/* ==========================================================================
   DESIGN SYSTEM & CUSTOM VARIABLES
   ========================================================================== */
:root {
    /* Colors */
    --primary: #14b8a6;           /* Sky Blue y khoa */
    --primary-hover: #0369a1;
    --primary-light: #e0f2fe;
    --secondary: #14b8a6;         /* Teal xanh ngọc */
    --secondary-hover: #0f766e;
    --secondary-light: #ccfbf1;
    --accent: #f97316;            /* Orange CTA */
    --accent-hover: #ea580c;
    --accent-light: #ffedd5;
    --dark: #0f172a;              /* Slate 900 */
    --text-dark: #334155;         /* Slate 700 */
    --text-muted: #64748b;        /* Slate 500 */
    --bg-light: #f8fafc;          /* Slate 50 */
    --bg-card: #ffffff;
    --border-color: #e2e8f0;      /* Slate 200 */
    --warning: #ef4444;           /* Red */
    --warning-bg: #fef2f2;        /* Light Red */
    --warning-border: #fca5a5;
	
    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    
    /* Transitions */
    --transition-fast: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* Layout Constants */
    --header-height: 80px;
    --max-width: 1200px;
    --border-radius-sm: 8px;
    --border-radius-md: 12px;
    --border-radius-lg: 20px;
    
    /* Shadow */
    --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, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.03);
    --shadow-premium: 0 20px 25px -5px rgba(2, 132, 199, 0.08), 0 10px 10px -5px rgba(2, 132, 199, 0.04);
}

/* ==========================================================================
   RESET & BASE STYLES
   ========================================================================== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px; /* Base size */
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-sans);
    font-size: 1.0625rem; /* 17px - Dành cho người lớn tuổi dễ đọc */
    line-height: 1.65;
    color: var(--text-dark);
    background-color: var(--bg-light);
    overflow-x: hidden;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

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

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

h1, h2, h3, h4 {
    color: var(--dark);
    font-weight: 700;
    line-height: 1.25;
    margin-bottom: 0.5em;
}

ul {
    list-style-type: none;
}

/* Utility classes */
.container {
    width: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

.text-center { text-align: center; }
.max-w-700 { max-width: 700px; margin-left: auto; margin-right: auto; }
.mt-40 { margin-top: 40px; }
.w-full { width: 100%; }
.text-danger { color: var(--warning); }
.bg-teal-light { background-color: var(--secondary-light); }
.bg-blue-light { background-color: var(--primary-light); }
.text-teal { color: var(--secondary); }
.text-blue { color: var(--primary); }

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-sans);
    font-weight: 600;
    font-size: 1rem;
    padding: 12px 28px;
    border-radius: var(--border-radius-sm);
    border: none;
    cursor: pointer;
    transition: var(--transition-normal);
    box-shadow: var(--shadow-sm);
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: var(--primary);
    color: #fff;
    border: 2px solid var(--primary);
}

.btn-secondary:hover {
    background-color: var(--primary-light);
    transform: translateY(-2px);
}

.btn-cta {
    font-size: 1.125rem;
    padding: 16px 36px;
    border-radius: var(--border-radius-md);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    box-shadow: var(--shadow-md);
}

.btn-orange {
    background-color: var(--accent);
    color: white;
}

.btn-orange:hover {
    background-color: var(--accent-hover);
    color: white;
    transform: translateY(-3px);
    box-shadow: 0 10px 20px -5px rgba(234, 88, 12, 0.4);
}

.btn-teal {
    background-color: var(--secondary);
    color: white;
}

.btn-teal:hover {
    background-color: var(--secondary-hover);
    color: white;
    transform: translateY(-3px);
    box-shadow: 0 10px 20px -5px rgba(20, 184, 166, 0.4);
}

/* Badges */
.section-tag {
    display: inline-block;
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--primary);
    text-transform: uppercase;
    letter-spacing: 1px;
    background-color: var(--primary-light);
    padding: 6px 16px;
    border-radius: 100px;
    margin-bottom: 16px;
}

.section-tag.tag-warning {
    color: var(--warning);
    background-color: var(--warning-bg);
}

/* Back to Top */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: var(--primary);
    color: white;
    border: none;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg);
    z-index: 999;
    transition: var(--transition-normal);
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background-color: var(--primary-hover);
    transform: translateY(-3px);
}

