:root {
    --primary-color: #3498db;
    --secondary-color: #2c3e50;
    --background-color: #f4f7f9;
    --card-background: #ffffff;
    --border-color: #e0e0e0;
    --text-color: #333;
    --light-text-color: #95a5a6;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    margin: 0;
    padding: 20px;
}

.container {
    max-width: 900px;
    margin: 20px auto;
    background-color: var(--card-background);
    padding: 20px 40px;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.08);
}

header {
    text-align: center;
    margin-bottom: 30px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--border-color);
}

h1, h2 {
    color: var(--secondary-color);
    margin: 0;
}

h1 {
    font-size: 2.2em;
}

h2 {
    font-size: 1.2em;
    margin-top: 5px;
    font-weight: normal;
}

.controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
    background-color: #f8f9fa;
    padding: 15px;
    border-radius: 8px;
    border: 1px solid #e9ecef;
}

.controls label {
    font-weight: bold;
    color: var(--secondary-color);
}

#monthSelect {
    padding: 8px 12px;
    border-radius: 5px;
    border: 1px solid var(--border-color);
    background-color: var(--card-background);
    cursor: pointer;
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    background-image: url('data:image/svg+xml;utf8,<svg fill="%232c3e50" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path d="M7 10l5 5 5-5z"/></svg>');
    background-repeat: no-repeat;
    background-position: right 10px center;
    background-size: 12px;
}

#totalPointsDisplay {
    font-size: 1.5em;
    font-weight: bold;
    color: var(--primary-color);
}

h3 {
    background-color: #ecf0f1;
    padding: 10px 15px;
    border-radius: 5px;
    margin-top: 40px;
    border-left: 5px solid var(--primary-color);
}

ul {
    list-style-type: none;
    padding-left: 0;
    margin-top: 0;
}

li {
    padding: 12px 5px;
    border-bottom: 1px solid #eee;
    transition: background-color 0.2s ease;
}

li:hover {
    background-color: #fafafa;
}

li:last-child {
    border-bottom: none;
}

.task-item {
    display: flex;
    align-items: center;
}

input[type="checkbox"] {
    margin-right: 15px;
    width: 20px;
    height: 20px;
    flex-shrink: 0;
    cursor: pointer;
}

.task-item span {
    transition: color 0.3s ease, text-decoration 0.3s ease;
}

.task-item input:checked + span {
    text-decoration: line-through;
    color: var(--light-text-color);
}

strong {
    color: var(--primary-color);
}

.sub-tasks {
    padding-left: 40px;
    margin-top: 10px;
    border-left: 2px solid var(--border-color);
}

.sub-tasks li {
    font-size: 0.9em;
    padding: 8px 5px;
}

.main-task-title {
    font-weight: bold;
}

.footer {
    text-align: center;
    margin-top: 40px;
    font-size: 0.8em;
    color: var(--light-text-color);
}

.total-points-container {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    margin-top: 20px;
    padding: 15px 25px;
    background-color: #e8f5e9;
    border: 1px solid #c8e6c9;
    border-radius: 8px;
    font-weight: bold;
    color: #2e7d32;
}

.total-points-container strong {
    font-size: 1.8em;
    color: #1b5e20;
    margin-left: 10px;
}