:root {
    --duolingo-green: #58cc02;
    --duolingo-dark-green: #46a302;
    --background: #1f1f1f;
    --card-bg: #2d2d2d;
    --text: #ffffff;
    --input-bg: #3d3d3d;
    --error: #ff4b4b;
    --hint-color: #ffd900;
    --disabled: #666666;
}

input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

input[type="number"] {
    -moz-appearance: textfield;
}

body {
    font-family: 'Din Round', Arial, sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    background-color: var(--background);
    margin: 0;
    padding: 20px;
    color: var(--text);
    min-height: 100vh;
}

.container {
    background-color: var(--card-bg);
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
    text-align: center;
    max-width: 500px;
    width: 100%;
}

h1 {
    color: var(--duolingo-green);
    margin-bottom: 30px;
}

.max-number {
    margin: 20px 0;
    font-size: 18px;
}

.slider {
    -webkit-appearance: none;
    width: 80%;
    height: 8px;
    border-radius: 4px;
    background: var(--input-bg);
    outline: none;
    margin-top: 10px;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--duolingo-green);
    cursor: pointer;
    transition: background 0.2s;
}

.slider::-webkit-slider-thumb:hover {
    background: var(--duolingo-dark-green);
}

.slider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--duolingo-green);
    cursor: pointer;
    border: none;
    transition: background 0.2s;
}

.slider::-moz-range-thumb:hover {
    background: var(--duolingo-dark-green);
}

.problem {
    font-size: 24px;
    margin: 30px 0;
    line-height: 1.5;
}

.inputs {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 15px;
    margin: 30px 0;
}

input {
    width: 80px;
    padding: 12px;
    font-size: 20px;
    border: 2px solid var(--duolingo-green);
    border-radius: 10px;
    text-align: center;
    background-color: var(--input-bg);
    color: var(--text);
    transition: all 0.2s;
}

input:focus {
    outline: none;
    border-color: var(--duolingo-dark-green);
    box-shadow: 0 0 0 3px rgba(88, 204, 2, 0.3);
}

input:disabled {
    border-color: var(--disabled);
    background-color: var(--disabled);
    cursor: not-allowed;
}

.buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-top: 20px;
}

button {
    background-color: var(--duolingo-green);
    color: var(--text);
    border: none;
    padding: 15px 30px;
    font-size: 20px;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.2s;
    font-weight: bold;
    text-transform: uppercase;
}

button:hover:not(:disabled) {
    background-color: var(--duolingo-dark-green);
}

button:disabled {
    background-color: var(--disabled);
    cursor: not-allowed;
}

#hintBtn {
    background-color: var(--hint-color);
    color: #000;
}

#hintBtn:hover:not(:disabled) {
    background-color: #e6c300;
}

#hintBtn:disabled {
    background-color: var(--disabled);
    color: var(--text);
}

.feedback {
    margin-top: 25px;
    font-size: 20px;
    font-weight: bold;
    min-height: 30px;
}

.correct {
    color: var(--duolingo-green);
}

.incorrect {
    color: var(--error);
}

.hint {
    color: var(--hint-color);
}

.score {
    font-size: 24px;
    margin-bottom: 20px;
    color: var(--duolingo-green);
}

.answer-reveal {
    margin-top: 15px;
    font-size: 18px;
    color: #888;
}

.hint-text {
    margin-top: 15px;
    font-size: 18px;
    color: var(--hint-color);
    min-height: 27px;
}