text-center { text-align: center; }
.bg-light { background-color: var(--bg-light); }
.bg-white { background-color: var(--bg-white); }
.mt-16 { margin-top: 16px; }
.mt-32 { margin-top: 32px; }

/* ==========================================================================
   BUTTONS
   ========================================================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    border-radius: 8px;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
}

.btn-outline {
    background-color: transparent;
    border-color: var(--text-main);
    color: var(--text-main);
}

.btn-outline:hover {
    background-color: var(--text-main);
    color: var(--bg-white);
}

.btn-sm { padding: 8px 16px; font-size: 0.875rem; }
.btn-full { width: 100%; }

/* ==========================================================================
   HEADER & NAVIGATION
   ========================================================================== */
.site-header {
    position: sticky;
    top: 0;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border-color);
    z-index: 100;
}

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

.brand-logo {
    display: flex;
    align-items: center; /* Căn giữa theo chiều dọc */
    text-decoration: none; /* Xóa gạch chân liên kết */
}

.brand-logo img {
    height: 75px; /* Đặt chiều cao tinh tế cho biểu trưng trên máy tính */
    width: auto; /* Duy trì tỷ lệ khung hình */
    display: block; /* Tránh khoảng cách lạ bên dưới hình ảnh */
}

/* Đảm bảo căn chỉnh và kích thước hợp lý trên thiết bị di động */
@media (max-width: 768px) {
    .brand-logo img {
        height: 40px; /* Giảm kích thước trên mobile để bố cục gọn gàng */
    }
}

.logo-secondary {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 500;
}

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

.desktop-nav a {
    font-weight: 500;
    color: var(--text-main);
}

.desktop-nav a:hover {
    color: var(--primary-color);
}

/* Mobile Menu */
.hamburger {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.hamburger-line {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--text-main);
    margin: 5px 0;
    transition: 0.3s;
}

.mobile-nav {
    position: absolute;
    top: 72px;
    left: 0;
    width: 100%;
    background: var(--bg-white);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-md);
    
    /* Hiệu ứng trượt mượt mà */
    opacity: 0;
    visibility: hidden;
    transform: translateY(-15px);
    transition: all 0.3s ease-in-out;
    z-index: 99;
}

.mobile-nav.is-open { 
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

/* Hiệu ứng biến 3 gạch thành dấu X khi bấm */
.hamburger.is-active .hamburger-line:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}
.hamburger.is-active .hamburger-line:nth-child(2) {
    opacity: 0;
}
.hamburger.is-active .hamburger-line:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

.mobile-nav ul {
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.mobile-nav a {
    font-weight: 500;
    display: block;
    padding: 8px 0;
}

/* ==========================================================================
   HERO SECTION (LEFT CONTENT)
   ========================================================================== */
.hero {
    padding: 80px 0;
    overflow: hidden;
}

.hero-inner {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    align-items: center;
}

.hero-content .badge {
    display: inline-block;
    padding: 6px 12px;
    background-color: #FFF1F2;
    color: var(--primary-color);
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 20px;
}

.hero-content h1 {
    font-size: 3rem;
    line-height: 1.2;
    margin-bottom: 20px;
    color: var(--text-main);
}

.hero-promise {
    font-size: 1.125rem;
    color: var(--text-muted);
    margin-bottom: 32px;
}

.hero-cta-group {
    display: flex;
    gap: 16px;
    margin-bottom: 32px;
}

.trust-strip {
    display: flex;
    gap: 24px;
    flex-wrap: wrap;
}

.trust-item {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
}

/* ==========================================================================
   PREMIUM HERO VISUAL (RIGHT CONTENT - SẾP VỪA DUYỆT)
   ========================================================================== */
.hero-visual-premium {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 560px;
}

.premium-visual-stage {
    position: relative;
    width: 620px;
    height: 560px;
}

.visual-glow {
    position: absolute;
    inset: 50% auto auto 50%;
    width: 460px;
    height: 460px;
    transform: translate(-50%, -50%);
    border-radius: 50%;
    background: radial-gradient(circle, rgba(225, 29, 46, 0.08), rgba(225, 29, 46, 0.02) 45%, transparent 70%);
    filter: blur(2px);
    z-index: 0;
}

