/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    --dark-bg: #1a202c;
    --card-bg: #2d3748;
    --text-primary: #ffffff;
    --text-secondary: #cbd5e0;
    --border-color: #4a5568;
    --success-color: #48bb78;
    --gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

body {
    font-family: 'Poppins', sans-serif;
    background: var(--dark-bg);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

/* Header Styles */
.header {
    background: var(--gradient);
    padding: 60px 20px;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    position: relative;
    overflow: hidden;
}

.header::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255, 255, 255, 0.1) 1px, transparent 1px);
    background-size: 50px 50px;
    animation: moveBackground 20s linear infinite;
}

@keyframes moveBackground {
    0% { transform: translate(0, 0); }
    100% { transform: translate(50px, 50px); }
}

.header-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 10px;
    position: relative;
    z-index: 1;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.header-subtitle {
    font-size: 1.2rem;
    font-weight: 300;
    opacity: 0.95;
    position: relative;
    z-index: 1;
}

/* Main Content */
.main {
    flex: 1;
    padding: 40px 20px;
}

/* Stats Overview */
.stats-overview {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 40px;
}

.stat-card {
    background: var(--card-bg);
    padding: 30px;
    border-radius: 15px;
    display: flex;
    align-items: center;
    gap: 20px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid var(--border-color);
}

.stat-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.3);
}

.stat-icon {
    font-size: 3rem;
    animation: pulse 2s ease-in-out infinite;
}

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

.stat-content {
    flex: 1;
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-color);
    margin-bottom: 5px;
}

.stat-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* Filters */
.filters {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

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

.filter-group label {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.filter-group select,
.filter-group input {
    padding: 12px 16px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-primary);
    font-size: 1rem;
    font-family: 'Poppins', sans-serif;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.filter-group select:focus,
.filter-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.2);
}

/* Loading */
.loading {
    text-align: center;
    padding: 60px 20px;
    display: none;
}

.loading.active {
    display: block;
}

.spinner {
    width: 60px;
    height: 60px;
    margin: 0 auto 20px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* Countries List */
.countries-list {
    display: grid;
    gap: 20px;
}

.country-card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 25px;
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    gap: 20px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid var(--border-color);
    opacity: 0;
    animation: fadeInUp 0.5s ease forwards;
}

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

.country-card:hover {
    transform: translateX(5px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.3);
}

.country-rank {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    min-width: 60px;
    text-align: center;
}

.country-info {
    flex: 1;
}

.country-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 10px;
}

.country-flag {
    font-size: 2.5rem;
}

.country-name {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.country-details {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.country-detail {
    display: flex;
    align-items: center;
    gap: 5px;
}

.country-detail-icon {
    font-size: 1rem;
}

.country-population {
    text-align: right;
}

.population-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-color);
    margin-bottom: 5px;
}

.population-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.population-bar {
    width: 100%;
    height: 6px;
    background: var(--border-color);
    border-radius: 3px;
    margin-top: 8px;
    overflow: hidden;
}

.population-bar-fill {
    height: 100%;
    background: var(--gradient);
    border-radius: 3px;
    transition: width 1s ease;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 4rem;
    margin-bottom: 20px;
    opacity: 0.5;
}

.empty-state-text {
    font-size: 1.2rem;
}

/* Footer */
.footer {
    background: var(--card-bg);
    padding: 30px 20px;
    text-align: center;
    margin-top: 60px;
    border-top: 1px solid var(--border-color);
}

.footer p {
    color: var(--text-secondary);
    margin: 5px 0;
}

.footer-note {
    font-size: 0.9rem;
    opacity: 0.8;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-title {
        font-size: 2rem;
    }

    .header-subtitle {
        font-size: 1rem;
    }

    .country-card {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .country-rank {
        font-size: 1.8rem;
    }

    .country-header {
        justify-content: center;
    }

    .country-details {
        justify-content: center;
    }

    .country-population {
        text-align: center;
    }

    .stat-value {
        font-size: 1.5rem;
    }
}

@media (max-width: 480px) {
    .header-title {
        font-size: 1.5rem;
    }

    .stat-card {
        padding: 20px;
    }

    .stat-icon {
        font-size: 2rem;
    }
}