:root {
    /* Colors - Light Theme */
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --secondary-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --accent-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    
    --bg-primary: #f8f9ff;
    --bg-secondary: #ffffff;
    --text-primary: #1a1a2e;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    
    --glass-bg: rgba(255, 255, 255, 0.25);
    --glass-border: rgba(255, 255, 255, 0.4);
    --glass-shadow: rgba(31, 38, 135, 0.15);
    
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    
    --zalo-color: #0068ff;
    --whatsapp-color: #25d366;
    
    --border-radius: 20px;
    --transition-speed: 0.3s;
}

[data-theme="dark"] {
    --bg-primary: #0f0f23;
    --bg-secondary: #1a1a2e;
    --text-primary: #e2e8f0;
    --text-secondary: #cbd5e0;
    --text-muted: #a0aec0;
    
    --glass-bg: rgba(26, 26, 46, 0.4);
    --glass-border: rgba(255, 255, 255, 0.1);
    --glass-shadow: rgba(0, 0, 0, 0.3);
}

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

body {
    font-family: 'DM Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    position: relative;
    min-height: 100vh;
    transition: background 0.5s ease, color 0.5s ease;
}

/* Background Elements */
.bg-gradient {
    position: fixed;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: var(--primary-gradient);
    opacity: 0.15;
    z-index: -2;
    animation: gradientShift 20s ease infinite;
}

@keyframes gradientShift {
    0%, 100% { transform: translate(0, 0) rotate(0deg); }
    25% { transform: translate(5%, 5%) rotate(90deg); }
    50% { transform: translate(-5%, 5%) rotate(180deg); }
    75% { transform: translate(5%, -5%) rotate(270deg); }
}

.bg-pattern {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        radial-gradient(circle at 20% 50%, rgba(102, 126, 234, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(118, 75, 162, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 40% 20%, rgba(79, 172, 254, 0.1) 0%, transparent 50%);
    z-index: -1;
    animation: patternFloat 30s ease-in-out infinite;
}

@keyframes patternFloat {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-20px); }
}

/* Theme Toggle */
.theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    box-shadow: 0 8px 32px var(--glass-shadow);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    transition: all var(--transition-speed) ease;
}

.theme-toggle:hover {
    transform: scale(1.1) rotate(10deg);
    box-shadow: 0 12px 40px var(--glass-shadow);
}

.theme-toggle .sun-icon,
.theme-toggle .moon-icon {
    position: absolute;
    transition: all 0.3s ease;
}

.theme-toggle .moon-icon {
    opacity: 0;
    transform: scale(0.5) rotate(-90deg);
}

[data-theme="dark"] .theme-toggle .sun-icon {
    opacity: 0;
    transform: scale(0.5) rotate(90deg);
}

[data-theme="dark"] .theme-toggle .moon-icon {
    opacity: 1;
    transform: scale(1) rotate(0deg);
}

/* Container */
.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    position: relative;
    z-index: 1;
}

/* Glass Card Effect */
.glass-card {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: var(--border-radius);
    border: 1px solid var(--glass-border);
    box-shadow: 0 8px 32px var(--glass-shadow);
    padding: 30px;
    margin-bottom: 30px;
    transition: all var(--transition-speed) ease;
}

.glass-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 48px var(--glass-shadow);
    border-color: rgba(255, 255, 255, 0.6);
}

/* Fade In Animation */
.fade-in {
    animation: fadeIn 0.8s ease forwards;
    opacity: 0;
}

.fade-in:nth-child(1) { animation-delay: 0.1s; }
.fade-in:nth-child(2) { animation-delay: 0.2s; }
.fade-in:nth-child(3) { animation-delay: 0.3s; }
.fade-in:nth-child(4) { animation-delay: 0.4s; }
.fade-in:nth-child(5) { animation-delay: 0.5s; }
.fade-in:nth-child(6) { animation-delay: 0.6s; }

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Header */
.header {
    text-align: center;
    padding: 40px 0;
}

