:root { /* Default Dark Theme */
    --primary-color: #bb86fc;
    --primary-variant: #3700b3;
    --secondary-color: #03dac6;
    --background-color: #121212;
    --surface-color: #1e1e1e;
    --on-surface-color: #e1e1e1;
    --on-primary-color: #000;
    --calendar-header-bg: #252525;
    --calendar-grid-border: #2c2c2c;
    --not-current-month-bg: #1a1a1a;
    --not-current-month-color: #555;
    --hover-bg: #2a2a2a;
    --modal-overlay-bg: rgba(0, 0, 0, 0.7);
    --modal-shadow: 0 5px 15px rgba(0,0,0,0.3);
    --modal-input-bg: #2c2c2c;
    --modal-input-border: #444;
    --delete-button-bg: #cf6679;
    --cancel-button-bg: #444;
}

body[data-theme="light"] {
    --primary-color: #6200ee;
    --primary-variant: #3700b3;
    --secondary-color: #03dac6;
    --background-color: #ffffff;
    --surface-color: #f5f5f5;
    --on-surface-color: #333333;
    --on-primary-color: #ffffff;
    --calendar-header-bg: #e0e0e0;
    --calendar-grid-border: #cccccc;
    --not-current-month-bg: #eeeeee;
    --not-current-month-color: #aaaaaa;
    --hover-bg: #e5e5e5;
    --modal-overlay-bg: rgba(0, 0, 0, 0.5);
    --modal-shadow: 0 5px 15px rgba(0,0,0,0.2);
    --modal-input-bg: #ffffff;
    --modal-input-border: #bbbbbb;
    --delete-button-bg: #e53935;
    --cancel-button-bg: #9e9e9e;
}

body {
    font-family: 'Roboto', sans-serif;
    background-color: var(--background-color);
    color: var(--on-surface-color);
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    height: 100vh;
}

#app {
    width: 100%;
    max-width: 900px;
    background-color: var(--surface-color);
    border-radius: 12px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);
    overflow: hidden;
}

.calendar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 30px;
    background-color: var(--calendar-header-bg);
}

.calendar-header h2 {
    margin: 0;
    font-weight: 500;
    font-size: 1.5em;
}

.nav-button {
    background: none;
    border: none;
    color: var(--on-surface-color);
    font-size: 2em;
    cursor: pointer;
    transition: color 0.3s;
}

.nav-button:hover {
    color: var(--primary-color);
}

.theme-toggle-button {
    background: none;
    border: none;
    color: var(--on-surface-color);
    font-size: 1.5em;
    cursor: pointer;
    transition: color 0.3s;
    margin: 0 10px; /* Add some margin */
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle-button:hover {
    color: var(--primary-color);
}

.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 1px;
    background-color: var(--calendar-grid-border);
}

.day-header {
    text-align: center;
    padding: 10px 0;
    font-weight: bold;
    background-color: var(--calendar-header-bg);
}

.day-cell {
    position: relative;
    min-height: 100px;
    padding: 8px;
    background-color: var(--surface-color);
    cursor: pointer;
    transition: background-color 0.3s;
}

.day-cell:hover {
    background-color: var(--hover-bg);
}

.day-cell.not-current-month {
    color: var(--not-current-month-color);
    background-color: var(--not-current-month-bg);
}

.day-number {
    font-size: 0.9em;
}

.day-cell.today .day-number {
    color: var(--secondary-color);
    font-weight: bold;
}

.note-indicator {
    position: absolute;
    bottom: 8px;
    left: 8px;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background-color: var(--primary-color);
}

.day-cell .todo-item {
    font-size: 0.8em;
    margin-top: 5px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    background-color: var(--primary-variant);
    color: var(--on-primary-color); /* Changed from on-surface-color for better contrast */
    padding: 2px 4px;
    border-radius: 4px;
}

#note-modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: var(--modal-overlay-bg);
    justify-content: center;
    align-items: center;
}

#note-modal.show {
    display: flex;
}

.modal-content {
    background-color: var(--modal-bg);
    padding: 30px;
    border-radius: 8px;
    width: 90%;
    max-width: 500px;
    box-shadow: var(--modal-shadow);
}

.modal-content h3 {
    margin-top: 0;
    color: var(--on-surface-color);
}

#note-textarea {
    width: 100%;
    height: 150px;
    margin-top: 15px;
    background-color: var(--modal-input-bg);
    border: 1px solid var(--modal-input-border);
    color: var(--on-surface-color);
    border-radius: 4px;
    padding: 10px;
}

.modal-buttons {
    margin-top: 20px;
    display: flex;
    justify-content: flex-end;
    gap: 10px;
}

.modal-button {
    padding: 10px 20px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-weight: bold;
    color: var(--on-primary-color);
}

.save-button {
    background-color: var(--primary-color);
}

.delete-button {
    background-color: var(--delete-button-bg);
}

.cancel-button {
    background-color: var(--cancel-button-bg);
}