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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
}

.container {
    max-width: 480px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
}

.header {
    text-align: center;
    margin-bottom: 30px;
}

.header h1 {
    color: white;
    font-size: 2.5em;
    margin-bottom: 20px;
    font-weight: 700;
    text-shadow: 0 2px 10px rgba(0,0,0,0.3);
}

.month-navigation {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px;
    background: rgba(255, 255, 255, 0.2);
    padding: 10px 20px;
    border-radius: 25px;
    backdrop-filter: blur(10px);
}

.nav-btn {
    background: rgba(255, 255, 255, 0.3);
    border: none;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    color: white;
    font-size: 18px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.nav-btn:hover {
    background: rgba(255, 255, 255, 0.5);
    transform: scale(1.1);
}

#currentMonth {
    color: white;
    font-size: 1.2em;
    font-weight: 600;
    min-width: 120px;
}

.calendar-container {
    background: white;
    border-radius: 20px;
    padding: 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
    margin-bottom: 20px;
}

.weekdays {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 5px;
    margin-bottom: 15px;
}

.weekday {
    text-align: center;
    font-weight: 600;
    font-size: 0.9em;
    color: #666;
    padding: 10px 0;
}

.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 8px;
}

.calendar-day {
    aspect-ratio: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    border: 2px solid #e0e0e0;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    background: white;
}

.calendar-day:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.calendar-day.checked {
    background: linear-gradient(45deg, #4CAF50, #45a049);
    border-color: #4CAF50;
    color: white;
}

.calendar-day.today {
    border-color: #2196F3;
    border-width: 3px;
    background: rgba(33, 150, 243, 0.1);
}

.day-number {
    font-weight: 600;
    font-size: 1.1em;
}

.check-icon {
    font-size: 0.8em;
    margin-top: 2px;
}

.calendar-day.other-month {
    opacity: 0.3;
    cursor: default;
}

.stats-container {
    display: flex;
    gap: 15px;
    justify-content: space-between;
}

.stat-item {
    flex: 1;
    background: white;
    padding: 20px;
    border-radius: 15px;
    text-align: center;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.stat-label {
    display: block;
    font-size: 0.9em;
    color: #666;
    margin-bottom: 5px;
}

.stat-value {
    display: block;
    font-size: 1.8em;
    font-weight: 700;
    color: #4CAF50;
}

.toast {
    position: fixed;
    top: 20px;
    right: 20px;
    background: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 15px 20px;
    border-radius: 10px;
    transform: translateX(400px);
    transition: transform 0.3s ease;
    z-index: 1000;
    max-width: 300px;
}

.toast.show {
    transform: translateX(0);
}

@media (max-width: 480px) {
    .container {
        padding: 10px;
    }

    .header h1 {
        font-size: 2em;
    }

    .month-navigation {
        padding: 8px 15px;
    }

    .nav-btn {
        width: 35px;
        height: 35px;
    }

    .calendar-container {
        padding: 15px;
    }

    .calendar-grid {
        gap: 5px;
    }
}