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

:root {
    --primary-color: #4a90e2;
    --secondary-color: #7b68ee;
    --success-color: #52c41a;
    --warning-color: #faad14;
    --danger-color: #f5222d;
    --text-primary: #1a1a1a;
    --text-secondary: #666;
    --background: #f7f9fc;
    --card-background: #ffffff;
    --border-color: #e8e8e8;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.16);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: var(--text-primary);
    line-height: 1.6;
}

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

header {
    text-align: center;
    padding: 40px 0;
    color: white;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.subtitle {
    font-size: 1.2rem;
    opacity: 0.95;
    margin-bottom: 30px;
}

.language-selector {
    display: flex;
    gap: 10px;
    justify-content: center;
    flex-wrap: wrap;
}

.lang-btn {
    padding: 8px 20px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.9rem;
    font-weight: 500;
    backdrop-filter: blur(10px);
}

.lang-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

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

main {
    background: var(--card-background);
    border-radius: 20px;
    padding: 40px;
    box-shadow: var(--shadow-lg);
    backdrop-filter: blur(10px);
    background: rgba(255, 255, 255, 0.95);
}

.input-section {
    text-align: center;
    margin-bottom: 40px;
}

.input-section label {
    display: block;
    margin-bottom: 15px;
    font-size: 1.1rem;
    color: var(--text-primary);
    font-weight: 500;
}

.date-input {
    padding: 12px 24px;
    font-size: 1.1rem;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    margin-right: 15px;
    transition: all 0.3s ease;
    background: white;
}

.date-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.1);
}

.calculate-btn {
    padding: 12px 36px;
    font-size: 1.1rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 600;
    box-shadow: var(--shadow-sm);
}

.calculate-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

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

.info-card {
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    padding: 30px;
    border-radius: 15px;
    margin-bottom: 30px;
}

.info-card h2 {
    margin-bottom: 20px;
    color: var(--text-primary);
    font-size: 1.5rem;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
}

.info-item {
    background: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: var(--shadow-sm);
}

.info-label {
    display: block;
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 8px;
}

.info-value {
    display: block;
    color: var(--text-primary);
    font-size: 1.4rem;
    font-weight: 600;
}

.milestones-section h2 {
    margin-bottom: 25px;
    color: var(--text-primary);
    font-size: 1.5rem;
}

.milestone-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
}

.milestone-card {
    padding: 20px;
    border-radius: 12px;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.milestone-card.passed {
    background: linear-gradient(135deg, #e8f5e9, #c8e6c9);
    border-color: var(--success-color);
}

.milestone-card.upcoming {
    background: linear-gradient(135deg, #fff3e0, #ffe0b2);
    border-color: var(--warning-color);
}

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

.milestone-card h3 {
    font-size: 1.2rem;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.milestone-date {
    color: var(--text-secondary);
    margin-bottom: 8px;
    font-size: 0.95rem;
}

.milestone-status {
    font-weight: 600;
    font-size: 0.9rem;
}

.milestone-card.passed .milestone-status {
    color: var(--success-color);
}

.milestone-card.upcoming .milestone-status {
    color: var(--warning-color);
}

.countdown-section {
    margin-top: 40px;
}

.countdown-section h2 {
    margin-bottom: 25px;
    color: var(--text-primary);
    font-size: 1.5rem;
    text-align: center;
}

.countdown-card {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 40px;
    border-radius: 20px;
    color: white;
    text-align: center;
    box-shadow: var(--shadow-lg);
}

.countdown-card h3 {
    font-size: 1.8rem;
    margin-bottom: 30px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.countdown-timer {
    display: flex;
    justify-content: center;
    gap: 30px;
    flex-wrap: wrap;
}

.time-unit {
    text-align: center;
}

.time-value {
    display: block;
    font-size: 3rem;
    font-weight: 700;
    line-height: 1;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.time-label {
    font-size: 0.9rem;
    opacity: 0.9;
    text-transform: uppercase;
    letter-spacing: 1px;
}

footer {
    text-align: center;
    padding: 30px 0;
    color: white;
    opacity: 0.9;
}

.hidden {
    display: none;
}

@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    main {
        padding: 25px;
    }
    
    .date-input {
        display: block;
        width: 100%;
        margin: 0 0 15px 0;
    }
    
    .calculate-btn {
        width: 100%;
    }
    
    .milestone-container {
        grid-template-columns: 1fr;
    }
    
    .countdown-timer {
        gap: 20px;
    }
    
    .time-value {
        font-size: 2.5rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 10px;
    }
    
    header {
        padding: 30px 0;
    }
    
    main {
        padding: 20px;
        border-radius: 15px;
    }
    
    .info-grid {
        grid-template-columns: 1fr;
    }
    
    .countdown-card {
        padding: 25px;
    }
    
    .time-value {
        font-size: 2rem;
    }
}