.logo-wrapper {
    margin-bottom: 20px;
}

.logo {
    width: 100px;
    height: 100px;
    border-radius: 50%;
    object-fit: cover;
    border: 3px solid var(--glass-border);
    box-shadow: 0 8px 32px var(--glass-shadow);
    transition: all var(--transition-speed) ease;
    animation: float 3s ease-in-out infinite;
}

.logo:hover {
    transform: scale(1.1) rotate(5deg);
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.site-title {
    font-family: 'Outfit', sans-serif;
    font-size: 3rem;
    font-weight: 800;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 10px;
    letter-spacing: -1px;
}

.site-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* Section Title */
.section-title {
    font-family: 'Outfit', sans-serif;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 25px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.section-title.highlight {
    background: var(--secondary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-title svg {
    color: #667eea;
}

/* QR Section */
.qr-wrapper {
    position: relative;
    display: flex;
    justify-content: center;
    margin: 30px 0;
}

.qr-glow {
    position: absolute;
    width: 280px;
    height: 280px;
    background: var(--accent-gradient);
    border-radius: 20px;
    filter: blur(40px);
    opacity: 0.3;
    animation: pulse 3s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); opacity: 0.3; }
    50% { transform: scale(1.1); opacity: 0.5; }
}

.qr-container {
    position: relative;
    width: 280px;
    height: 280px;
    background: white;
    border-radius: 20px;
    padding: 15px;
    box-shadow: 0 10px 50px rgba(0, 0, 0, 0.15);
    display: flex;
    align-items: center;
    justify-content: center;
}

.qr-image {
    width: 100%;
    height: 100%;
    object-fit: contain;
    border-radius: 10px;
}

.qr-skeleton {
    position: absolute;
    top: 15px;
    left: 15px;
    right: 15px;
    bottom: 15px;
    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
    background-size: 200% 100%;
    border-radius: 10px;
    animation: shimmer 1.5s infinite;
}

@keyframes shimmer {
    0% { background-position: -200% 0; }
    100% { background-position: 200% 0; }
}

.qr-skeleton.hidden {
    display: none;
}

/* Payment Info */
.payment-info {
    background: var(--bg-secondary);
    border-radius: 15px;
    padding: 20px;
    margin: 25px 0;
    border: 1px solid var(--glass-border);
}

.info-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 0;
    border-bottom: 1px solid var(--glass-border);
}

.info-row:last-child {
    border-bottom: none;
}

.info-label {
    font-weight: 500;
    color: var(--text-muted);
    font-size: 0.95rem;
}

.info-value {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 1rem;
    text-align: right;
}

.transfer-content {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 700;
}

/* Buttons */
.button-group {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
    margin-top: 25px;
}

.btn {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 15px 25px;
    border: none;
    border-radius: 12px;
    font-family: 'DM Sans', sans-serif;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-speed) ease;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.btn:active {
    transform: translateY(0);
}

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

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

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

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

/* Ripple Effect */
.btn-ripple {
    position: absolute;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.6);
    transform: scale(0);
    pointer-events: none;
}

.btn-ripple.active {
    animation: ripple 0.6s ease-out;
}

@keyframes ripple {
    to {
        transform: scale(4);
        opacity: 0;
    }
}

/* Bank Grid */
.bank-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    gap: 15px;
    margin-top: 20px;
}

.bank-item {
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: 15px;
    text-align: center;
    cursor: pointer;
    border: 2px solid transparent;
    transition: all var(--transition-speed) ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.bank-item:hover {
    transform: translateY(-5px);
    border-color: #667eea;
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.2);
}

.bank-logo {
    width: 50px;
    height: 50px;
    object-fit: contain;
    border-radius: 8px;
}

.bank-name {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-primary);
}

/* Steps Container */
.steps-container {
    margin-top: 30px;
}

.step-item {
    display: flex;
    gap: 20px;
    margin-bottom: 25px;
    animation: slideIn 0.5s ease forwards;
    opacity: 0;
}

