body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f9;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
}

.container {
    text-align: center;
    background-color: #fff;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    max-width: 500px;
    width: 90%;
}

h1 {
    color: #333;
}

.timer {
    margin: 20px 0;
}

#timer-display {
    font-size: 48px;
    font-weight: bold;
    color: #333;
}

#session-type {
    font-size: 24px;
    color: #666;
    margin: 10px 0;
}

.controls {
    display: flex;
    justify-content: center;
    gap: 10px;
}

button {
    padding: 10px 20px;
    font-size: 16px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s;
}

#start-stop-btn {
    background-color: #28a745;
    color: #fff;
}

#start-stop-btn.stop {
    background-color: #dc3545;
}

#reset-btn {
    background-color: #007bff;
    color: #fff;
}

#switch-mode-btn {
    background-color: #ffc107;
    color: #333;
}

button:hover {
    opacity: 0.9;
}

.study-log {
    margin-top: 20px;
}

#log-note {
    width: 100%;
    height: 80px;
    margin: 10px 0;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
    resize: none;
}

#add-log-btn {
    background-color: #17a2b8;
    color: #fff;
}

#log-entries {
    text-align: left;
    max-height: 200px;
    overflow-y: auto;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
}

.log-entry {
    margin: 10px 0;
    padding: 10px;
    background-color: #f8f9fa;
    border-radius: 5px;
}

.work-mode {
    background-color: #e6ffed;
}

.break-mode {
    background-color: #fff3e6;
}