:root {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --container-bg: #1e1e1e;
    --border-color: #444;
    --active-border-color: #3e9cff;
    --active-bg-color: #2a3a4a;
    --correct-bg: #28a745;
    --incorrect-bg: #dc3545;
    --key-bg: #333;
    --key-hover-bg: #444;
    --button-bg: #333;
    --button-hover-bg: #444;
}

body.light-mode {
    --bg-color: #f0f0f0;
    --text-color: #333;
    --container-bg: #ffffff;
    --border-color: #ccc;
    --active-border-color: #007bff;
    --active-bg-color: #e6f2ff;
    --key-bg: #fff;
    --key-hover-bg: #e9e9e9;
    --button-bg: #e9e9e9;
    --button-hover-bg: #dcdcdc;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
    padding: 20px 0;
}

.main-container {
    background-color: var(--container-bg);
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    text-align: center;
    max-width: 95%;
    border: 1px solid var(--border-color);
}

#themeToggle {
    position: absolute;
    top: 15px;
    right: 15px;
    font-size: 1.5rem;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-color);
}

h1 { margin-top: 0; }
.subtitle { margin-bottom: 10px; max-width: 500px; margin-left: auto; margin-right: auto; line-height: 1.5;}
#timer { font-size: 2em; margin: 10px 0 20px 0; color: var(--active-border-color); }

.controls {
    margin-bottom: 20px;
    display: flex;
    justify-content: center;
    gap: 10px;
    flex-wrap: wrap;
}

#levelToggle,
#revealButton {
    padding: 8px 16px;
    font-size: 1rem;
    cursor: pointer;
    background-color: var(--button-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-radius: 5px;
    transition: background-color 0.2s;
}

#levelToggle:hover,
#revealButton:hover {
    background-color: var(--button-hover-bg);
}


#grid-container {
    display: grid;
    grid-template-columns: repeat(10, 40px);
    grid-template-rows: repeat(10, 40px);
    gap: 2px;
    margin-bottom: 20px;
}

.grid-cell {
    width: 40px;
    height: 40px;
    border: 1px solid var(--border-color);
    background-color: var(--container-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2em;
    font-weight: bold;
    user-select: none;
    transition: background-color 0.3s, border-color 0.3s;
}

.grid-cell.active {
    border: 2px solid var(--active-border-color);
    background-color: var(--active-bg-color);
}

.grid-cell.correct { background-color: var(--correct-bg); color: white; border-color: var(--correct-bg);}
.grid-cell.incorrect { background-color: var(--incorrect-bg); color: white; border-color: var(--incorrect-bg);}

#keyboard { display: flex; flex-direction: column; gap: 5px; }
.row { display: flex; justify-content: center; gap: 5px; }

.key {
    width: 60px;
    height: 60px;
    font-size: 1.5em;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    background-color: var(--key-bg);
    color: var(--text-color);
    cursor: pointer;
    transition: background-color 0.2s;
}

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

@media (max-width: 500px) {
    .main-container { padding: 10px; }
    #grid-container {
        grid-template-columns: repeat(10, 8vw);
        grid-template-rows: repeat(10, 8vw);
    }
    .grid-cell { width: 8vw; height: 8vw; font-size: 1em; }
    .key { width: 15vw; height: 15vw; max-width: 60px; max-height: 60px; }
    h1 { font-size: 1.5em; }
    #timer { font-size: 1.8em; }
}