@import url('https://fonts.googleapis.com/css2?family=Roboto:ital,wght@0,100;0,300;0,400;0,500;0,700;0,900;1,100;1,300;1,400;1,500;1,700;1,900&display=swap');

:root {
    --violet-lightest: #f5f3ff;
    --violet-light: #c4b5fd;
    --violet-medium: #8b5cf6;
    --violet-dark: #6d28d9;
    --violet-darkest: #4c1d95;
}

body {
    font-family: "Roboto", sans-serif;
    margin: 0;
    padding: 0;
    height: 100vh;
    width: 100%;
    background-image: linear-gradient(to top, #fbc2eb 0%, #a6c1ee 100%);
    background-size: cover;
    background-repeat: no-repeat;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

.calculator-container {
    width: 100%;
    max-width: 420px;
    padding: 20px;
}

.calculator-card {
    background-color: white;
    border-radius: 20px;
    overflow: hidden;
    border: 1px solid var(--violet-light);
    box-shadow: 0 10px 25px -5px rgba(124, 58, 237, 0.1), 0 8px 10px -6px rgba(124, 58, 237, 0.1);
}

.card-header {
    background-color: var(--violet-dark);
    padding: 24px;
    display: flex;
    align-items: center;
    position: relative;
}

.header-logo {
    height: 40px;
    width: 40px;
    margin-right: 8px;
}

.header-title {
    color: white;
    font-size: 24px;
    font-weight: bold;
    margin: 0;
}

.card-content {
    padding: 24px;
}

.output-display {
    background-color: var(--violet-lightest);
    border-radius: 8px;
    padding: 16px;
    margin-bottom: 24px;
    border: 1px solid var(--violet-light);
}

.expression-text {
    text-align: right;
    color: var(--violet-dark);
    font-size: 18px;
    margin-bottom: 4px;
}

.result-text {
    text-align: right;
    color: var(--violet-darkest);
    font-size: 30px;
    font-weight: bold;
}

.button-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
}

.btn {
    width: 100%;
    height: 60px;
    border-radius: 12px;
    font-size: 1.5rem;
    font-weight: 600;
    border: 2px solid;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn:active {
    transform: scale(0.96);
}

.btn-default {
    background-color: rgba(196, 181, 253, 0.2);
    color: var(--violet-darkest);
    border-color: rgba(196, 181, 253, 0.4);
}

.btn-default:hover {
    background-color: rgba(196, 181, 253, 0.3);
    border-color: rgba(196, 181, 253, 0.6);
}

.btn-light {
    background-color: rgba(196, 181, 253, 0.5);
    color: var(--violet-darkest);
    border-color: rgba(196, 181, 253, 0.7);
    box-shadow: 0px 0px 3px 0px rgba(124, 58, 237, 0.3);
}

.btn-light:hover {
    background-color: rgba(196, 181, 253, 0.6);
    border-color: rgba(196, 181, 253, 0.8);
}

.btn-medium {
    background-color: var(--violet-medium);
    color: white;
    border-color: #7c3aed;
    box-shadow: 0px 0px 3px 0px var(--violet-medium);
}

.btn-medium:hover {
    background-color: #7c3aed;
    border-color: var(--violet-dark);
}

.btn-dark {
    background-color: var(--violet-dark);
    color: white;
    border-color: #5b21b6;
    box-shadow: 0px 0px 3px 0px var(--violet-dark);
    font-weight: 700;
}

.btn-dark:hover {
    background-color: #5b21b6;
    border-color: var(--violet-darkest);
}

#b-u {
    visibility: hidden;
}

@media screen and (max-width: 500px) {
    .calculator-container {
        padding: 10px;
    }
    
    .btn {
        height: 50px;
        font-size: 1.3rem;
    }
}