.main-header {
    padding: 2rem 0;
    width: min(1180px, calc(100% - 40px));
    margin: 0 auto;
    display: flex;
    align-items: center;
}

.brand-link {
    color: rgba(255, 255, 255, 0.48);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 700;
    letter-spacing: 0.02em;
    transition: color .25s ease, transform .25s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.brand-link:hover {
    color: #ffffff;
    transform: translateX(-2px);
}

:root {
    --bg-main: #0b0f19;
    --bg-card: #111827;
    --border-color: rgba(255, 255, 255, 0.08);
    --text-main: #f3f4f6;
    --text-muted: #9ca3af;
    --primary: #3b82f6;
    --primary-hover: #2563eb;
}

/* Contenedor Principal */
.container {
    min-height: calc(100vh - 140px);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem 1rem;
    box-sizing: border-box;
}

/* Tarjeta Central */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    width: 100%;
    max-width: 600px;
    padding: 2.5rem;
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.3);
}

.card-header {
    margin-bottom: 2rem;
    text-align: left;
}

.card-header h1 {
    font-size: 1.8rem;
    font-weight: 800;
    margin: 0 0 0.5rem 0;
    color: var(--text-main);
    letter-spacing: -0.025em;
}

.subtitle {
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.5;
    margin: 0;
}

/* Formulario e Inputs */
.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label, .result-section label {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Contenedor unificado del Input + Botón */
.hash-box-wrapper {
    display: flex;
    align-items: center;
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.hash-box-wrapper:focus-within {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

/* Estilos específicos para el botón interno */
#btnShorten {
    height: 100%;
    align-self: stretch;
}

#btnShorten:hover {
    background: rgba(255, 255, 255, 0.08) !important;
    color: #fff !important;
}

/* Sección de Resultados */
.result-section {
    margin-top: 1.5rem;
    animation: fadeIn 0.3s ease-out;
}

.btn-copy {
    background: transparent;
    border: none;
    border-left: 1px solid var(--border-color);
    color: var(--text-main);
    padding: 0 1.2rem;
    cursor: pointer;
    align-self: stretch;
    font-size: 1.1rem;
    transition: background 0.2s;
}

.btn-copy:hover {
    background: rgba(255, 255, 255, 0.05);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(5px); }
    to { opacity: 1; transform: translateY(0); }
}