.back-to-top svg {
    width: 20px;
    height: 20px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.625rem;
    font-weight: 800;
    color: var(--dark);
    letter-spacing: -0.5px;
}

.logo-img {
    height: 65px;
    width: auto;
    object-fit: contain;
}

/* ==========================================================================
   SECTION HEADER
   ========================================================================== */
.section-header {
    margin-bottom: 50px;
}

.section-title {
    font-size: 2.25rem;
    font-weight: 800;
    letter-spacing: -0.5px;
    color: var(--dark);
}

.section-subtitle {
    font-size: 1.1875rem;
    color: var(--text-muted);
    margin-top: 12px;
}

/* ==========================================================================
   SECTION 1: STICKY HEADER
   ========================================================================== */
.sticky-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--header-height);
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: var(--transition-normal);
}

.sticky-header.scrolled {
    height: 70px;
    box-shadow: var(--shadow-md);
}

.header-container {
    height: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-size: 1.625rem;
    font-weight: 800;
    color: var(--dark);
    letter-spacing: -0.5px;
}

.logo-accent {
    color: #62c9d1;
}

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

.nav-link {
    color: var(--text-dark);
    font-weight: 600;
    font-size: 0.9375rem;
    padding: 8px 0;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary);
    transition: var(--transition-normal);
}

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

.nav-link:hover::after {
    width: 100%;
}

.nav-link.active {
    color: var(--primary);
}

.nav-link.active::after {
    width: 100%;
}

.header-cta-group {
    display: flex;
    align-items: center;
    gap: 16px;
}

/* Hamburger menu */
.hamburger {
    display: none;
    flex-direction: column;
    justify-content: space-between;
    width: 30px;
    height: 21px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0;
}

.hamburger .bar {
    width: 100%;
    height: 3px;
    background-color: var(--dark);
    border-radius: 2px;
    transition: var(--transition-normal);
}

/* ==========================================================================
   SECTION 2: HERO BANNER
   ========================================================================== */
.hero-section {
    position: relative;
    padding-top: calc(var(--header-height) + 60px);
    padding-bottom: 80px;
    background: radial-gradient(circle at 75% 30%, rgba(2, 132, 199, 0.06) 0%, rgba(255, 255, 255, 0) 60%), linear-gradient(180deg, #f0f9ff 0%, #f8fafc 100%);
    overflow: hidden;
}

.hero-container {
    display: grid;
    grid-template-columns: 1.1fr 0.9fr;
    gap: 48px;
    align-items: center;
}

.badge-container {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 24px;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    font-size: 0.8125rem;
    font-weight: 700;
    padding: 6px 14px;
    border-radius: 100px;
    box-shadow: var(--shadow-sm);
}

.badge-medical {
    background-color: var(--primary-light);
    color: var(--primary-hover);
    border: 1px solid rgba(2, 132, 199, 0.15);
}

.badge-icon {
    margin-right: 6px;
}

.badge-suit {
    background-color: var(--secondary-light);
    color: var(--secondary-hover);
    border: 1px solid rgba(20, 184, 166, 0.15);
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 900;
    line-height: 1.15;
    letter-spacing: -1.5px;
    color: var(--dark);
    margin-bottom: 16px;
}

.hero-subtitle {
    font-size: 1.375rem;
    font-weight: 600;
    line-height: 1.45;
    color: var(--primary-hover);
    margin-bottom: 20px;
}

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

.hero-features-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-bottom: 40px;
}

.hero-feat-item {
    display: flex;
    align-items: center;
    font-weight: 600;
    color: var(--dark);
}

.feat-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 22px;
    height: 22px;
    background-color: var(--secondary);
    color: white;
    border-radius: 50%;
    font-size: 0.75rem;
    margin-right: 12px;
}

.hero-cta-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
}

.cta-svg {
    width: 20px;
    height: 20px;
    margin-right: 8px;
}

.hero-image-wrapper {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}

.hero-img-box {
    position: relative;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-premium);
    background-color: white;
    border: 8px solid white;
}

.hero-img {
    transition: var(--transition-slow);
    width: 100%;
    height: auto;
}

.hero-img-box:hover .hero-img {
    transform: scale(1.03);
}

.img-badge {
    position: absolute;
    bottom: 24px;
    left: 24px;
    background: rgba(15, 23, 42, 0.85);
    backdrop-filter: blur(8px);
    color: white;
    padding: 14px 20px;
    border-radius: var(--border-radius-md);
    display: flex;
    flex-direction: column;
    border-left: 4px solid var(--secondary);
    box-shadow: var(--shadow-lg);
}

