:root {
    /* Color Palette - Light Mode */
    --bg-color: #f8fafc;
    --text-color: #1e293b;
    --text-muted: #64748b;
    --card-bg: #ffffff;
    --card-border: #e2e8f0;
    --primary-color: #0f766e; /* Teal 700 - Deep mountain teal */
    --primary-hover: #0d9488;
    --secondary-color: #f97316; /* Orange 500 - Sunset orange */
    --secondary-bg: #ffedd5;
    --accent-bg: #f1f5f9;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.05), 0 2px 4px -2px rgb(0 0 0 / 0.05);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    
    --header-height: 300px;
    --border-radius: 12px;
}

[data-theme="dark"] {
    /* Color Palette - Dark Mode */
    --bg-color: #0f172a; /* Slate 900 */
    --text-color: #f8fafc;
    --text-muted: #94a3b8;
    --card-bg: #1e293b; /* Slate 800 */
    --card-border: #334155; /* Slate 700 */
    --primary-color: #2dd4bf; /* Teal 400 */
    --primary-hover: #14b8a6;
    --secondary-color: #fb923c; /* Orange 400 */
    --secondary-bg: #431407;
    --accent-bg: #334155;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.2), 0 2px 4px -2px rgb(0 0 0 / 0.2);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.4), 0 4px 6px -4px rgb(0 0 0 / 0.4);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

body {
    font-family: 'Outfit', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    padding-bottom: 60px;
}

/* Header & Hero */
.hero {
    position: relative;
    height: var(--header-height);
    background-image: url('image/ban-si-thau-chai.png');
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: #ffffff;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(180deg, rgba(15, 23, 42, 0.4) 0%, rgba(15, 23, 42, 0.8) 100%);
}

.hero-content {
    position: relative;
    z-index: 1;
    padding: 20px;
    max-width: 800px;
}

.badge {
    background-color: var(--secondary-color);
    color: #ffffff;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    display: inline-block;
    margin-bottom: 12px;
}

.hero h1 {
    font-size: 2.8rem;
    font-weight: 700;
    letter-spacing: 0.05em;
    margin-bottom: 8px;
    text-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

.subtitle {
    font-size: 1.2rem;
    font-weight: 300;
    opacity: 0.9;
    margin-bottom: 16px;
}

.meta-tags {
    display: flex;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
}

.meta-item {
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(4px);
    padding: 6px 16px;
    border-radius: 30px;
    font-size: 0.9rem;
    font-weight: 500;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

/* Layout container */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 24px 16px;
}

.section {
    margin-bottom: 40px;
}

.section-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 8px;
    border-left: 4px solid var(--primary-color);
    padding-left: 12px;
}

/* Info Grid (Stay & Transportation) */
.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
}

.info-card {
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--border-radius);
    padding: 20px;
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.info-card h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--primary-color);
}

.info-card p {
    font-size: 0.95rem;
    color: var(--text-muted);
    margin-bottom: 12px;
}

.price-estimate {
    font-weight: 500;
    color: var(--text-color) !important;
    margin-bottom: 16px !important;
}

.note-text {
    font-size: 0.85rem !important;
    color: var(--secondary-color) !important;
    font-weight: 500;
}

/* Buttons */
.action-buttons {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 16px;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 500;
    text-decoration: none;
    text-align: center;
    cursor: pointer;
    border: none;
    min-height: 44px;
    transition: transform 0.1s ease, filter 0.1s ease;
}

.btn:active {
    transform: scale(0.98);
}

.btn-primary {
    background-color: var(--primary-color);
    color: #ffffff !important;
}

.btn-primary:hover {
    filter: brightness(1.1);
}

.btn-secondary {
    background-color: var(--accent-bg);
    color: var(--text-color);
    border: 1px solid var(--card-border);
}

.btn-secondary:hover {
    background-color: var(--card-border);
}

/* Timeline Selector Tab */
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 20px;
}

.day-selector {
    display: flex;
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    padding: 4px;
    border-radius: 30px;
}

.tab-btn {
    border: none;
    background: none;
    padding: 6px 16px;
    border-radius: 20px;
    font-family: inherit;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    color: var(--text-muted);
}

.tab-btn.active {
    background-color: var(--primary-color);
    color: #ffffff;
}