.step-item:nth-child(1) { animation-delay: 0.1s; }
.step-item:nth-child(2) { animation-delay: 0.2s; }
.step-item:nth-child(3) { animation-delay: 0.3s; }
.step-item:nth-child(4) { animation-delay: 0.4s; }
.step-item:nth-child(5) { animation-delay: 0.5s; }
.step-item:nth-child(6) { animation-delay: 0.6s; }
.step-item:nth-child(7) { animation-delay: 0.7s; }

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.step-number {
    flex-shrink: 0;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--primary-gradient);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: 'Outfit', sans-serif;
    font-size: 1.3rem;
    font-weight: 700;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

.step-content {
    flex: 1;
}

.step-title {
    font-family: 'Outfit', sans-serif;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 5px;
}

.step-desc {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* Bill Section */
.bill-description {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 20px;
    text-align: center;
}

.contact-info {
    margin-top: 25px;
    padding: 20px;
    background: var(--bg-secondary);
    border-radius: 12px;
    border: 1px solid var(--glass-border);
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 0;
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.contact-item svg {
    color: #667eea;
}

.contact-item strong {
    color: var(--text-primary);
}

/* Footer */
.footer {
    text-align: center;
    padding: 30px 0;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.footer-note {
    margin-top: 10px;
    font-size: 0.85rem;
    opacity: 0.8;
}

/* Popup */
.popup {
    position: fixed;
    bottom: -200px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 25px 35px;
    box-shadow: 0 10px 40px var(--glass-shadow);
    z-index: 2000;
    transition: bottom 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
    min-width: 300px;
}

.popup.show {
    bottom: 30px;
}

.popup-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.popup-icon {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background: var(--success-color);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    animation: popupPulse 0.6s ease;
}

@keyframes popupPulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.1); }
}

.popup-title {
    font-family: 'Outfit', sans-serif;
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
}

.popup-message {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin: 0;
    text-align: center;
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 3000;
}

.loading-overlay.show {
    display: flex;
}

.loading-spinner {
    text-align: center;
    color: white;
}

.spinner {
    width: 60px;
    height: 60px;
    border: 4px solid rgba(255, 255, 255, 0.3);
    border-top: 4px solid white;
    border-radius: 50%;
    margin: 0 auto 20px;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.loading-spinner p {
    font-size: 1.1rem;
    font-weight: 500;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }

    .site-title {
        font-size: 2rem;
    }

    .glass-card {
        padding: 20px;
    }

    .qr-container {
        width: 240px;
        height: 240px;
    }

    .qr-glow {
        width: 240px;
        height: 240px;
    }

    .button-group {
        grid-template-columns: 1fr;
    }

    .bank-grid {
        grid-template-columns: repeat(auto-fill, minmax(80px, 1fr));
        gap: 10px;
    }

    .bank-logo {
        width: 40px;
        height: 40px;
    }

    .step-number {
        width: 40px;
        height: 40px;
        font-size: 1.1rem;
    }

    .step-title {
        font-size: 1rem;
    }

    .step-desc {
        font-size: 0.9rem;
    }

    .popup {
        min-width: 280px;
        padding: 20px 25px;
    }

    .theme-toggle {
        width: 45px;
        height: 45px;
        top: 15px;
        right: 15px;
    }
}

@media (max-width: 480px) {
    .site-title {
        font-size: 1.75rem;
    }

    .section-title {
        font-size: 1.25rem;
    }

    .qr-container {
        width: 200px;
        height: 200px;
    }

    .qr-glow {
        width: 200px;
        height: 200px;
    }

    .info-row {
        flex-direction: column;
        align-items: flex-start;
        gap: 5px;
    }

    .info-value {
        text-align: left;
    }
}

/* Print Styles */
@media print {
    .theme-toggle,
    .button-group,
    .bank-section,
    .bill-section,
    .footer {
        display: none;
    }

    .glass-card {
        box-shadow: none;
        border: 1px solid #ddd;
    }
}