.badge-text-bold {
    font-weight: 700;
    font-size: 1.125rem;
}

.badge-text-sub {
    font-size: 0.875rem;
    opacity: 0.8;
}

/* ==========================================================================
   SECTION 3: WARNING SECTION
   ========================================================================== */
.warning-section {
    padding: 80px 0;
    background-color: white;
}

.warning-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
    margin-top: 50px;
}

.warning-card {
    background-color: var(--bg-light);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 36px 28px;
    transition: var(--transition-normal);
    border-top: 4px solid var(--border-color);
}

.warning-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-top-color: var(--warning);
}

.warn-icon-wrapper {
    width: 50px;
    height: 50px;
    background-color: var(--warning-bg);
    color: var(--warning);
    border-radius: var(--border-radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 24px;
}

.warn-svg {
    width: 28px;
    height: 28px;
}

.warn-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 12px;
}

.warn-desc {
    font-size: 0.9375rem;
    color: var(--text-muted);
    line-height: 1.6;
}

.warning-footer {
    margin-top: 50px;
}

.warning-footer-text {
    font-size: 1.1875rem;
    color: var(--dark);
    margin-bottom: 24px;
}

/* ==========================================================================
   SECTION 4: BENEFITS
   ========================================================================== */
.benefits-section {
    padding: 80px 0;
    background-color: var(--bg-light);
}

.benefits-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
    margin-top: 50px;
}

.benefit-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 40px;
    display: flex;
    gap: 24px;
    transition: var(--transition-normal);
    box-shadow: var(--shadow-sm);
}

.benefit-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.benefit-icon-box {
    flex-shrink: 0;
    width: 60px;
    height: 60px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.benefit-svg {
    width: 30px;
    height: 30px;
}

.benefit-card-title {
    font-size: 1.375rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 10px;
}

.benefit-card-desc {
    font-size: 0.9375rem;
    color: var(--text-muted);
}

/* ==========================================================================
   SECTION 5: STRUCTURE & TECHNOLOGY
   ========================================================================== */
.structure-section {
    padding: 80px 0;
    background-color: white;
}

.structure-layout {
    display: grid;
    grid-template-columns: 0.95fr 1.05fr;
    gap: 48px;
    align-items: center;
    margin-top: 60px;
}

.structure-img-col {
    display: flex;
    justify-content: center;
}

.structure-img-wrapper {
    position: relative;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-premium);
    border: 8px solid var(--bg-light);
}

.structure-img {
    width: 100%;
    height: auto;
    transition: var(--transition-slow);
}

.structure-img-wrapper:hover .structure-img {
    transform: scale(1.02);
}

.structure-img-overlay {
    position: absolute;
    top: 20px;
    right: 20px;
    background: rgba(2, 132, 199, 0.9);
    color: white;
    padding: 8px 18px;
    border-radius: 100px;
    font-size: 0.875rem;
    font-weight: 700;
    box-shadow: var(--shadow-md);
}

.structure-content-col {
    display: flex;
    flex-direction: column;
    gap: 32px;
}

.struct-feature {
    display: flex;
    gap: 20px;
}

.struct-number {
    flex-shrink: 0;
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary);
    width: 44px;
    height: 44px;
    background-color: var(--primary-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.struct-text h3 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 8px;
}

.struct-text p {
    font-size: 0.9375rem;
    color: var(--text-muted);
}

/* ==========================================================================
   SECTION 6: SUITABLE USERS
   ========================================================================== */
.suitable-section {
    padding: 80px 0;
    background-color: var(--bg-light);
}

.suitable-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 20px;
    margin-top: 50px;
}

.suitable-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 30px 20px;
    text-align: center;
    transition: var(--transition-normal);
}

.suitable-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.suit-emoji {
    font-size: 2.5rem;
    margin-bottom: 16px;
    display: block;
}

.suitable-card h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--dark);
}

.suitable-card p {
    font-size: 0.875rem;
    color: var(--text-muted);
    line-height: 1.5;
}

/* ==========================================================================
   SECTION 7: SOCKS COMBO
   ========================================================================== */
.combo-section {
    padding: 80px 0;
    background-color: white;
}

.combo-container {
    display: grid;
    grid-template-columns: 0.9fr 1.1fr;
    gap: 50px;
    align-items: center;
}

