:root {
    --bg-color: #131314;
    --card-color: #1e1f20;
    --input-bg: #131314;
    --text-primary: #e3e3e3;
    --text-secondary: #c4c7c5;
    --result-color: #ffffff;
    --border-color: #444746;
    --navbar-bg: #131314;
}

body.light-mode {
    --bg-color: #f0f2f5;
    --card-color: #ffffff;
    --input-bg: #f8f9fa;
    --text-primary: #1f1f1f;
    --text-secondary: #5f6368;
    --result-color: #1a73e8;
    --border-color: #dadce0;
    --navbar-bg: #f0f2f5;
}

body {
    margin: 0;
    padding: 0;
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: 'Montserrat', sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.topo {
    width: 100%;
    padding: 15px 30px;
    background-color: var(--navbar-bg);
    position: fixed;
    top: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    box-sizing: border-box;
}

.topo h1 {
    margin: 0;
    font-size: 1.2rem;
    font-weight: 700;
}

#theme-toggle {
    position: absolute;
    right: 30px;
    padding: 8px 16px;
    border-radius: 20px;
    border: 1px solid var(--border-color);
    background: var(--card-color);
    color: var(--text-primary);
    cursor: pointer;
    font-family: 'Montserrat', sans-serif;
    font-size: 0.8rem;
    font-weight: 600;
    transition: all 0.3s ease;
}

#theme-toggle:hover {
    background: var(--border-color);
}

.container {
    margin-top: 100px;
    width: 90%;
    max-width: 450px;
    display: flex;
    flex-direction: column;
}

.card {
    background-color: var(--card-color);
    padding: 30px;
    border-radius: 24px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.campo { margin-bottom: 20px; }
label {
    display: block;
    margin-bottom: 8px;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
}

input, select {
    width: 100%;
    background-color: var(--input-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 12px;
    color: var(--text-primary);
    font-family: 'Montserrat', sans-serif;
    font-size: 1rem;
    outline: none;
    box-sizing: border-box;
}

#resultado {
    display: none;
    margin-top: 40px;
    text-align: center;
    color: var(--result-color);
    font-size: 2.2rem;
    font-weight: 700;
    animation: fadeIn 0.4s ease-out;
}

.footer {
    margin-top: auto;
    padding: 20px;
    font-size: 0.7rem;
    color: var(--text-secondary);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}