:root {
    /* --- TEMA DARK (Por defecto) --- */
    --bg-main: radial-gradient(circle at top center, #1a2a3a 0%, #0f1214 80%);
    --text-main: #e0e0e0;
    --text-title: #ffffff;
    --text-muted: #888;
    --cyan-primary: #00d2ff;
    --cyan-glow: rgba(0, 210, 255, 0.5);
    --cyan-light: #33d9ff;
    --cyan-border: rgba(0, 210, 255, 0.3);
    --cyan-shadow: rgba(0, 210, 255, 0.05);
    --cyan-shadow-strong: rgba(0, 210, 255, 0.15);
    --cyan-glow-hover: rgba(0, 210, 255, 0.6);

    /* Card & Form */
    --card-bg: rgba(20, 25, 30, 0.8);
    --card-border: rgba(0, 210, 255, 0.3);
    --input-bg: rgba(0, 0, 0, 0.3);
    --input-bg-focus: rgba(0, 0, 0, 0.5);
    --input-border: rgba(255, 255, 255, 0.15);
    --input-text: #ffffff;
    --input-placeholder: #6c757d;
    --input-disabled-bg: rgba(255, 255, 255, 0.05);
    --input-disabled-text: #888;
    --input-disabled-border: rgba(255, 255, 255, 0.05);

    /* Dynamic sections */
    --dynamic-bg: rgba(255, 255, 255, 0.03);
    --dynamic-border: rgba(255, 255, 255, 0.2);

    /* Results */
    --resultado-bg: rgba(0, 85, 164, 0.15);
    --resultado-border: #00d2ff;
    --resultado-titulo: #e0e0e0;
    --resultado-valor: #ffffff;
    --resultado-text: #e0e0e0;

    /* Alert */
    --alert-info-bg: rgba(13, 202, 240, 0.1);
    --alert-info-border: rgba(13, 202, 240, 0.3);
    --alert-info-text: #0dcaf0;

    /* Button */
    --btn-bg: #00d2ff;
    --btn-text: #000000;
    --btn-hover-bg: #33d9ff;

    /* Input group addon */
    --addon-bg: #212529;
    --addon-text: #f8f9fa;
    --addon-border: #6c757d;

    /* Shadow */
    --shadow-color: rgba(0, 210, 255, 0.05);
}

[data-theme='light'] {
    /* --- TEMA LIGHT --- */
    --bg-main: linear-gradient(135deg, #e3f2fd 0%, #f5f5f5 100%);
    --text-main: #212529;
    --text-title: #1a1d21;
    --text-muted: #6c757d;
    --cyan-primary: #00768a;
    --cyan-glow: rgba(0, 118, 138, 0.3);
    --cyan-light: #005f70;
    --cyan-border: rgba(0, 118, 138, 0.4);
    --cyan-shadow: rgba(0, 118, 138, 0.1);
    --cyan-shadow-strong: rgba(0, 118, 138, 0.2);
    --cyan-glow-hover: rgba(0, 118, 138, 0.4);

    /* Card & Form */
    --card-bg: #ffffff;
    --card-border: rgba(0, 118, 138, 0.3);
    --input-bg: #f8f9fa;
    --input-bg-focus: #ffffff;
    --input-border: #ced4da;
    --input-text: #212529;
    --input-placeholder: #6c757d;
    --input-disabled-bg: #e9ecef;
    --input-disabled-text: #6c757d;
    --input-disabled-border: #dee2e6;

    /* Dynamic sections */
    --dynamic-bg: #f8f9fa;
    --dynamic-border: rgba(0, 0, 0, 0.2);

    /* Results */
    --resultado-bg: #e3f2fd;
    --resultado-border: #00768a;
    --resultado-titulo: #212529;
    --resultado-valor: #000000;
    --resultado-text: #212529;

    /* Alert */
    --alert-info-bg: #d1ecf1;
    --alert-info-border: #bee5eb;
    --alert-info-text: #0c5460;

    /* Button */
    --btn-bg: #00768a;
    --btn-text: #ffffff;
    --btn-hover-bg: #005f70;

    /* Input group addon */
    --addon-bg: #e9ecef;
    --addon-text: #212529;
    --addon-border: #ced4da;