.combo-image-col {
    position: relative;
}

.combo-img-wrapper {
    position: relative;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-premium);
    border: 6px solid var(--bg-light);
}

.combo-img {
    width: 100%;
    height: auto;
}

.combo-img-tag {
    position: absolute;
    bottom: 20px;
    right: 20px;
    background-color: var(--secondary);
    color: white;
    padding: 8px 16px;
    border-radius: 100px;
    font-size: 0.875rem;
    font-weight: 700;
}

.combo-content-col .section-title {
    margin-top: 8px;
}

.combo-intro {
    font-size: 1.125rem;
    margin-bottom: 30px;
}

.socks-features {
    display: flex;
    flex-direction: column;
    gap: 20px;
    margin-bottom: 40px;
}

.sock-feat-item {
    display: flex;
    gap: 16px;
}

.sock-icon-bullet {
    flex-shrink: 0;
    width: 18px;
    height: 18px;
    background-color: var(--secondary-light);
    border: 2px solid var(--secondary);
    border-radius: 50%;
    margin-top: 4px;
}

.sock-feat-item div {
    font-size: 0.9375rem;
    color: var(--text-dark);
}

.sock-feat-item strong {
    color: var(--dark);
}

/* ==========================================================================
   SECTION 8: USAGE TIMELINE
   ========================================================================== */
.usage-section {
    padding: 80px 0;
    background-color: var(--bg-light);
}

.timeline {
    position: relative;
    max-width: 800px;
    margin: 60px auto 0;
    padding-left: 30px;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 15px;
    top: 5px;
    bottom: 5px;
    width: 3px;
    background-color: var(--primary-light);
}

.timeline-item {
    position: relative;
    margin-bottom: 40px;
}

.timeline-item:last-child {
    margin-bottom: 0;
}

.timeline-dot {
    position: absolute;
    left: -30px;
    top: 4px;
    width: 32px;
    height: 32px;
    background-color: var(--primary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.875rem;
    font-weight: 700;
    border: 4px solid var(--bg-light);
    z-index: 1;
}

.timeline-content {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 28px;
    box-shadow: var(--shadow-sm);
}

.timeline-time {
    font-size: 0.8125rem;
    font-weight: 700;
    color: var(--primary-hover);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    display: block;
    margin-bottom: 6px;
}

.timeline-content h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.timeline-content p {
    font-size: 0.9375rem;
    color: var(--text-muted);
}

.usage-warning-box {
    max-width: 800px;
    margin: 50px auto 0;
    background-color: var(--warning-bg);
    border: 1px solid var(--warning-border);
    padding: 24px 30px;
    border-radius: var(--border-radius-md);
    color: var(--warning);
    font-size: 0.9375rem;
    line-height: 1.6;
}

/* ==========================================================================
   SECTION 9: WHY CHOOSE VIETHEALTH
   ========================================================================== */
.why-section {
    padding: 80px 0;
    background-color: white;
}

.why-container {
    display: grid;
    grid-template-columns: 1.15fr 0.85fr;
    gap: 50px;
    align-items: center;
}

.why-intro {
    font-size: 1.125rem;
    margin-bottom: 30px;
}

.why-points-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.why-point-item {
    display: flex;
    gap: 16px;
}

.why-point-icon {
    flex-shrink: 0;
    width: 22px;
    height: 22px;
    background-color: var(--primary-light);
    color: var(--primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 700;
    margin-top: 4px;
}

.why-point-item div {
    font-size: 0.9375rem;
    color: var(--text-dark);
}

.why-point-item strong {
    color: var(--dark);
}

.why-image-col {
    display: flex;
    justify-content: center;
}

.why-img-box {
    position: relative;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-premium);
    border: 6px solid var(--bg-light);
}

.why-img {
    width: 100%;
    height: auto;
}

.why-badge {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    background: linear-gradient(360deg, rgba(15, 23, 42, 0.9) 0%, rgba(15, 23, 42, 0.4) 100%);
    color: white;
    padding: 20px;
    text-align: center;
    font-size: 0.9375rem;
    font-weight: 600;
}

/* ==========================================================================
   SECTION 10: CONSULTATION PROCESS
   ========================================================================== */
.process-section {
    padding: 80px 0;
    background-color: var(--bg-light);
}

.process-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    margin-top: 50px;
}

.process-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 36px 24px;
    position: relative;
    box-shadow: var(--shadow-sm);
    transition: var(--transition-normal);
}

