:root {
    --bg-gradient: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
    --card-bg: rgba(255, 255, 255, 0.1);
    --text-color: #ffffff;
    --input-bg: rgba(255, 255, 255, 0.2);
    --btn-bg: #ff6b6b;
    --btn-hover: #ff5252;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
}

body {
    background: var(--bg-gradient);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--text-color);
}

.calculator-container {
    background: var(--card-bg);
    backdrop-filter: blur(15px);
    -webkit-backdrop-filter: blur(15px);
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.3);
    border: 1px solid rgba(255, 255, 255, 0.1);
    width: 90%;
    max-width: 420px;
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.calculator-container:hover {
    transform: translateY(-5px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.4);
}

h1 {
    font-weight: 600;
    margin-bottom: 30px;
    font-size: 2rem;
    letter-spacing: 1px;
}

.input-group {
    margin-bottom: 25px;
    text-align: left;
}

label {
    display: block;
    margin-bottom: 8px;
    font-size: 0.95rem;
    font-weight: 300;
}

input[type="date"] {
    width: 100%;
    padding: 14px 15px;
    border-radius: 12px;
    border: none;
    outline: none;
    background: var(--input-bg);
    color: var(--text-color);
    font-size: 1rem;
    transition: background 0.3s ease, box-shadow 0.3s ease;
}

/* Fix for date picker icon on dark backgrounds */
input[type="date"]::-webkit-calendar-picker-indicator {
    filter: invert(1);
    cursor: pointer;
    opacity: 0.8;
}

input[type="date"]::-webkit-calendar-picker-indicator:hover {
    opacity: 1;
}

input[type="date"]:focus {
    background: rgba(255, 255, 255, 0.3);
    box-shadow: 0 0 0 2px rgba(255, 255, 255, 0.5);
}

button {
    width: 100%;
    padding: 15px;
    border-radius: 12px;
    border: none;
    background: var(--btn-bg);
    color: white;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.3s ease, transform 0.1s ease, box-shadow 0.3s ease;
    box-shadow: 0 4px 15px rgba(255, 107, 107, 0.4);
}

button:hover {
    background: var(--btn-hover);
    box-shadow: 0 6px 20px rgba(255, 107, 107, 0.6);
}

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

.result-container {
    margin-top: 30px;
    padding: 20px;
    background: rgba(0, 0, 0, 0.25);
    border-radius: 12px;
    min-height: 80px;
    display: flex;
    justify-content: center;
    align-items: center;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

#age-result {
    font-size: 1.15rem;
    line-height: 1.6;
    font-weight: 300;
}

.highlight {
    font-weight: 600;
    color: #4facfe;
    font-size: 1.3rem;
    display: inline-block;
    padding: 0 4px;
}

.checkbox-group {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    margin-bottom: 20px;
    gap: 10px;
    text-align: left;
}

.checkbox-group label {
    margin-bottom: 0;
    cursor: pointer;
}

.checkbox-group input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
    accent-color: var(--btn-bg);
}