:root {
    --primary: #3b82f6;
    --primary-dark: #2563eb;
    --secondary: #6366f1;
    --secondary-dark: #4f46e5;
    --accent: #0ea5e9;
    --background: #0f172a;
    --surface: #1e293b;
    --surface-light: #334155;
    --text: #f8fafc;
    --text-light: #cbd5e1;
    --error: #ef4444;
    --success: #22c55e;
    --shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
}

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

body {
    background: var(--background);
    color: var(--text);
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1.5rem;
    line-height: 1.5;
}

.container {
    width: 100%;
    max-width: 800px;
    background: var(--surface);
    border-radius: 24px;
    box-shadow: var(--shadow);
    padding: 2.5rem;
    border: 1px solid var(--surface-light);
    backdrop-filter: blur(16px);
}

h1 {
    color: var(--primary);
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 2.5rem;
    letter-spacing: -0.025em;
    background: linear-gradient(to right, var(--primary), var(--accent));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.input-group {
    margin-bottom: 2rem;
}

.input-label {
    display: block;
    color: var(--text-light);
    font-weight: 500;
    margin-bottom: 0.75rem;
    font-size: 1rem;
}

.input-field {
    width: 100%;
    padding: 1rem 1.25rem;
    border: 2px solid var(--surface-light);
    border-radius: 12px;
    transition: all 0.3s ease;
    font-size: 1rem;
    background: var(--surface);
    color: var(--text);
}

.input-field:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.1);
}

.symbols-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(45px, 1fr));
    gap: 0.5rem;
    margin-bottom: 2rem;
    padding: 1rem;
    background: var(--surface-light);
    border-radius: 16px;
}

.symbol-btn {
    padding: 0.75rem;
    border: none;
    border-radius: 8px;
    background: var(--primary);
    color: var(--text);
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s ease;
    cursor: pointer;
}

.symbol-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
    filter: brightness(110%);
}

.operator-btn {
    background: var(--secondary);
}

.parenthesis-btn {
    background: var(--accent);
}

.evaluate-btn {
    width: 100%;
    padding: 1rem;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    color: var(--text);
    border: none;
    border-radius: 12px;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s ease;
    cursor: pointer;
    margin-top: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.evaluate-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
    filter: brightness(110%);
}

.result {
    margin-top: 2rem;
    padding: 1.25rem;
    border-radius: 12px;
    text-align: center;
    font-weight: 600;
    font-size: 1.1rem;
    transition: all 0.3s ease;
}

.result-success {
    background: rgba(34, 197, 94, 0.1);
    color: var(--success);
    border: 2px solid var(--success);
}

.result-error {
    background: rgba(239, 68, 68, 0.1);
    color: var(--error);
    border: 2px solid var(--error);
}

select {
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%23cbd5e1'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'%3E%3C/path%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    background-size: 1.2rem;
    padding-right: 2.5rem;
    cursor: pointer;
}

/* Animaciones mejoradas */
.result {
    animation: slideUp 0.4s ease-out;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Media queries mejorados */
@media (max-width: 640px) {
    .container {
        padding: 1.5rem;
        margin: 1rem;
    }

    h1 {
        font-size: 1.5rem;
        margin-bottom: 1rem;
    }

    .symbols-grid {
        grid-template-columns: repeat(auto-fit, minmax(40px, 1fr));
        gap: 0.4rem;
        padding: 0.75rem;
    }

    .symbol-btn {
        padding: 0.5rem;
        font-size: 0.9rem;
    }

    .evaluate-btn {
        padding: 1rem;
        font-size: 1rem;
    }
}

/* Efectos de focus mejorados */
button:focus, input:focus, select:focus {
    outline: none;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.3);
}

/* Scrollbar personalizado */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--surface);
}

::-webkit-scrollbar-thumb {
    background: var(--surface-light);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary);
}

/* Añadir estas nuevas clases y animaciones */
.container.success-border {
    animation: glowSuccess 1s ease-in-out;
}

.container.error-border {
    animation: glowError 1s ease-in-out;
}

@keyframes glowSuccess {
    0% {
        border-color: var(--surface-light);
        box-shadow: var(--shadow);
    }
    50% {
        border-color: var(--success);
        box-shadow: 0 0 20px rgba(34, 197, 94, 0.3);
    }
    100% {
        border-color: var(--surface-light);
        box-shadow: var(--shadow);
    }
}

@keyframes glowError {
    0% {
        border-color: var(--surface-light);
        box-shadow: var(--shadow);
    }
    50% {
        border-color: var(--error);
        box-shadow: 0 0 20px rgba(239, 68, 68, 0.3);
    }
    100% {
        border-color: var(--surface-light);
        box-shadow: var(--shadow);
    }
}