.process-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.process-num {
    position: absolute;
    top: 24px;
    right: 24px;
    font-size: 2.25rem;
    font-weight: 800;
    color: var(--primary-light);
    line-height: 1;
}

.process-title {
    font-size: 1.1875rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 12px;
    padding-right: 30px;
}

.process-desc {
    font-size: 0.875rem;
    color: var(--text-muted);
}

/* ==========================================================================
   SECTION 11: FAQ
   ========================================================================== */
.faq-section {
    padding: 80px 0;
    background-color: white;
}

.faq-container {
    max-width: 800px;
    margin: 50px auto 0;
}

.faq-item {
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    margin-bottom: 16px;
    background-color: var(--bg-light);
    overflow: hidden;
    transition: var(--transition-normal);
}

.faq-item:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-sm);
}

.faq-question {
    width: 100%;
    padding: 20px 24px;
    background: none;
    border: none;
    text-align: left;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-family: var(--font-sans);
    font-size: 1.0625rem;
    font-weight: 700;
    color: var(--dark);
    cursor: pointer;
    gap: 16px;
}

.faq-question:hover {
    color: var(--primary-hover);
}

.faq-icon-arrow {
    font-size: 1.25rem;
    font-weight: 400;
    transition: var(--transition-normal);
    color: var(--primary);
    flex-shrink: 0;
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease-out;
}

.faq-answer-content {
    padding: 0 24px 20px;
    font-size: 0.9375rem;
    color: var(--text-dark);
    line-height: 1.6;
    border-top: 1px solid var(--border-color);
    padding-top: 16px;
}

.faq-item.active {
    background-color: white;
    border-color: var(--primary);
}

.faq-item.active .faq-icon-arrow {
    transform: rotate(45deg);
    color: var(--warning);
}

/* ==========================================================================
   SECTION 12: REGISTRATION FORM & QUICK INFO
   ========================================================================== */
.form-section {
    padding: 80px 0;
    background-color: var(--bg-light);
}

.form-container {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 48px;
}

.form-wrapper-block {
    background-color: white;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: 48px;
    box-shadow: var(--shadow-md);
}

.form-block-title {
    font-size: 1.75rem;
    font-weight: 800;
}

.form-block-subtitle {
    font-size: 0.9375rem;
    color: var(--text-muted);
    margin-bottom: 30px;
}

.consult-form {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.form-label {
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--dark);
}

.form-input, .form-textarea {
    font-family: var(--font-sans);
    font-size: 0.9375rem;
    padding: 12px 16px;
    border-radius: var(--border-radius-sm);
    border: 1px solid var(--border-color);
    background-color: var(--bg-light);
    color: var(--dark);
    transition: var(--transition-fast);
}

.form-input:focus, .form-textarea:focus {
    outline: none;
    border-color: var(--primary);
    background-color: white;
    box-shadow: 0 0 0 3px rgba(2, 132, 199, 0.15);
}

.checkbox-group {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px 20px;
    margin-top: 4px;
}

.checkbox-label {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    font-size: 0.875rem;
    color: var(--text-dark);
    cursor: pointer;
}

.checkbox-label input[type="checkbox"] {
    margin-top: 4px;
    width: 16px;
    height: 16px;
    accent-color: var(--primary);
}

.info-wrapper-block {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.quick-contact-card {
    background-color: white;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 30px;
    box-shadow: var(--shadow-sm);
}

.info-card-tag {
    display: inline-block;
    background-color: var(--warning-bg);
    color: var(--warning);
    font-size: 0.75rem;
    font-weight: 700;
    padding: 4px 10px;
    border-radius: 100px;
    margin-bottom: 12px;
}

.quick-contact-card h3 {
    font-size: 1.25rem;
    margin-bottom: 20px;
}

.info-phone-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.phone-link {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.125rem;
    color: var(--dark);
}

.phone-link:hover {
    color: var(--primary);
}

.phone-icon {
    font-size: 1.375rem;
}

.quick-links-card {
    background-color: white;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 30px;
    box-shadow: var(--shadow-sm);
}

.quick-links-card h3 {
    font-size: 1.25rem;
    margin-bottom: 20px;
}

.links-list {
    display: flex;
    flex-direction: column;
    gap: 14px;
}

.link-item {
    font-size: 0.9375rem;
}

.link-label {
    font-weight: 600;
    color: var(--text-muted);
    display: block;
    margin-bottom: 4px;
}

