/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --text-color: #333333;
    --text-light: #FFFFFF;
    --card-bg: #FFFFFF;
    --background: #ecf0f1;
    --border-color: #bdc3c7;
    --hover-color: #34495e;
    --today-bg: #3498db;
    --border-radius: 12px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background-color: var(--background);
    color: var(--text-color);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.app-container {
    max-width: 100%;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header styles */
.header {
    background: var(--primary-color);
    color: var(--text-light);
    padding: var(--spacing-lg);
    text-align: center;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    letter-spacing: 1px;
}

/* Main content styles */
.main-content {
    flex: 1;
    padding: var(--spacing-lg);
    display: flex;
    align-items: center;
    justify-content: center;
}

/* Calendar container */
.calendar-container {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    padding: var(--spacing-lg);
    max-width: 600px;
    width: 100%;
    animation: fadeIn 0.5s ease;
}

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

/* Calendar header */
.calendar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--border-color);
}

.calendar-header h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
}

.nav-btn {
    background: var(--secondary-color);
    color: var(--text-light);
    border: none;
    border-radius: 8px;
    width: 40px;
    height: 40px;
    font-size: 1.2rem;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.nav-btn:hover {
    background: var(--hover-color);
    transform: scale(1.1);
}

.nav-btn:active {
    transform: scale(0.95);
}

/* Calendar weekdays */
.calendar-weekdays {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.calendar-weekdays div {
    text-align: center;
    font-weight: 600;
    color: var(--primary-color);
    padding: var(--spacing-sm);
    font-size: 0.9rem;
}

/* Calendar days */
.calendar-days {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: var(--spacing-sm);
}

.calendar-day {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
}

.calendar-day:hover {
    background: var(--background);
    transform: scale(1.05);
}

.calendar-day.other-month {
    color: #bdc3c7;
}

.calendar-day.today {
    background: var(--today-bg);
    color: var(--text-light);
    font-weight: 700;
    box-shadow: 0 4px 12px rgba(52, 152, 219, 0.4);
}

.calendar-day.today:hover {
    background: var(--hover-color);
}

.calendar-day.selected {
    background: var(--accent-color);
    color: var(--text-light);
    font-weight: 600;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .header h1 {
        font-size: 2rem;
    }

    .calendar-container {
        padding: var(--spacing-md);
    }

    .calendar-header h2 {
        font-size: 1.2rem;
    }

    .calendar-weekdays div {
        font-size: 0.8rem;
    }

    .calendar-day {
        font-size: 0.9rem;
    }

    .nav-btn {
        width: 35px;
        height: 35px;
        font-size: 1rem;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 1.5rem;
    }

    .calendar-header h2 {
        font-size: 1rem;
    }

    .calendar-weekdays div {
        font-size: 0.7rem;
        padding: 4px;
    }

    .calendar-day {
        font-size: 0.8rem;
    }

    .nav-btn {
        width: 30px;
        height: 30px;
        font-size: 0.9rem;
    }
}