.main-photo-card {
    position: absolute;
    left: 50%;
    top: 50%;
    width: 330px;
    height: 380px;
    transform: translate(-50%, -50%) rotate(-2deg);
    border-radius: 36px;
    overflow: hidden;
    border: 8px solid #ffffff;
    box-shadow: 0 34px 90px rgba(17, 24, 39, 0.18);
    z-index: 4;
}

.main-photo-card img { width: 100%; height: 100%; object-fit: cover; }

.floating-photo {
    position: absolute;
    width: 150px;
    height: 120px;
    border-radius: 28px;
    overflow: hidden;
    border: 6px solid #ffffff;
    box-shadow: 0 24px 60px rgba(17, 24, 39, 0.15);
    z-index: 3;
    animation: floatSoft 6s ease-in-out infinite;
}

.floating-photo img { width: 100%; height: 100%; object-fit: cover; }

.photo-1 { left: 20px; top: 80px; --rotate: -14deg; transform: rotate(var(--rotate)); animation-delay: 0s; }
.photo-2 { right: 8px; top: 72px; --rotate: 12deg; transform: rotate(var(--rotate)); animation-delay: 1s; }
.photo-3 { left: 0; bottom: 70px; --rotate: 10deg; transform: rotate(var(--rotate)); animation-delay: 1.8s; }
.photo-4 { right: 34px; bottom: 54px; --rotate: -12deg; transform: rotate(var(--rotate)); animation-delay: 2.6s; }

.floating-badge {
    position: absolute;
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 16px;
    background: rgba(255, 255, 255, 0.92);
    border: 1px solid rgba(229, 231, 235, 0.9);
    border-radius: 16px;
    box-shadow: 0 18px 45px rgba(17, 24, 39, 0.12);
    backdrop-filter: blur(10px);
    z-index: 6;
    white-space: nowrap;
}

.floating-badge strong { display: block; font-size: 0.92rem; color: var(--text-main); line-height: 1.2; }
.floating-badge small { display: block; margin-top: 2px; font-size: 0.76rem; color: var(--text-muted); line-height: 1.2; }

.badge-icon { display: flex; align-items: center; justify-content: center; width: 34px; height: 34px; border-radius: 50%; font-size: 1rem; }
.badge-score .badge-icon { background-color: #FFF1F2; }
.badge-speaking .badge-icon { background-color: #F0F9FF; }
.badge-progress .badge-icon { background-color: #F0FDF4; }

.badge-score { left: 56px; top: 190px; }
.badge-speaking { right: 0; top: 300px; }
.badge-progress { left: 150px; bottom: 24px; }

@keyframes floatSoft {
    0%, 100% { transform: translateY(0) rotate(var(--rotate)); }
    50% { transform: translateY(-14px) rotate(var(--rotate)); }
}

@media (prefers-reduced-motion: reduce) { .floating-photo { animation: none; } }

/* ==========================================================================
   OTHER SECTIONS (CREDIBILITY, COURSES, METHOD, TESTIMONIALS)
   ========================================================================== */
.section-padding { padding: 80px 0; }
.section-header { margin-bottom: 48px; }
.section-header h2 { font-size: 2.5rem; margin-bottom: 16px; }

/* Credibility Banner */
.credibility-banner { border-top: 1px solid var(--border-color); border-bottom: 1px solid var(--border-color); padding: 40px 0; }
.credibility-inner { display: flex; justify-content: space-between; text-align: center; }
.cred-title { display: block; font-size: 1.25rem; font-weight: 700; color: var(--primary-color); margin-bottom: 8px; }
.cred-desc { color: var(--text-muted); }

/* Courses */
.course-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 30px; }
.course-card { background: var(--bg-white); padding: 32px; border-radius: 16px; box-shadow: var(--shadow-md); display: flex; flex-direction: column; position: relative; border: 1px solid var(--border-color); }
.course-card.recommended { border: 2px solid var(--primary-color); transform: translateY(-10px); }
.course-tag { font-size: 0.875rem; color: var(--text-muted); font-weight: 600; text-transform: uppercase; letter-spacing: 1px; margin-bottom: 12px; display: block; }
.recommended-badge { position: absolute; top: -14px; left: 50%; transform: translateX(-50%); background: var(--primary-color); color: white; padding: 4px 16px; border-radius: 20px; font-size: 0.875rem; font-weight: 600; }
.course-card h3 { font-size: 1.5rem; margin-bottom: 16px; }
.course-outcome { color: var(--text-muted); margin-bottom: 24px; min-height: 72px; }
.course-features { margin-bottom: 32px; flex-grow: 1; }
.course-features li { padding-left: 24px; position: relative; margin-bottom: 12px; color: var(--text-main); }
.course-features li::before { content: '✓'; position: absolute; left: 0; color: var(--primary-color); font-weight: bold; }

