body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

h1, h3 {
    margin: 0 0 10px 0;
    letter-spacing: 1px;
    font-weight: 700;
}

h3 {
    font-size: 0.9em;
    color: black;
}

input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
    vertical-align: middle;
}

input[type="text"] {
    font-family: Arial, sans-serif;
    font-size: 0.9em;
    border: none;
    border-bottom: 2px solid #eee;
    padding: 2px;
}
input[type="text"]:focus {
    outline: none;
    border-color: #ccc;
}

.planner {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: auto repeat(4, 1fr);
    grid-column-gap: 0px;
    grid-row-gap: 0px;
    width: 1200px;
    height: 800px;
    background-color: #fff;
    border: 3px solid black;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
}

.plan-header {
    grid-area: 1 / 1 / 2 / 5;
    border-bottom: 3px solid black;
}
.plan-sidebar {
    grid-area: 2 / 1 / 6 / 2;
    border-right: 3px solid black;
}

.monday     { grid-area: 2 / 2 / 4 / 3; }
.tuesday    { grid-area: 2 / 3 / 4 / 4; }
.wednesday  { grid-area: 2 / 4 / 4 / 5; }
.thursday   { grid-area: 4 / 2 / 6 / 3; }
.friday     { grid-area: 4 / 3 / 6 / 4; }
.saturday   { grid-area: 4 / 4 / 5 / 5; }
.sunday     { grid-area: 5 / 4 / 6 / 5; }

.plan-header, .plan-sidebar, .weekday, .weekend {
    padding: 15px;
    box-sizing: border-box;
}

.weekday, .weekend {
    display: flex;
    flex-direction: column;
}

.monday, .tuesday, .thursday, .friday {
    border-right: 1px solid #ccc;
}
.monday, .tuesday, .wednesday {
    border-bottom: 1px solid #ccc;
}
.saturday {
    border-bottom: 1px solid #ccc;
}

.plan-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.plan-title {
    font-size: 2.5em;
    margin: 0;
}
.header-field {
    font-size: 0.8em;
    color: black;
    display: flex;
    align-items: center;
}

.header-field.small {
    flex-direction: column;
    align-items: flex-start;
    gap: 5px;
}

.header-field input[type="text"] {
    width: 150px;
    margin-left: 10px;
    font-size: 1.1em;
    border-bottom: 1px solid #999;
}

.header-field input {
    margin-left: 10px;
}

.plan-sidebar {
    overflow-y: auto;
}
.task-list {
    list-style-type: none;
    padding-left: 0;
    margin-bottom: 20px;
}
.task-list li {
    display: flex;
    align-items: center;
    margin-bottom: 12px;
}

.task-list input[type="text"] {
    flex-grow: 1;
    height: 20px;
    margin-left: 10px;
    cursor: text;
    transition: border-color 0.2s;
    border-bottom: 2px solid #eee;
}

.task-list input[type="text"]:focus {
    border-color: #ccc;
    outline: none;
}

.day-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
}
.day-header h3 {
    margin: 0;
    font-size: 1.1em;
    color: black;
}

.day-input {
    flex-grow: 1;
    width: 100%;
    border: none;
    background: transparent;
    outline: none;
    resize: none;
    font-family: Arial, sans-serif;
    font-size: 1em;
    padding: 0;
    margin-top: 10px;
}