/* --- Configurações Gerais --- */
:root {
    --primary-color: #007bff;
    --secondary-color: #28a745;
    --background-color: #f4f7f9;
    --container-bg: #ffffff;
    --text-color: #333;
    --border-color: #e0e0e0;
}

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

body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: flex-start;
    min-height: 100vh;
    padding: 20px;
}

/* --- Container Principal --- */
.app-container {
    width: 100%;
    max-width: 540px;
    background-color: var(--container-bg);
    border-radius: 16px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
    overflow: hidden;
}

header {
    padding: 25px;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 20px;
}

/* --- Menu de Navegação --- */
nav {
    display: flex;
    justify-content: center;
    gap: 10px;
    flex-wrap: wrap;
}

.nav-button {
    font-family: 'Poppins', sans-serif;
    padding: 10px 15px;
    border: 1px solid var(--border-color);
    background-color: transparent;
    color: #555;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.nav-button:hover {
    background-color: #f0f0f0;
    border-color: #ccc;
}

/* Estilo do botão ativo */
.nav-button.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* --- Área do Canvas --- */
main {
    padding: 20px;
}

canvas {
    display: block;
    width: 100%;
    height: auto;
    background-color: var(--container-bg);
}