:root {
    --bg: #ffffff; --text: #1a1a1a; --card: #f3f4f6; --accent: #3b82f6;
}
.dark-theme {
    --bg: #111827; --text: #f9fafb; --card: #1f2937; --accent: #60a5fa;
}

body { background: var(--bg); color: var(--text); font-family: sans-serif; transition: 0.3s; margin: 0; }
.container { max-width: 500px; margin: 0 auto; padding: 20px; text-align: center; }
header { display: flex; justify-content: space-between; align-items: center; border-bottom: 2px solid var(--card); }
h1 { letter-spacing: -2px; font-size: 2.5rem; }

.word-display h2 { font-size: 3rem; margin: 10px 0; color: var(--accent); }
.options-grid { display: grid; gap: 10px; margin-top: 20px; }
.option-btn { background: var(--card); border: 2px solid transparent; color: var(--text); padding: 15px; border-radius: 12px; cursor: pointer; text-align: left; font-size: 1rem; }
.option-btn:hover { border-color: var(--accent); }

.overlay { position: fixed; inset: 0; background: rgba(0,0,0,0.9); display: flex; align-items: center; justify-content: center; z-index: 100; }
.ad-box { background: white; padding: 20px; border-radius: 15px; color: black; }
.ad-placeholder { width: 300px; height: 250px; background: #ddd; margin: 10px 0; display: flex; align-items: center; justify-content: center; }
.hidden { display: none; }