:root {
    --bg-color: #ffffff;
    --text-color: #000000;
    --border-color: #ccc;
    --selected-bg: #eee;
    --has-schedule-bg: #d4edda;
    --modal-bg: #fefefe;
    --modal-overlay: rgba(0,0,0,0.4);
    --btn-bg: #f0f0f0;
    --btn-text: #000;
}

body.dark-mode {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --border-color: #444;
    --selected-bg: #333;
    --has-schedule-bg: #1b5e20;
    --modal-bg: #1e1e1e;
    --modal-overlay: rgba(0,0,0,0.7);
    --btn-bg: #333;
    --btn-text: #fff;
}

body {
    font-family: sans-serif;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding: 20px;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
}

#calendar-container {
    width: 400px;
    margin-right: 20px;
}

#calendar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
}

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

.calendar-day {
    text-align: center;
    padding: 10px;
    border: 1px solid var(--border-color);
    cursor: pointer;
}

.calendar-day.selected {
    background-color: var(--selected-bg);
}

#schedule-container {
    width: 300px;
}

#time-slots {
    display: grid;
    grid-template-columns: 1fr;
    gap: 5px;
}

.time-slot {
    padding: 10px;
    border: 1px solid var(--border-color);
    cursor: pointer;
}

.time-slot.has-schedule {
    background-color: var(--has-schedule-bg);
    color: var(--text-color);
}

.modal {
    display: none;
    position: fixed;
    z-index: 1;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: var(--modal-overlay);
}

.modal-content {
    background-color: var(--modal-bg);
    margin: 15% auto;
    padding: 20px;
    border: 1px solid var(--border-color);
    width: 80%;
    max-width: 400px;
    color: var(--text-color);
}

.close-btn {
    color: #aaa;
    float: right;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
}

button {
    background-color: var(--btn-bg);
    color: var(--btn-text);
    border: 1px solid var(--border-color);
    padding: 5px 10px;
    cursor: pointer;
}

textarea {
    width: 100%;
    background-color: var(--modal-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    margin-bottom: 10px;
}

#theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
}