:root {
    --bg-color: #e0f2fe;
    --card-bg: #ffffff;
    --text: #0c4a6e;
    --primary: #0ea5e9;
    --primary-hover: #0284c7;
    --wave-color: #bae6fd;
}

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

body {
    font-family: 'Nunito', sans-serif;
    background-color: var(--bg-color);
    color: var(--text);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    position: relative;
    overflow-x: hidden;
}

.wave-bg {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 50vh;
    background: url('data:image/svg+xml;utf8,<svg viewBox="0 0 1440 320" xmlns="http://www.w3.org/2000/svg"><path fill="%23bae6fd" fill-opacity="1" d="M0,96L48,112C96,128,192,160,288,160C384,160,480,128,576,112C672,96,768,96,864,112C960,128,1056,160,1152,160C1248,160,1344,128,1392,112L1440,96L1440,320L1392,320C1344,320,1248,320,1152,320C1056,320,960,320,864,320C768,320,672,320,576,320C480,320,384,320,288,320C192,320,96,320,48,320L0,320Z"></path></svg>');
    background-size: cover;
    background-position: bottom;
    z-index: -1;
}

.container {
    width: 100%;
    max-width: 500px;
    z-index: 1;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

h1 {
    font-size: 2.5rem;
    font-weight: 800;
    color: #0369a1;
}

.highlight {
    color: var(--primary);
}

.subtitle {
    color: #075985;
}

.calculator-card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 1.5rem;
    box-shadow: 0 10px 25px -5px rgba(14, 165, 233, 0.15);
}

.input-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: #0c4a6e;
}

.input-wrapper {
    display: flex;
    gap: 0.5rem;
}

input[type="number"],
select {
    width: 100%;
    padding: 1rem;
    border: 2px solid #e0f2fe;
    border-radius: 0.75rem;
    font-size: 1.1rem;
    font-family: inherit;
    outline: none;
    transition: border-color 0.2s;
    color: var(--text);
    background: #f0f9ff;
}

input:focus,
select:focus {
    border-color: var(--primary);
    background: white;
}

.checkbox-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.checkbox-group input {
    width: auto;
}

.checkbox-group label {
    margin-bottom: 0;
    font-weight: 600;
}

.primary-btn {
    width: 100%;
    background: var(--primary);
    color: white;
    border: none;
    padding: 1rem;
    border-radius: 0.75rem;
    font-size: 1.2rem;
    font-weight: 800;
    cursor: pointer;
    transition: all 0.2s;
    box-shadow: 0 4px 12px rgba(14, 165, 233, 0.3);
}

.primary-btn:hover,
.primary-btn:focus {
    background: var(--primary-hover);
    transform: translateY(-2px);
    outline: none;
}

.result-card {
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    padding: 2rem;
    border-radius: 1.5rem;
    margin-top: 2rem;
    text-align: center;
    box-shadow: 0 10px 25px -5px rgba(14, 165, 233, 0.15);
    animation: slideUp 0.5s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hidden {
    display: none;
}

.result-label {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: #075985;
    margin-bottom: 0.5rem;
}

#result-liters {
    font-size: 3.5rem;
    font-weight: 800;
    color: var(--primary);
    line-height: 1;
    margin-bottom: 0.5rem;
}

.result-cups {
    font-size: 1.1rem;
    color: #0c4a6e;
    margin-bottom: 1.5rem;
}

.water-visual {
    width: 60px;
    height: 100px;
    border: 3px solid #0c4a6e;
    border-radius: 0 0 1rem 1rem;
    border-top: none;
    margin: 0 auto;
    position: relative;
    overflow: hidden;
    background: rgba(255, 255, 255, 0.5);
}

.water-level {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 0%;
    background: var(--primary);
    transition: height 1s ease-out;
}

.converter-area {
    margin-top: 1.5rem;
    padding-top: 1rem;
    border-top: 1px solid #e0f2fe;
}

.converter-area h3 {
    font-size: 1rem;
    color: #075985;
    margin-bottom: 0.5rem;
}