:root {
    /* Light theme colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f5;
    --text-primary: #333333;
    --text-secondary: #666666;
    --border-color: #e0e0e0;
    --accent-color: #2196f3;
    --hover-color: #1976d2;
    --success-color: #4caf50;
    --warning-color: #ff9800;
    --error-color: #f44336;
}

[data-theme="dark"] {
    --bg-primary: #1e1e1e;
    --bg-secondary: #2d2d2d;
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --border-color: #404040;
    --accent-color: #64b5f6;
    --hover-color: #90caf9;
    --success-color: #81c784;
    --warning-color: #ffb74d;
    --error-color: #e57373;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

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

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--border-color);
}

h1 {
    font-size: 2rem;
    color: var(--text-primary);
}

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

button {
    background-color: var(--accent-color);
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.2s;
}

button:hover {
    background-color: var(--hover-color);
}

.description-section,
.calculator-section,
.results-section,
.settings-section {
    background-color: var(--bg-secondary);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 30px;
    width: 100%;
    min-width: 300px;
}

main {
    width: 100%;
    min-width: 300px;
}

.description-header,
.date-selection-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.collapse-btn {
    background: none;
    border: none;
    color: var(--text-primary);
    cursor: pointer;
    padding: 0 8px;
    font-size: 20px;
    line-height: 1;
    transition: transform 0.3s ease;
}

.collapse-btn[aria-expanded="false"] .collapse-icon {
    display: block;
}

.description-content {
    transition: max-height 0.3s ease-out;
    overflow: hidden;
    max-height: 1000px;
}

.description-content.collapsed {
    max-height: 0;
}

.date-selection-content {
    transition: max-height 0.3s ease-out;
    overflow: hidden;
    max-height: 1000px;
}

.date-selection-content.collapsed {
    max-height: 0;
}

.description-section p {
    margin-bottom: 15px;
    color: var(--text-primary);
}

.description-section ul {
    margin: 15px 0;
    padding-left: 20px;
}

.description-section li {
    margin-bottom: 8px;
    color: var(--text-primary);
}

.description-section li:last-child {
    margin-bottom: 0;
}

.date-inputs {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

input[type="date"],
select {
    padding: 8px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--bg-primary);
    color: var(--text-primary);
}

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

.result-item {
    background-color: var(--bg-primary);
    padding: 15px;
    border-radius: 4px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.result-item .label {
    display: block;
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 5px;
}

.result-item .value {
    font-size: 1.2rem;
    font-weight: bold;
    color: var(--text-primary);
}

.settings-section {
    background-color: var(--bg-secondary);
    border-radius: 8px;
    padding: 20px;
}

.settings-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.region-selection,
.work-pattern-selection {
    padding: 20px;
    background-color: var(--bg-primary);
    border-radius: 4px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.work-pattern {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.custom-pattern {
    display: grid;
    gap: 15px;
}

.day-config {
    display: grid;
    grid-template-columns: 1fr auto;
    align-items: center;
    gap: 15px;
    padding: 10px;
    background-color: var(--bg-primary);
    border-radius: 4px;
}

.day-config label {
    display: flex;
    align-items: center;
    gap: 8px;
}

input[type="number"] {
    width: 70px;
    padding: 5px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--bg-primary);
    color: var(--text-primary);
}

@media (max-width: 768px) {
    .app-container {
        padding: 10px;
    }

    .calculator-section,
    .settings-section {
        padding: 15px;
        min-width: unset;
    }

    main {
        min-width: unset;
    }

    .settings-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .day-config {
        grid-template-columns: 1fr;
        gap: 10px;
    }
}