/* Vertical Timeline */
.timeline {
    position: relative;
    padding-left: 28px;
}

.timeline::before {
    content: '';
    position: absolute;
    top: 10px;
    bottom: 10px;
    left: 9px;
    width: 2px;
    background-color: var(--card-border);
}

.timeline-item {
    position: relative;
    margin-bottom: 24px;
}

.timeline-badge {
    position: absolute;
    left: -28px;
    top: 4px;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background-color: var(--card-bg);
    border: 2px solid var(--primary-color);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--primary-color);
    z-index: 1;
}

.timeline-badge.departure {
    border-color: var(--secondary-color);
    color: var(--secondary-color);
    font-size: 0.7rem;
}

.timeline-content {
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--border-radius);
    padding: 16px;
    box-shadow: var(--shadow);
}

.timeline-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 12px;
    margin-bottom: 8px;
}

.time {
    background-color: var(--accent-bg);
    color: var(--primary-color);
    font-weight: 600;
    font-size: 0.85rem;
    padding: 2px 8px;
    border-radius: 4px;
    white-space: nowrap;
}

.timeline-content .title {
    font-size: 1.1rem;
    font-weight: 600;
    flex-grow: 1;
}

.timeline-content .desc {
    font-size: 0.95rem;
    color: var(--text-muted);
}

.card-img {
    height: 160px;
    background-size: cover;
    background-position: center;
    border-radius: 8px;
    margin-top: 12px;
}

/* Custom Interactive Step Checkbox */
.checkbox-container {
    display: inline-block;
    position: relative;
    cursor: pointer;
    font-size: 22px;
    user-select: none;
    width: 24px;
    height: 24px;
}

.checkbox-container input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    position: absolute;
    top: 0;
    left: 0;
    height: 24px;
    width: 24px;
    background-color: var(--accent-bg);
    border: 1px solid var(--card-border);
    border-radius: 6px;
}

.checkbox-container:hover input ~ .checkmark {
    background-color: var(--card-border);
}

.checkbox-container input:checked ~ .checkmark {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
}

.checkmark:after {
    content: "";
    position: absolute;
    display: none;
}

.checkbox-container input:checked ~ .checkmark:after {
    display: block;
}

.checkbox-container .checkmark:after {
    left: 8px;
    top: 4px;
    width: 6px;
    height: 12px;
    border: solid #ffffff;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

/* Style when checking a timeline item */
.timeline-item.checked .timeline-content {
    opacity: 0.65;
    background-color: var(--accent-bg);
    border-style: dashed;
}

/* Packing Checklist */
.packing-list {
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--border-radius);
    padding: 20px;
    box-shadow: var(--shadow);
}

.pack-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px 0;
    border-bottom: 1px solid var(--card-border);
    cursor: pointer;
}

.pack-item:last-child {
    border-bottom: none;
}

.pack-item input {
    width: 18px;
    height: 18px;
    accent-color: var(--primary-color);
    cursor: pointer;
}

.pack-item input:checked + .pack-text {
    text-decoration: line-through;
    color: var(--text-muted);
}

.pack-text {
    font-size: 0.95rem;
}

/* Theme Toggle Button */
.theme-toggle-btn {
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background-color: var(--primary-color);
    color: #ffffff;
    border: none;
    cursor: pointer;
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.3rem;
    z-index: 100;
}

/* Footer */
footer {
    text-align: center;
    padding: 40px 16px;
    color: var(--text-muted);
    font-size: 0.85rem;
    border-top: 1px solid var(--card-border);
    margin-top: 40px;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    :root {
        --header-height: 220px;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }

    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .day-selector {
        width: 100%;
        justify-content: space-between;
    }

    .tab-btn {
        flex-grow: 1;
        padding: 6px 8px;
        font-size: 0.8rem;
    }

    .timeline-content .title {
        font-size: 1rem;
    }
    
    .timeline-content .desc {
        font-size: 0.88rem;
    }
}

/* Bottom Banner (Tách nền) */
.bottom-banner-container {
    text-align: center;
    margin-top: 30px;
    margin-bottom: -20px;
    padding: 0 16px;
    display: flex;
    justify-content: center;
    align-items: flex-end;
}

.bottom-banner-img {
    max-width: 100%;
    max-height: 250px;
    height: auto;
    object-fit: contain;
    display: block;
}