:root {
    --color-primary: #2a9df4;
    --color-primary-light: #e6f4ff;
    --color-secondary: #28a745;
    --color-secondary-light: #dff6e4;
    --color-bg: #ffffff;
    --color-text: #333333;
    --color-border: #dddddd;
    --color-danger: #dc3545;
    --color-danger-light: #ffeaea;

    --font-family-base: 'Arial', sans-serif;
    --font-size-base: 16px;
    --font-weight-regular: 400;
    --font-weight-bold: 700;

    --spacing-unit: 8px;
    --border-radius: 4px;
}

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

body {
    font-family: var(--font-family-base);
    font-size: var(--font-size-base);
    color: var(--color-text);
    background: var(--color-bg);
    line-height: 1.5;
}

#app {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    width: 240px;
    background: var(--color-primary-light);
    padding: var(--spacing-unit);
    border-right: 1px solid var(--color-border);
}

.sidebar .app-title {
    font-size: 1.5em;
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-unit);
    color: var(--color-primary);
}

.sidebar nav ul {
    list-style: none;
}

.sidebar nav ul li {
    margin-bottom: var(--spacing-unit);
}

.sidebar input[type="checkbox"] {
    margin-right: var(--spacing-unit);
}

main {
    flex-grow: 1;
    padding: var(--spacing-unit) 2 * var(--spacing-unit);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-unit);
}

header {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-unit);
}

header h2 {
    font-size: 1.25em;
    color: var(--color-primary);
}

.filters {
    display: flex;
    align-items: center;
}

.filters label {
    margin-right: var(--spacing-unit);
}

button.generate-schedule {
    background: var(--color-secondary);
    color: var(--color-bg);
    border: none;
    padding: var(--spacing-unit) 2 * var(--spacing-unit);
    border-radius: var(--border-radius);
    font-weight: var(--font-weight-bold);
    cursor: pointer;
    transition: background 0.3s, color 0.3s;
    outline: none;
}

button.generate-schedule:hover {
    background: var(--color-secondary-light);
    color: var(--color-secondary);
}

button.generate-schedule:focus {
    box-shadow: 0 0 3px 2px rgba(40, 167, 69, 0.5);
}

.permission-matrix {
    width: 100%;
    border-collapse: collapse;
    margin-top: var(--spacing-unit);
    text-align: center;
    font-size: 0.875em;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.permission-matrix thead tr {
    background: var(--color-primary);
    color: var(--color-bg);
}

.permission-matrix th, .permission-matrix td {
    border: 1px solid var(--color-border);
    padding: var(--spacing-unit);
    transition: background-color 0.3s, color 0.3s;
}

.permission-matrix tbody tr:nth-child(odd) {
    background: var(--color-primary-light);
}

.permission-matrix tbody tr:nth-child(even) {
    background: var(--color-bg);
}

.permission-matrix td.assigned:hover,
.permission-matrix td.unassigned:hover {
    transform: scale(1.02);
}

.permission-matrix td.assigned {
    background-color: var(--color-secondary-light);
    color: var(--color-secondary);
    font-weight: var(--font-weight-bold);
}

.permission-matrix td.unassigned {
    background-color: var(--color-danger-light);
    color: var(--color-danger);
    font-weight: var(--font-weight-bold);
}

.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.modal-content {
    background: var(--color-bg);
    padding: 2 * var(--spacing-unit);
    border-radius: var(--border-radius);
    width: 90%;
    max-width: 600px;
    box-shadow: 0px 4px 8px rgba(0, 0, 0, 0.2);
    position: relative;
}

.modal-content h3 {
    margin-bottom: var(--spacing-unit);
    color: var(--color-primary);
}

#close-modal {
    position: absolute;
    top: var(--spacing-unit);
    right: var(--spacing-unit);
    cursor: pointer;
    font-size: 1.5rem;
    color: var(--color-danger);
}

.modal.hidden {
    display: none;
}

.modal:not(.hidden) {
    display: flex;
}

.modal-content:focus-within {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

@media screen and (max-width: 768px) {
    .sidebar {
        width: 100px;
    }

    main {
        padding: var(--spacing-unit);
    }

    button.generate-schedule {
        width: 100%;
    }
}