.certification-box {
    background-color: var(--primary-light);
    border: 1px solid rgba(2, 132, 199, 0.15);
    border-radius: var(--border-radius-md);
    padding: 24px;
    display: flex;
    gap: 16px;
}

.cert-icon-wrapper {
    font-size: 2rem;
    line-height: 1;
}

.certification-box h4 {
    font-size: 1rem;
    font-weight: 700;
    color: var(--primary-hover);
    margin-bottom: 6px;
}

.certification-box p {
    font-size: 0.8125rem;
    color: var(--text-dark);
    line-height: 1.5;
}

/* ==========================================================================
   SECTION 13: FOOTER & LEGAL DISCLAIMER
   ========================================================================== */
.footer-section {
    background-color: var(--dark);
    color: #94a3b8; /* Slate 400 */
    padding-top: 80px;
}

.footer-container {
    display: grid;
    grid-template-columns: 0.8fr 1.2fr 1fr;
    gap: 48px;
    padding-bottom: 50px;
    border-bottom: 1px solid #334155; /* Slate 700 */
}

.footer-col {
    display: flex;
    flex-direction: column;
}

.footer-logo {
    font-size: 1.75rem;
    font-weight: 800;
    color: white;
    margin-bottom: 20px;
}

.footer-about {
    font-size: 0.875rem;
    line-height: 1.7;
    margin-bottom: 24px;
}

.footer-socials a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background-color: #1e293b;
    color: white;
    border-radius: 50%;
    transition: var(--transition-fast);
}

.footer-socials a:hover {
    background-color: var(--primary);
    transform: translateY(-2px);
}

.footer-title {
    color: white;
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 24px;
    position: relative;
    padding-bottom: 10px;
}

.footer-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 40px;
    height: 2px;
    background-color: var(--primary);
}

.footer-address-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
    font-size: 0.875rem;
}

.footer-address-list strong {
    color: white;
}

.footer-contact-info {
    display: flex;
    flex-direction: column;
    gap: 14px;
    font-size: 0.875rem;
}

.footer-contact-info a {
    color: #cbd5e1;
}

.footer-contact-info a:hover {
    color: var(--primary);
}

.disclaimer-container {
    padding: 30px 24px;
    border-bottom: 1px solid #334155;
}

.medical-disclaimer {
    font-size: 0.75rem;
    line-height: 1.6;
    color: #64748b; /* Slate 500 */
    text-align: justify;
}

.footer-bottom {
    padding: 24px 0;
    background-color: #0b0f19;
    font-size: 0.8125rem;
}

.footer-bottom-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

.footer-bottom-links a {
    color: #64748b;
    margin: 0 8px;
}

.footer-bottom-links a:hover {
    color: var(--primary);
}

/* ==========================================================================
   STICKY MOBILE CTA BOTTOM BAR
   ========================================================================== */
.mobile-cta-bar {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 60px;
    background-color: white;
    box-shadow: 0 -4px 10px rgba(0,0,0,0.08);
    display: none; /* Desktop ẩn */
    grid-template-columns: repeat(3, 1fr);
    z-index: 1001;
}

.mobile-cta-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 0.75rem;
    font-weight: 700;
    text-decoration: none;
    transition: var(--transition-fast);
}

.m-cta-icon {
    font-size: 1.125rem;
    margin-bottom: 2px;
}

.bg-orange-solid { background-color: var(--accent); }
.bg-orange-solid:hover { background-color: var(--accent-hover); }

.bg-teal-solid { background-color: var(--secondary); }
.bg-teal-solid:hover { background-color: var(--secondary-hover); }

.bg-blue-solid { background-color: var(--primary); }
.bg-blue-solid:hover { background-color: var(--primary-hover); }

/* ==========================================================================
   INTERSECTION OBSERVER FADE-IN ANIMATION
   ========================================================================== */
.fade-in-up {
    opacity: 0;
    transform: translateY(25px);
    transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1), transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.fade-in-up.active {
    opacity: 1;
    transform: translateY(0);
}

/* ==========================================================================
   RESPONSIVE DESIGN (MEDIA QUERIES)
   ========================================================================== */

/* Laptop / Desktop nhỏ (1024px) */
@media (max-width: 1024px) {
    body {
        font-size: 1rem;
    }
    
