:root {
    --primary-color: #3b82f6;
    --text-color: #1f2937;
    --bg-color: #f3f4f6;
    --card-bg: #ffffff;
    --input-bg: #f9fafb;
    --input-border: #d1d5db;
    --input-focus: #3b82f6;
}

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    min-height: 100vh;
}

.converter-container {
    background: var(--card-bg);
    width: 100%;
    max-width: 400px;
    padding: 2rem;
    border-radius: 16px;
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
    margin: 2rem auto;
}

h1 {
    text-align: center;
    font-size: 1.5rem;
    margin-top: 0;
    margin-bottom: 2rem;
    color: var(--text-color);
}

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

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    font-size: 0.9rem;
    color: #4b5563;
}

input {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: 1.25rem;
    font-family: 'Roboto Mono', monospace;
    color: var(--text-color);
    background-color: var(--input-bg);
    border: 2px solid var(--input-border);
    border-radius: 8px;
    box-sizing: border-box;
    transition: all 0.2s ease;
}

input:focus {
    outline: none;
    border-color: var(--input-focus);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

input::placeholder {
    color: #9ca3af;
}

footer {
    margin-top: 3rem;
    text-align: center;
    font-size: 0.75rem;
    color: #9ca3af;
    border-top: 1px solid #e5e7eb;
    padding-top: 1.5rem;
}

@media (max-width: 640px) {
    .converter-container {
        padding: 1.5rem;
        box-shadow: none;
        background-color: transparent;
    }

    input {
        font-size: 1.1rem;
    }
}