:root {
    --bg-color: #f7f9fc;
    --text-color: #333;
    --container-bg: white;
    --input-border-color: #ccc;
    --button-bg: #4A90E2;
    --button-hover-bg: #357ABD;
    --accent-color: #D9534F;
    --history-user-bg: #E3F2FD;
    --history-gemini-bg: #FCE4EC;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

[data-theme='dark'] {
    --bg-color: #121212;
    --text-color: #E0E0E0;
    --container-bg: #1E1E1E;
    --input-border-color: #444;
    --button-bg: #BB86FC;
    --button-hover-bg: #985EFF;
    --accent-color: #CF6679;
    --history-user-bg: #373737;
    --history-gemini-bg: #402E32;
    --shadow-color: rgba(255, 255, 255, 0.05);
}

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

.container {
    width: 90%;
    max-width: 500px;
    background-color: var(--container-bg);
    padding: 2rem;
    border-radius: 16px;
    box-shadow: 0 8px 32px var(--shadow-color);
    text-align: center;
    transition: background-color 0.3s;
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--button-bg);
    margin-bottom: 1rem;
}

.settings {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.theme-switcher {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

#restart-button, #category-select {
    padding: 0.5rem 1rem;
    border: 1px solid var(--input-border-color);
    border-radius: 8px;
    background-color: transparent;
    color: var(--text-color);
    cursor: pointer;
}

.current-word-display {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
}

#current-word {
    font-weight: 700;
    color: var(--accent-color);
}

.input-area {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

#word-input {
    flex-grow: 1;
    padding: 0.75rem;
    border: 1px solid var(--input-border-color);
    border-radius: 8px;
    font-size: 1rem;
    background-color: var(--bg-color);
    color: var(--text-color);
}

#submit-button {
    padding: 0.75rem 1.5rem;
    background-color: var(--button-bg);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 700;
    transition: background-color 0.3s ease;
}

#submit-button:hover {
    background-color: var(--button-hover-bg);
}

#result {
    font-weight: bold;
    min-height: 1.5rem;
    font-size: 1.1rem;
    margin-top: 1rem;
}

.history-area h2 {
    border-bottom: 2px solid var(--input-border-color);
    padding-bottom: 0.5rem;
}

#word-history {
    list-style: none;
    padding: 0;
    max-height: 200px;
    overflow-y: auto;
}

#word-history li {
    padding: 0.5rem;
    border-radius: 6px;
    margin-bottom: 0.5rem;
}

#word-history li.user {
    background-color: var(--history-user-bg);
}

#word-history li.gemini {
    background-color: var(--history-gemini-bg);
}