/* Variables globales */
:root {
    --bg-dark: #1E1E2E;
    --text-light: #F8F8F2;
    --accent-aqua: #80FFEA;
    --accent-tomato: #FF9580;
    --accent-orange: #FFCA80;
    --shadow-color: rgba(0, 0, 0, 0.2);
    --glass-bg: rgba(30, 30, 46, 0.7);
}

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

body {
    font-family: 'Roboto', sans-serif;
    background: linear-gradient(135deg, var(--bg-dark), #2D2D44);
    color: var(--text-light);
    line-height: 1.6;
    padding: 2rem;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    backdrop-filter: blur(10px);
    background: var(--glass-bg);
    border-radius: 16px;
    padding: 2rem;
    box-shadow: 0 8px 32px var(--shadow-color);
}

/* Encabezados */
h1 {
    color: var(--accent-orange);
    font-size: 3.5rem;
    text-align: center;
    margin-bottom: 2rem;
    text-shadow: 2px 2px 4px var(--shadow-color);
    background: linear-gradient(to right, var(--accent-orange), var(--accent-tomato));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

h2 {
    color: var(--accent-aqua);
    font-size: 2rem;
    margin-bottom: 1rem;
    text-shadow: 1px 1px 2px var(--shadow-color);
}

h3 {
    color: var(--accent-orange);
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

/* Secciones */
.explanation {
    margin-bottom: 3rem;
    background: rgba(26, 26, 36, 0.6);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 16px var(--shadow-color);
}

.code-example {
    display: block;
    background: rgba(26, 26, 36, 0.8);
    padding: 1.5rem;
    border-radius: 8px;
    margin: 1rem 0;
    white-space: pre;
    overflow-x: auto;
    font-family: monospace;
    color: var(--accent-aqua);
    border: 1px solid rgba(128, 255, 234, 0.2);
    box-shadow: 0 2px 8px var(--shadow-color);
}

/* Sección interactiva */
.interactive {
    display: grid;
    gap: 2rem;
}

.input-section {
    display: flex;
    flex-wrap: wrap;
    gap: 1.5rem;
    align-items: center;
    justify-content: center;
    margin-bottom: 2rem;
    background: rgba(26, 26, 36, 0.6);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: 0 4px 16px var(--shadow-color);
}

.speed-control {
    display: flex;
    align-items: center;
    gap: 1rem;
    background: rgba(26, 26, 36, 0.8);
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 8px var(--shadow-color);
}

.speed-control input[type="range"] {
    width: 150px;
    accent-color: var(--accent-aqua);
}

.speed-control .speed-value {
    min-width: 60px;
    color: var(--accent-aqua);
    font-weight: 500;
}

input[type="number"] {
    background: rgba(26, 26, 36, 0.8);
    border: 2px solid var(--accent-aqua);
    color: var(--text-light);
    padding: 0.75rem;
    border-radius: 8px;
    width: 120px;
    font-size: 1.1rem;
    transition: all 0.3s ease;
    box-shadow: 0 2px 8px var(--shadow-color);
}

input[type="number"]:focus {
    outline: none;
    box-shadow: 0 0 0 3px rgba(128, 255, 234, 0.3);
    transform: translateY(-2px);
}

button {
    background: linear-gradient(135deg, var(--accent-aqua), #60D9C7);
    color: var(--bg-dark);
    border: none;
    padding: 0.75rem 2rem;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1.1rem;
    font-weight: 500;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(128, 255, 234, 0.3);
}

button:hover {
    background: linear-gradient(135deg, var(--accent-tomato), #FF7B66);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(255, 149, 128, 0.4);
}

button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

/* Visualización */
.visualization {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.stack-container, .result-container {
    background: rgba(26, 26, 36, 0.8);
    padding: 2rem;
    border-radius: 12px;
    min-height: 300px;
    box-shadow: 0 8px 24px var(--shadow-color);
    border: 1px solid rgba(128, 255, 234, 0.1);
    backdrop-filter: blur(5px);
}

.stack {
    display: flex;
    flex-direction: column-reverse;
    gap: 1rem;
    min-height: 200px;
}

.stack-item {
    background: rgba(30, 30, 46, 0.9);
    padding: 1.2rem;
    border-radius: 8px;
    border-left: 4px solid var(--accent-aqua);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    opacity: 0;
    transform: translateX(-20px) scale(0.95);
    box-shadow: 0 4px 12px var(--shadow-color);
    display: flex;
    align-items: center;
    gap: 1rem;
}

.factorial-expression {
    color: var(--accent-aqua);
    font-weight: 500;
}

.factorial-equals {
    color: var(--text-light);
    opacity: 0.7;
}

.factorial-result {
    color: var(--accent-tomato);
    font-weight: 700;
}

.stack-item.active {
    opacity: 1;
    transform: translateX(0) scale(1);
}

.stack-item.resolving {
    border-left-color: var(--accent-tomato);
    background: rgba(255, 149, 128, 0.1);
}

.result {
    font-size: 1.4rem;
    padding: 1.5rem;
    opacity: 0;
    transition: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    text-align: center;
    background: rgba(26, 26, 36, 0.6);
    border-radius: 8px;
    transform: translateY(10px);
}

.result.show {
    opacity: 1;
    transform: translateY(0);
}

/* Responsive */
@media (max-width: 768px) {
    body {
        padding: 1rem;
    }

    .container {
        padding: 1.5rem;
    }

    h1 {
        font-size: 2.5rem;
    }

    h2 {
        font-size: 1.5rem;
    }

    .code-example {
        font-size: 0.9rem;
        padding: 1rem;
    }

    .visualization {
        grid-template-columns: 1fr;
    }

    .stack-container, .result-container {
        padding: 1.5rem;
    }
}