    /* Shadow */
    --shadow-color: rgba(0, 0, 0, 0.1);
}

/* --- ESTILOS GLOBALES DEL TEMA --- */
body {
    background: var(--bg-main) !important;
    color: var(--text-main);
    font-family: 'Roboto', sans-serif;
}

/* --- THEME TOGGLE BUTTON --- */
.theme-toggle {
    position: fixed;
    top: 80px;
    right: 20px;
    width: 45px;
    height: 45px;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    z-index: 1000;
    box-shadow: 0 4px 15px var(--shadow-color);
    transition: all 0.3s ease;
}

.theme-toggle:hover {
    transform: scale(1.1);
}

.theme-toggle i {
    font-size: 1.2rem;
    color: var(--cyan-primary);
}

/* --- CONTENEDOR PRINCIPAL --- */
.tool-container {
    max-width: 800px;
    margin: 0 auto;
}

/* --- TÍTULOS --- */
.page-title {
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-title);
    text-shadow: 0 0 10px var(--cyan-glow);
    font-weight: 700;
}

.page-desc {
    color: var(--text-main);
    font-weight: 400;
}

/* --- TARJETA DEL FORMULARIO (ESTILO HUD) --- */
.tech-card {
    background-color: var(--card-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    box-shadow: 0 0 20px var(--cyan-shadow);
}

/* --- INPUTS Y SELECTS --- */
.form-label {
    color: var(--cyan-primary);
    font-weight: 600;
    font-size: 0.9rem;
    text-transform: uppercase;
    margin-bottom: 0.5rem;
}

.form-control,
.form-select {
    background-color: var(--input-bg);
    border: 1px solid var(--input-border);
    color: var(--input-text);
    border-radius: 6px;
}

.form-control:focus,
.form-select:focus {
    background-color: var(--input-bg-focus);
    border-color: var(--cyan-primary);
    box-shadow: 0 0 0 0.25rem var(--cyan-border);
    color: var(--input-text);
}

/* Placeholders */
.form-control::placeholder {
    color: var(--input-placeholder);
    opacity: 1;
}

/* Select arrow */
.form-select {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3e%3cpath fill='none' stroke='%2300d2ff' stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='m2 5 6 6 6-6'/%3e%3c/svg%3e");
}

[data-theme='light'] .form-select {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3e%3cpath fill='none' stroke='%2300768a' stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='m2 5 6 6 6-6'/%3e%3c/svg%3e");
}

/* Input deshabilitado */
.form-control:disabled,
.form-select:disabled {
    background-color: var(--input-disabled-bg);
    color: var(--input-disabled-text);
    border-color: var(--input-disabled-border);
}

/* --- INPUT GROUP ADDON --- */
.input-group-text {
    background-color: var(--addon-bg);
    color: var(--addon-text);
    border-color: var(--addon-border);
}

/* --- SECCIONES DINÁMICAS --- */
.campos-dinamicos {
    background-color: var(--dynamic-bg);
    border: 1px dashed var(--dynamic-border);
    border-radius: 8px;
    padding: 1.5rem;
    margin-top: 1rem;
    transition: all 0.3s ease;
}

/* --- TARJETA DE RESULTADOS --- */
.resultado-card {
    background: var(--resultado-bg);
    border: 1px solid var(--resultado-border);
    border-radius: 12px;
    box-shadow: 0 0 30px var(--cyan-shadow-strong);
    position: relative;
    overflow: hidden;
}

.resultado-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background-color: var(--resultado-border);
}

.resultado-titulo {
    color: var(--resultado-titulo);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.resultado-valor {
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--resultado-valor);
    text-shadow: 0 0 15px var(--cyan-glow);
    line-height: 1.2;
    margin: 10px 0;
}

.resultado-text {
    color: var(--resultado-text);
}

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

/* --- ALERTAS --- */
.alert-info {
    background-color: var(--alert-info-bg);
    border-color: var(--alert-info-border);
    color: var(--alert-info-text);
}

/* --- BOTONES --- */
.btn-primary {
    background-color: var(--btn-bg);
    border-color: var(--btn-bg);
    color: var(--btn-text);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.btn-primary:hover {
    background-color: var(--btn-hover-bg);
    border-color: var(--btn-hover-bg);
    color: var(--btn-text);
    box-shadow: 0 0 15px var(--cyan-glow-hover);
}