/* Method */
.method-inner { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; }
.method-content h2 { font-size: 2.5rem; margin-bottom: 20px; }
.timeline-step { display: flex; gap: 20px; margin-bottom: 32px; }
.step-number { width: 40px; height: 40px; background: var(--primary-color); color: white; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-weight: 700; flex-shrink: 0; }
.step-text h4 { font-size: 1.25rem; margin-bottom: 8px; }
.step-text p { color: var(--text-muted); }

/* Testimonials */
.testi-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 30px; }
.testi-card { background: var(--bg-white); padding: 32px; border-radius: 16px; box-shadow: var(--shadow-md); border: 1px solid var(--border-color); }
.context-tag { display: inline-block; background: var(--bg-light); padding: 4px 12px; border-radius: 4px; font-size: 0.75rem; color: var(--text-muted); margin-right: 8px; margin-bottom: 16px; }
.testi-quote { font-style: italic; margin-bottom: 24px; color: var(--text-main); min-height: 90px; }
.testi-author { display: flex; align-items: center; gap: 16px; }
.author-avatar { width: 50px; height: 50px; border-radius: 50%; background: #E5E7EB; }
.author-info strong { display: block; color: var(--primary-color); }
.author-info span { font-size: 0.875rem; color: var(--text-muted); }

/* Contact Form */
.contact-inner { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; }
.contact-copy h2 { font-size: 2.5rem; margin-bottom: 20px; }
.contact-form-wrapper { padding: 40px; border-radius: 16px; }
.form-group { margin-bottom: 20px; }
.form-group label { display: block; font-weight: 600; margin-bottom: 8px; }
.required { color: var(--primary-color); }
.form-group input, .form-group select { width: 100%; padding: 12px 16px; border: 1px solid var(--border-color); border-radius: 8px; font-family: inherit; font-size: 1rem; }
.form-group input:focus, .form-group select:focus { outline: none; border-color: var(--primary-color); }
.error-msg { color: var(--primary-color); font-size: 0.875rem; display: none; margin-top: 4px; }
.privacy-note { font-size: 0.875rem; color: var(--text-muted); text-align: center; margin-top: 16px; }
.link-red { color: var(--primary-color); font-weight: 600; }
.box-shadow-soft { box-shadow: var(--shadow-lg); }
.success-icon { font-size: 3rem; color: #10B981; margin-bottom: 16px; }

/* ==========================================================================
   FOOTER
   ========================================================================== */
.site-footer { background-color: var(--text-main); color: #D1D5DB; padding: 60px 0 20px; }
.footer-inner { display: grid; grid-template-columns: 1fr 2fr; gap: 60px; margin-bottom: 40px; }
.footer-logo { font-size: 2rem; font-weight: 700; color: white; display: block; }
.footer-brand p { color: #9CA3AF; }
.footer-links h4 { color: white; margin-bottom: 20px; font-size: 1.125rem; }
.campus-list { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.campus-list li { margin-bottom: 16px; line-height: 1.6; }
.campus-list a { color: var(--primary-color); font-weight: 600; }
.footer-bottom { border-top: 1px solid #374151; padding-top: 20px; display: flex; justify-content: space-between; font-size: 0.875rem; color: #9CA3AF; }
.policy-links a { margin-left: 16px; }
.policy-links a:hover { color: white; }

/* ==========================================================================
   RESPONSIVE DESIGN
   ========================================================================== */
@media (max-width: 1024px) {
    .hero-inner, .method-inner, .contact-inner { grid-template-columns: 1fr; gap: 40px; }
    .hero-content { text-align: center; }
    .hero-cta-group { justify-content: center; }
    .trust-strip { justify-content: center; }
    .course-grid, .testi-grid { grid-template-columns: repeat(2, 1fr); }
    
    /* Hero Visual Premium Resize */
    .premium-visual-stage { width: 500px; height: 500px; }
    .main-photo-card { width: 280px; height: 330px; }
    .floating-photo { width: 128px; height: 100px; }
    .photo-1 { left: 10px; top: 70px; }
    .photo-2 { right: 0; top: 70px; }
    .photo-3 { left: 4px; bottom: 82px; }
    .photo-4 { right: 20px; bottom: 72px; }
    .badge-score { left: 32px; top: 185px; }
    .badge-speaking { right: -10px; top: 290px; }
    .badge-progress { left: 110px; bottom: 30px; }
}

