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

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;
    padding: 20px;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 30px;
    text-align: center;
}

header h1 {
    font-size: 2em;
    margin-bottom: 15px;
}

.nav {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px;
}

.nav button {
    background: rgba(255, 255, 255, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.5);
    color: white;
    padding: 8px 16px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.3s;
}

.nav button:hover {
    background: rgba(255, 255, 255, 0.3);
}

#current-month {
    font-size: 1.2em;
    font-weight: bold;
}

.calendar {
    padding: 20px;
}

.weekdays {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 5px;
    margin-bottom: 10px;
}

.weekdays div {
    text-align: center;
    padding: 10px;
    font-weight: bold;
    color: #666;
}

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

.day {
    aspect-ratio: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s;
    background: #f5f5f5;
    min-height: 80px;
}

.day:hover {
    background: #e0e0e0;
    transform: scale(1.05);
}

.day.other-month {
    opacity: 0.3;
}

.day.today {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.day.has-content {
    background: #e8f5e9;
    border: 2px solid #4caf50;
}

.day-number {
    font-size: 1.2em;
    font-weight: bold;
}

.day-summary {
    font-size: 0.6em;
    color: #666;
    margin-top: 4px;
    text-align: center;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    max-width: 90%;
}

.day.has-content .day-summary {
    color: #2e7d32;
}

.content {
    padding: 30px;
    line-height: 1.8;
}

.content h2 {
    color: #667eea;
    margin-bottom: 20px;
    border-bottom: 2px solid #667eea;
    padding-bottom: 10px;
}

.content ul {
    list-style: none;
    padding: 0;
}

.content li {
    padding: 10px 15px;
    margin: 5px 0;
    background: #f5f5f5;
    border-radius: 8px;
    border-left: 4px solid #667eea;
}

.content li:hover {
    background: #e8eaf6;
}

.back-btn {
    display: inline-block;
    margin-top: 15px;
    padding: 10px 20px;
    background: rgba(255, 255, 255, 0.2);
    color: white;
    text-decoration: none;
    border-radius: 8px;
    transition: all 0.3s;
}

.back-btn:hover {
    background: rgba(255, 255, 255, 0.3);
}

footer {
    background: #f5f5f5;
    padding: 20px;
    text-align: center;
    color: #666;
}

footer a {
    color: #667eea;
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

@media (max-width: 600px) {
    .day {
        min-height: 50px;
    }
    
    .day-number {
        font-size: 0.9em;
    }
    
    .day-summary {
        display: none;
    }
}