/* CSS Variables for consistent theming */
:root {
    /* Primary colors */
    --purple: hsl(259, 100%, 65%);
    --light-red: hsl(0, 100%, 67%);

    /* Neutral colors */
    --white: hsl(0, 100%, 100%);
    --off-white: hsl(0, 0%, 94%);
    --light-grey: hsl(0, 0%, 86%);
    --smokey-grey: hsl(0, 1%, 44%);
    --off-black: hsl(0, 0%, 9%);

    /* Animation timings */
    --transition-fast: 0.2s ease;
    --transition-medium: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* Base styles */
body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--off-white);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    padding: 1rem;
}

/* Main calculator container */
.age-calculator {
    background-color: var(--white);
    border-radius: 20px 20px 100px 20px;
    padding: 3rem 2rem;
    max-width: 600px;
    width: 100%;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

/* Input fields section */
.input-fields {
    display: flex;
    width: 90%;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--light-grey);
    position: relative;
    gap: 1rem;
}

/* Individual input group styling */
.input-group {
    display: flex;
    flex-direction: column;
    flex: 1;
    position: relative;
}

/* Label styling */
label {
    text-transform: uppercase;
    letter-spacing: 3px;
    color: var(--smokey-grey);
    font-size: 0.75rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

/* Input field styling */
input {
    padding: 0.8rem;
    font-size: 1.5rem;
    font-weight: 700;
    border: 1px solid var(--light-grey);
    border-radius: 8px;
    width: 100%;
    max-width: 100px;
    transition: border-color var(--transition-medium),
        transform var(--transition-fast);
}

input:focus {
    outline: none;
    border-color: var(--purple);
}

/* Disable native validation UI */
input:invalid {
    box-shadow: none;
}

input::-webkit-validation-bubble-message {
    display: none;
}

/* Error message styling */
.error-message {
    color: var(--light-red);
    font-size: 0.7rem;
    font-style: italic;
    margin-top: 0.5rem;
    min-height: 20px;
    display: none;
    transform: translateY(-10px);
    opacity: 0;
    transition: transform var(--transition-medium),
        opacity var(--transition-medium);
    position: absolute;
    bottom: -1.5rem;
}

/* Error state styles */
.input-group.error label {
    color: var(--light-red);
}

.input-group.error input {
    animation: shake 0.5s ease-in-out;
    border-color: var(--light-red);
}

.input-group.error .error-message {
    display: block;
    transform: translateY(0);
    opacity: 1;
}

/* Shake animation for invalid inputs */
@keyframes shake {

    0%,
    100% {
        transform: translateX(0);
    }

    20%,
    60% {
        transform: translateX(-5px);
    }

    40%,
    80% {
        transform: translateX(5px);
    }
}

/* Submit button section */
.submit-section {
    position: relative;
    display: flex;
    justify-content: flex-end;
}

/* Calculate button styling */
.calculate-btn {
    background-color: var(--purple);
    border: none;
    border-radius: 50%;
    width: 70px;
    height: 70px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    position: absolute;
    top: -35px;
    transition: background-color var(--transition-medium),
        transform var(--transition-fast);
}

.calculate-btn:hover {
    background-color: var(--off-black);
    transform: scale(1.05);
}

.calculate-btn:active {
    transform: scale(0.98);
}

.calculate-btn img {
    width: 35px;
}

/* Results display styling */
.result-display {
    margin-top: 2rem;
}

.result-item {
    font-size: 4.5rem;
    font-weight: 900;
    font-style: italic;
    line-height: 1.1;
}

.result-number {
    color: var(--purple);
    margin-right: -3%;
    transition: all var(--transition-slow) cubic-bezier(0.68, -0.55, 0.27, 1.55);
    display: inline-block;
}

/* Animation for updated results */
.result-number.updated {
    transform: scale(1.1);
}

.result-label {
    color: var(--off-black);
}