:root {
    --primary-color: #ff4757;
    --bg-color: #f1f2f6;
    --card-bg: #ffffff;
}

body {
    font-family: 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    margin: 0;
    padding: 20px;
    color: #2f3542;
}

.container {
    max-width: 500px;
    margin: 0 auto;
}

h1 {
    text-align: center;
    font-size: 1.5rem;
    margin-bottom: 20px;
}

.input-group {
    background: var(--card-bg);
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

label {
    display: block;
    font-size: 0.9rem;
    font-weight: bold;
    margin-top: 15px;
}

input {
    width: 100%;
    padding: 12px;
    margin-top: 5px;
    border: 1px solid #ced4da;
    border-radius: 8px;
    box-sizing: border-box;
    font-size: 1rem;
}

.preset-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 5px;
    margin-top: 5px;
}

button {
    padding: 8px 2px;
    border: none;
    border-radius: 6px;
    background: #747d8c;
    color: white;
    cursor: pointer;
    font-size: 0.8rem;
}

button:active {
    background: #2f3542;
}

.result-area {
    margin-top: 20px;
}

.result-card {
    background: var(--card-bg);
    padding: 15px;
    border-radius: 12px;
    margin-bottom: 10px;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.result-card.secondary { border-left: 5px solid #2f3542; }
.result-card.highlight { border-left: 5px solid var(--primary-color); color: var(--primary-color); }

.label { font-size: 0.85rem; display: block; margin-bottom: 5px; color: #57606f; }
.value { font-size: 2rem; font-weight: bold; font-family: 'Courier New', Courier, monospace; }