:root {
    --bg-color: #ffffff;
    --text-color: #333333;
    --timer-color: #333333;
    --container-bg: #ffffff;
}

[data-theme="dark"] {
    --bg-color: #333333;
    --text-color: #ffffff;
    --timer-color: #333333;
    --container-bg: #ffffff;
}

body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
}

.container {
    text-align: center;
    background-color: var(--container-bg);
    padding: 20px 30px;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    margin: 0 20px;
}

.timer {
    font-size: 4rem;
    font-weight: bold;
    margin: 2rem 0;
    color: var(--timer-color);
}

.controls button {
    font-size: 1.1rem;
    margin: 0 0.5rem;
    padding: 0.5rem 1rem;
    cursor: pointer;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 5px;
}

.controls button:hover {
    background-color: #45a049;
}

.mode {
    margin-top: 1rem;
    font-size: 1.2rem;
    color: #666;
}

#toggle-mode {
    margin-top: 1rem;
    background-color: #2196F3;
}

#toggle-mode:hover {
    background-color: #1976D2;
}

.theme-switch {
    position: fixed;
    top: 1rem;
    right: 1rem;
    display: flex;
    gap: 0.5rem;
    z-index: 1000;
}

.theme-button {
    background: none;
    border: none;
    padding: 0.5rem;
    cursor: pointer;
    border-radius: 50%;
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
}

.theme-button:hover {
    background-color: rgba(128, 128, 128, 0.2);
}

.theme-button.active {
    background-color: rgba(128, 128, 128, 0.3);
}

h1 {
    color: var(--timer-color);
}

.task-input {
    position: relative;
    margin-bottom: 2rem;
}

#task-input {
    width: 100%;
    padding: 0.5rem;
    font-size: 1.5rem;
    border: none;
    border-bottom: 2px solid #ccc;
    background: transparent;
    color: var(--timer-color);
    text-align: center;
}

#task-input:focus {
    outline: none;
    border-bottom-color: #666;
}

.controls {
    margin-bottom: 1rem;
}

@media (max-width: 480px) {
    .container {
        padding: 20px 40px;
        margin: 0 30px;
    }
}