@media (max-width: 768px) {
    .desktop-nav, .hidden-mobile { display: none; }
    .hamburger { display: block; }
    .hero-content h1 { font-size: 2.25rem; }
    .credibility-inner { flex-direction: column; gap: 24px; }
    .course-grid, .testi-grid { grid-template-columns: 1fr; }
    .course-card.recommended { transform: translateY(0); margin-top: 20px; }
    .footer-inner, .campus-list { grid-template-columns: 1fr; gap: 30px; }
    .footer-bottom { flex-direction: column; text-align: center; gap: 16px; }
    
    /* Hero Visual Premium Resize Mobile */
    .hero-visual-premium { min-height: 420px; margin-top: 30px; }
    .premium-visual-stage { width: 340px; height: 400px; }
    .visual-glow { width: 320px; height: 320px; }
    .main-photo-card { width: 230px; height: 270px; border-radius: 28px; border-width: 6px; }
    .floating-photo { width: 94px; height: 76px; border-radius: 20px; border-width: 4px; }
    .photo-1 { left: -2px; top: 60px; }
    .photo-2 { right: -2px; top: 58px; }
    .photo-3 { left: 8px; bottom: 70px; }
    .photo-4 { right: 10px; bottom: 64px; }
    .floating-badge { padding: 9px 12px; border-radius: 12px; }
    .floating-badge strong { font-size: 0.78rem; }
    .floating-badge small { display: none; }
    .badge-icon { width: 28px; height: 28px; font-size: 0.86rem; }
    .badge-score { left: 28px; top: 170px; }
    .badge-speaking { right: 22px; top: 250px; }
    .badge-progress { display: none; }
}

@media (max-width: 480px) {
    .hero-cta-group { flex-direction: column; }
    
    /* Hero Visual Premium Extra Small */
    .premium-visual-stage { width: 300px; height: 360px; }
    .main-photo-card { width: 210px; height: 250px; }
    .floating-photo { width: 82px; height: 66px; }
    .photo-3, .photo-4 { display: none; }
    .badge-score { left: 12px; top: 150px; }
    .badge-speaking { right: 8px; top: 230px; }
}

/* ==========================================================================
   PROMO BANNER CAMPAIGN (NO CLOSE BUTTON)
   ========================================================================== */
.promo-banner {
    background-color: #E8EFEB;
    border-bottom: 1px solid var(--border-color);
    padding: 12px 0;
    position: relative;
    display: block;
    z-index: 99;
}

.promo-inner {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    position: relative;
}

.promo-image {
    position: relative;
    width: 60px;
    height: 48px;
    flex-shrink: 0;
    border-radius: 6px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    display: none;
}

@media (min-width: 768px) {
    .promo-image { display: block; }
}

.promo-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.promo-badge {
    position: absolute;
    top: -4px;
    right: -4px;
    background-color: var(--primary-color);
    color: white;
    font-size: 0.6rem;
    font-weight: bold;
    padding: 2px 6px;
    border-radius: 12px;
    z-index: 2;
}

.promo-content {
    flex-grow: 1;
    max-width: 800px;
    animation: gentleDrift 4s ease-in-out infinite; 
}

@keyframes gentleDrift {
    0%, 100% { transform: translateX(0); }
    50% { transform: translateX(8px); }
}

.promo-title {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--text-main);
    margin-bottom: 2px;
}

.promo-desc {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 4px;
}

.promo-desc strong {
    color: var(--text-main);
}

.promo-link {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--primary-color);
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.promo-link:hover {
    text-decoration: underline;
}

@media (max-width: 768px) {
    .promo-inner {
        flex-direction: column;
        text-align: center;
        gap: 8px;
        padding: 0 10px; /* Đã chỉnh lại cân đều 2 bên vì không còn nút X */
    }
    
    .promo-content {
        animation: gentleDriftMobile 4s ease-in-out infinite;
    }

    .promo-title { font-size: 0.9rem; }
    .promo-desc { font-size: 0.8rem; }
}

@keyframes gentleDriftMobile {
    0%, 100% { transform: translateX(0); }
    50% { transform: translateX(4px); }
}