* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #0f172a, #1e293b);
    color: #f1f5f9;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 1.25rem;
}

body > div {
    background: #1e293b;
    border-radius: 1.25rem;
    padding: 2.5rem;
    box-shadow: 0 0.9375rem 2.1875rem rgba(0, 0, 0, 0.4);
    max-width: 31.25rem;
    width: 100%;
}

input[type="number"] {
    width: 100%;
    padding: 0.9375rem 1.25rem;
    margin-bottom: 1.25rem;
    border: 0.125rem solid #334155;
    border-radius: 0.75rem;
    background: #0f172a;
    color: #f1f5f9;
    font-size: 1.125rem;
    transition: all 0.3s ease;
}

input[type="number"]:focus {
    outline: none;
    border-color: #7c3aed;
    transform: translateY(-0.125rem);
    box-shadow: 0 0.3125rem 0.9375rem rgba(124, 58, 237, 0.3);
}

input[type="number"]::placeholder {
    color: #64748b;
}

.operations {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.75rem;
    margin-bottom: 1.5625rem;
}

button {
    padding: 0.9375rem 1.25rem;
    border: none;
    border-radius: 0.75rem;
    font-size: 1.125rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    background: #334155;
    color: #f1f5f9;
}

button:hover {
    transform: translateY(-0.1875rem);
    box-shadow: 0 0.5rem 1.25rem rgba(0, 0, 0, 0.3);
}

button:active {
    transform: translateY(-0.0625rem);
}

#plus {
    background: linear-gradient(135deg, #06d6a0, #059669);
}

#plus:hover {
    background: linear-gradient(135deg, #059669, #047857);
}

#minus {
    background: linear-gradient(135deg, #3b82f6, #2563eb);
}

#minus:hover {
    background: linear-gradient(135deg, #2563eb, #1d4ed8);
}

#multiply {
    background: linear-gradient(135deg, #f59e0b, #d97706);
}

#multiply:hover {
    background: linear-gradient(135deg, #d97706, #b45309);
}

#share {
    background: linear-gradient(135deg, #ef4444, #dc2626);
}

#share:hover {
    background: linear-gradient(135deg, #dc2626, #b91c1c);
}

#submit {
    width: 100%;
    background: linear-gradient(135deg, #7c3aed, #6d28d9);
    color: white;
    font-size: 1.25rem;
    padding: 1.125rem;
    margin-bottom: 1.875rem;
}

#submit:hover {
    background: linear-gradient(135deg, #6d28d9, #5b21b6);
}

.result-section {
    background: #0f172a;
    padding: 1.5625rem;
    border-radius: 0.9375rem;
    border-left: 0.25rem solid #7c3aed;
}

h4 {
    color: #94a3b8;
    font-size: 1rem;
    margin-bottom: 0.625rem;
    text-transform: uppercase;
    letter-spacing: 0.0625rem;
}

#result {
    font-size: 2rem;
    font-weight: bold;
    background: linear-gradient(45deg, #7c3aed, #06d6a0);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-align: center;
    min-height: 3rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* Анимация появления результата */
@keyframes resultAppear {
    0% {
        opacity: 0;
        transform: scale(0.8);
    }
    100% {
        opacity: 1;
        transform: scale(1);
    }
}

.result-animation {
    animation: resultAppear 0.5s ease-out;
}

/* Адаптивность */
@media (max-width: 37.5rem) {
    body {
        padding: 0.9375rem;
    }
    
    body > div {
        padding: 1.5625rem;
    }
    
    .operations {
        grid-template-columns: repeat(2, 1fr);
        gap: 0.625rem;
    }
    
    input[type="number"], button {
        padding: 0.75rem 0.9375rem;
        font-size: 1rem;
    }
    
    #result {
        font-size: 1.75rem;
    }
}

/* Стили для disabled кнопок */
button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

button:disabled:hover {
    transform: none !important;
    box-shadow: none !important;
}