/* 
 * CSS Styling cho Personal Website
 * Áp dụng Modern Design: Dark Mode, Glassmorphism 
 */

:root {
    /* Color Palette */
    --color-bg: #09090b;
    --color-surface: rgba(24, 24, 27, 0.65);
    --color-border: rgba(255, 255, 255, 0.1);
    
    --color-text-main: #f4f4f5;
    --color-text-muted: #a1a1aa;
    
    --color-brand: #3b82f6;
    --color-brand-glow: rgba(59, 130, 246, 0.4);
    
    --color-vr: #8b5cf6;
    --color-vr-glow: rgba(139, 92, 246, 0.3);
    
    --color-error: #ef4444;
    --color-error-bg: rgba(239, 68, 68, 0.1);

    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-full: 9999px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

body {
    background-color: var(--color-bg);
    color: var(--color-text-main);
    line-height: 1.6;
    min-height: 100vh;
}

/* Typography & Layout */
.header {
    text-align: center;
    padding: 5rem 2rem 3rem;
    position: relative;
    overflow: hidden;
}

.header::before {
    content: '';
    position: absolute;
    top: -50%;
    left: 50%;
    transform: translateX(-50%);
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, var(--color-brand-glow) 0%, transparent 70%);
    z-index: -1;
    opacity: 0.5;
}

.title {
    font-size: 3rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, #ffffff 0%, var(--color-text-muted) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.5rem;
}

.subtitle {
    color: var(--color-text-muted);
    font-size: 1.125rem;
}

.main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem 5rem;
}

/* Projects Grid */
.projects-section-title {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 2rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.projects-section-title::after {
    content: '';
    flex: 1;
    height: 1px;
    background: linear-gradient(90deg, var(--color-border) 0%, transparent 100%);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 2rem;
}

/* Project Card (Glassmorphism) */
.project-card {
    background: var(--color-surface);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    display: flex;
    flex-direction: column;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    overflow: hidden;
}

.project-card:hover {
    transform: translateY(-8px);
    border-color: rgba(255, 255, 255, 0.2);
    box-shadow: 0 20px 40px -10px rgba(0, 0, 0, 0.5), 0 0 20px 0 var(--color-vr-glow);
}

.card-image-wrapper {
    width: 100%;
    aspect-ratio: 16 / 9;
    overflow: hidden;
    background-color: rgba(255, 255, 255, 0.02);
    border-bottom: 1px solid var(--color-border);
}

.card-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s ease;
}

.project-card:hover .card-image {
    transform: scale(1.05); /* Khung hình phóng nhẹ cho cảm giác Premium */
}

.card-content {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    flex-grow: 1;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1rem;
    gap: 1rem;
}

.card-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: #fff;
    line-height: 1.4;
}

.badge {
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-full);
    white-space: nowrap;
}

.vr-badge {
    background: rgba(139, 92, 246, 0.15);
    color: #a78bfa;
    border: 1px solid rgba(139, 92, 246, 0.3);
}

.card-body {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.card-desc {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.vr-support-info {
    background: rgba(0, 0, 0, 0.3);
    padding: 0.75rem;
    border-radius: var(--radius-md);
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-bottom: 1.5rem;
    border: 1px dashed var(--color-border);
}

.vr-support-info strong {
    color: #d8b4fe;
}

.tech-stack {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.tech-tag {
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--color-text-muted);
    background: rgba(255, 255, 255, 0.05);
    padding: 0.25rem 0.6rem;
    border-radius: var(--radius-md);
    border: 1px solid transparent;
    transition: all 0.2s ease;
}

.project-card:hover .tech-tag {
    border-color: var(--color-border);
    color: var(--color-text-main);
}

/* Actions */
.card-footer {
    display: flex;
    gap: 0.75rem;
    margin-top: auto;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    width: 100%;
    padding: 0.65rem 0.5rem;
    border-radius: var(--radius-md);
    font-size: 0.85rem;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.2s ease;
    cursor: pointer;
}

.btn-primary {
    background: linear-gradient(to right, var(--color-brand), #2563eb);
    color: white;
    border: none;
    box-shadow: 0 4px 14px 0 var(--color-brand-glow);
}

.btn-primary:hover {
    filter: brightness(1.1);
    box-shadow: 0 6px 20px 0 var(--color-brand-glow);
}

.btn-secondary {
    background: transparent;
    color: var(--color-text-main);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: rgba(255, 255, 255, 0.2);
}

.btn-icon {
    font-size: 1.1rem;
}

/* States */
.empty-state {
    grid-column: 1 / -1;
    text-align: center;
    color: var(--color-text-muted);
    padding: 4rem 0;
    font-style: italic;
}

.loader {
    grid-column: 1 / -1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 4rem 0;
    color: var(--color-brand);
    font-weight: 500;
}

.loader::after {
    content: '';
    width: 24px;
    height: 24px;
    border: 3px solid var(--color-brand-glow);
    border-top-color: var(--color-brand);
    border-radius: 50%;
    margin-top: 1rem;
    animation: spin 1s infinite linear;
}

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

.error-container {
    grid-column: 1 / -1;
    background: var(--color-error-bg);
    border: 1px solid rgba(239, 68, 68, 0.3);
    border-radius: var(--radius-lg);
    padding: 2rem;
    text-align: center;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.error-container h3 {
    color: var(--color-error);
    font-size: 1.25rem;
}

.error-details {
    margin-top: 0.5rem;
    font-family: ui-monospace, monospace;
    font-size: 0.85rem;
    color: var(--color-error);
    opacity: 0.8;
}

.site-footer {
    text-align: center;
    color: var(--color-text-muted);
    padding: 1.5rem 2rem 2rem;
    font-size: 0.95rem;
}

/* Language Toggle */
.lang-toggle {
    position: absolute;
    top: 1.5rem;
    right: 2rem;
    display: flex;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    overflow: hidden;
    backdrop-filter: blur(8px);
}

.lang-btn {
    background: transparent;
    color: var(--color-text-muted);
    border: none;
    padding: 0.5rem 1rem;
    font-weight: 600;
    font-size: 0.85rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

.lang-btn:hover {
    color: var(--color-text-main);
}

.lang-btn.active {
    background: var(--color-brand);
    color: white;
}

/* Responsive */
@media (max-width: 768px) {
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .title {
        font-size: 2.5rem;
    }
    
    .card-footer {
        flex-direction: column;
    }
}