body {
    font-family: 'Roboto', Arial, sans-serif;
    text-align: center;
    background: radial-gradient(circle, #1e2a38, #0f1419); /* Original dark gradient */
    color: #d9e2ec;
    padding: 20px;
    margin: 0;
    min-height: 100vh;
    transition: background 0.3s ease;
}

.container {
    max-width: 90%;
    width: 700px;
    margin: 0 auto;
    background: #2a3542; /* Original container */
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
    transition: transform 0.3s ease, background 0.3s ease;
}

.container:hover {
    transform: translateY(-2px);
}

h2 {
    font-family: 'Montserrat', sans-serif;
    font-weight: 700;
    font-size: clamp(24px, 5vw, 32px);
    color: #4a90e2; /* Original blue */
    margin-bottom: 5px;
}

.tagline {
    font-size: clamp(14px, 3vw, 16px);
    color: #a0b1c5; /* Original tagline */
    margin-bottom: 15px;
    font-style: italic;
}

.input-box {
    width: 100%;
    padding: 12px;
    font-size: clamp(14px, 3vw, 16px);
    border: 1px solid #3a4655; /* Original border */
    border-radius: 8px;
    background: #1e2a38; /* Original input */
    color: #d9e2ec;
    margin-bottom: 15px;
    box-sizing: border-box;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.input-box:focus {
    border-color: #4a90e2; /* Original blue */
    box-shadow: 0 0 5px rgba(74, 144, 226, 0.4);
    outline: none;
}

.button {
    background: #4a90e2; /* Original button */
    color: #fff;
    padding: 12px 25px;
    border: none;
    cursor: pointer;
    font-size: clamp(14px, 3vw, 16px);
    margin: 5px;
    border-radius: 8px;
    transition: background 0.3s ease, transform 0.2s ease;
}

.button:hover {
    background: #357abd; /* Original hover */
    transform: scale(1.05);
}

.button:active {
    transform: scale(0.98);
}

.example-button {
    background: #5f6a7d; /* Original example button */
    padding: 10px 15px;
    font-size: clamp(12px, 2.5vw, 14px);
    border-radius: 8px;
}

.example-button:hover {
    background: #4a5363; /* Original hover */
}

.result {
    margin-top: 20px;
    padding: 20px;
    background: #1e2a38; /* Original result */
    border-radius: 8px;
    text-align: left;
    font-size: clamp(14px, 3vw, 16px);
    line-height: 2;
    border: 1px solid #3a4655;
    transition: background 0.3s ease;
}

.result:hover {
    background: #263340; /* Original hover */
}

.result p {
    margin: 15px 0;
    padding: 10px;
    background: #2a3542;
    border-radius: 5px;
}

.result strong {
    display: block;
    margin-bottom: 5px;
    color: #4a90e2; /* Original blue */
}

.result em {
    font-style: italic;
    color: #a0b1c5; /* Original gray */
    font-size: clamp(12px, 2.5vw, 14px);
}

.instructions {
    text-align: left;
    background: #1e2a38; /* Original instructions */
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: clamp(12px, 2.5vw, 14px);
    border: 1px solid #3a4655;
}

.instructions ul {
    margin: 10px 0;
    padding-left: 20px;
}

.banner-ad {
    margin-top: 20px;
    padding: 15px;
    background: #3a4655; /* Original ad */
    border-radius: 8px;
    text-align: center;
    font-size: clamp(12px, 2.5vw, 14px);
}

.interstitial-ad {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8); /* Original overlay */
    z-index: 1000;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    color: #fff;
    font-size: clamp(16px, 4vw, 18px);
}

.interstitial-ad button {
    margin-top: 20px;
    padding: 10px 20px;
    background: #e74c3c; /* Original red */
    border: none;
    border-radius: 5px;
    color: #fff;
    cursor: pointer;
    font-size: clamp(14px, 3vw, 16px);
}

.interstitial-ad button:hover {
    background: #c0392b; /* Original hover */
}

.popup {
    display: none;
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: #2a3542; /* Original popup */
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    z-index: 2000;
    color: #d9e2ec;
    width: 90%;
    max-width: 500px;
    max-height: 80%;
    overflow-y: auto;
}

.popup button {
    margin: 10px;
}

.kid-friendly {
    background: radial-gradient(circle, #ffeb3b, #ff9800); /* Original kid-friendly gradient */
    color: #333;
}

.kid-friendly .container {
    background: #fff;
    border: 2px solid #2196f3; /* Original blue */
}

.kid-friendly .tagline {
    color: #e91e63; /* Original pink */
    font-size: clamp(16px, 3.5vw, 18px);
}

.kid-friendly .input-box {
    background: #f0f0f0;
    color: #333;
    border: 2px solid #2196f3;
}

.kid-friendly .result,
.kid-friendly .instructions {
    background: #f9f9f9;
    border: 2px solid #2196f3;
    color: #333;
}

.kid-friendly .result p {
    background: #fff;
}

.kid-friendly .result strong {
    color: #2196f3;
}

.kid-friendly .result em {
    color: #e91e63;
}

.kid-friendly .banner-ad {
    background: #ffeb3b;
    color: #333;
}

/* Fraction Styling */
.fraction {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    vertical-align: middle;
    font-size: 18px;
    margin: 0 8px;
    padding: 4px;
}

.fraction .numerator {
    display: block;
    padding-bottom: 4px;
    border-bottom: 2px solid #d9e2ec;
    margin-bottom: 4px;
    min-width: 20px;
    text-align: center;
}

.fraction .denominator {
    display: block;
    padding-top: 4px;
    min-width: 20px;
    text-align: center;
}

.kid-friendly .fraction .numerator {
    border-bottom: 2px solid #333;
}

/* Visual Cues */
.highlight {
    font-weight: bold;
}

/* Tooltips */
.tooltip {
    position: relative;
    cursor: help;
}

.tooltip::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background: #1e2a38;
    color: #d9e2ec;
    padding: 8px;
    border-radius: 4px;
    font-size: 12px;
    white-space: nowrap;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.2s ease;
    z-index: 10;
}

.tooltip:hover::after {
    opacity: 1;
}

@media (max-width: 600px) {
    .container {
        padding: 15px;
    }
    .button {
        padding: 10px 20px;
        margin: 5px 2px;
    }
    .example-button {
        padding: 8px 10px;
    }
    .result {
        padding: 15px;
    }
    .instructions {
        padding: 10px;
    }
    .input-box {
        font-size: clamp(12px, 3vw, 14px);
    }
}