    .hero-title {
        font-size: 2.75rem;
    }
    
    .hero-container {
        gap: 30px;
    }
    
    .warning-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 20px;
    }
    
    .suitable-grid {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .form-container {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .footer-container {
        grid-template-columns: 1fr 1fr;
        gap: 30px;
    }
    
    .footer-col:first-child {
        grid-column: span 2;
    }
}

/* Tablet (768px) */
@media (max-width: 768px) {
    :root {
        --header-height: 70px;
    }
    
    /* Show Hamburger & Hide Desktop Menu */
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: -100%;
        width: 100%;
        height: calc(100vh - var(--header-height));
        background-color: white;
        box-shadow: 0 4px 6px rgba(0,0,0,0.05);
        transition: var(--transition-normal);
        padding: 40px 24px;
        z-index: 999;
    }
    
    .nav-menu.open {
        left: 0;
    }
    
    .nav-menu ul {
        flex-direction: column;
        gap: 24px;
        align-items: center;
    }
    
    .nav-link {
        font-size: 1.125rem;
    }
    
    .btn-header {
        display: none; /* Ẩn nút cta header trên mobile để menu gọn */
    }
    
    /* Hamburger Active Animation */
    .hamburger.active .bar:nth-child(1) {
        transform: translateY(9px) rotate(45deg);
    }
    
    .hamburger.active .bar:nth-child(2) {
        opacity: 0;
    }
    
    .hamburger.active .bar:nth-child(3) {
        transform: translateY(-9px) rotate(-45deg);
    }
    
    /* Hero layout stack vertical */
    .hero-container {
        grid-template-columns: 1fr;
        gap: 40px;
        text-align: center;
    }
    
    .badge-container {
        justify-content: center;
    }
    
    .hero-features-list {
        align-items: center;
    }
    
    .hero-cta-buttons {
        justify-content: center;
    }
    
    .hero-img-box {
        max-width: 500px;
    }
    
    /* Warning section stack vertical */
    .warning-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    
    /* Benefits grid stack vertical */
    .benefits-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    
    .benefit-card {
        padding: 30px;
    }
    
    /* Structure section vertical */
    .structure-layout {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .structure-img-col {
        order: 2; /* Đẩy ảnh xuống dưới thông tin cấu tạo trên tablet/mobile */
    }
    
    /* Combo layout vertical */
    .combo-container {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .combo-content-col {
        text-align: center;
    }
    
    .socks-features {
        align-items: flex-start;
        text-align: left;
    }
    
    .combo-cta {
        display: flex;
        justify-content: center;
    }
    
    /* Timeline left adjustment */
    .timeline {
        padding-left: 24px;
    }
    
    .timeline::before {
        left: 10px;
    }
    
    .timeline-dot {
        left: -26px;
        width: 28px;
        height: 28px;
        font-size: 0.8rem;
    }
    
    /* Why Viethealth vertical */
    .why-container {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .why-image-col {
        order: 2;
    }
    
    .why-intro {
        text-align: center;
    }
    
    /* Process grid wrap */
    .process-grid {
        grid-template-columns: 1fr 1fr;
        gap: 20px;
    }
    
    /* Form block padding */
    .form-wrapper-block {
        padding: 30px 20px;
    }
    
    .checkbox-group {
        grid-template-columns: 1fr;
        gap: 10px;
    }
    
    /* Show Sticky Mobile CTA Bar & Add Padding to body */
    body {
        padding-bottom: 60px; /* Thừa khoảng trống để tránh đè bottom bar */
    }
    
    .mobile-cta-bar {
        display: grid;
    }
    
    .back-to-top {
        bottom: 80px; /* Nhấc nút back to top lên trên mobile bar */
        right: 20px;
        width: 44px;
        height: 44px;
    }
}

/* Điện thoại nhỏ (480px) */
@media (max-width: 480px) {
    .section-title {
        font-size: 1.75rem;
    }
    
    .hero-title {
        font-size: 2.25rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .hero-cta-buttons .btn {
        width: 100%;
    }
    
    .suitable-grid {
        grid-template-columns: 1fr;
    }
    
    .process-grid {
        grid-template-columns: 1fr;
    }
    
    .faq-question {
        padding: 16px;
        font-size: 0.9375rem;
    }
    
    .faq-answer-content {
        padding: 0 16px 16px;
        font-size: 0.875rem;
    }
    
    .footer-container {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    
    .footer-col:first-child {
        grid-column: span 1;
    }
    
    .footer-bottom-container {
        flex-direction: column;
        text-align: center;
    }
}