/* Variáveis de Cores e Fontes */
:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --dark-bg: #111827;
    --light-bg: #f3f4f6;
    --text-dark: #1f2937;
    --text-light: #f9fafb;
    --font-main: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

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

body {
    font-family: var(--font-main);
    color: var(--text-dark);
    line-height: 1.6;
}

/* Cabeçalho e Navegação */
header {
    background-color: #ffffff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.nav-links {
    list-style: none;
    display: flex;
    align-items: center;
}

.nav-links li {
    margin-left: 1.5rem;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: color 0.3s;
}

.nav-links a:hover, .nav-links a.active {
    color: var(--primary-color);
}

.btn-login {
    background-color: var(--primary-color);
    color: white !important;
    padding: 0.5rem 1rem;
    border-radius: 5px;
}

/* Seções Gerais */
section {
    padding: 6rem 5% 4rem;
    min-height: 80vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.section-light { background-color: var(--light-bg); }
.section-dark { 
    background-color: var(--dark-bg); 
    color: var(--text-light);
}

section h2 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    color: var(--primary-color);
}

/* Hero Section (Home) */
.hero {
    background: linear-gradient(rgba(17, 24, 39, 0.8), rgba(17, 24, 39, 0.9)), url('https://source.unsplash.com/1600x900/?technology,data') center/cover;
    color: var(--text-light);
    height: 100vh;
}

.hero h1 { font-size: 3.5rem; margin-bottom: 1rem; }
.hero p { font-size: 1.2rem; margin-bottom: 2rem; }

.btn-primary {
    background-color: var(--primary-color);
    color: white;
    padding: 0.8rem 2rem;
    text-decoration: none;
    border-radius: 5px;
    border: none;
    font-size: 1rem;
    cursor: pointer;
    transition: background 0.3s;
}

.btn-primary:hover { background-color: var(--secondary-color); }

/* Cards (Publicações e Sistemas) */
.cards-container {
    display: flex;
    gap: 2rem;
    flex-wrap: wrap;
    justify-content: center;
}

.card {
    background: white;
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    width: 300px;
    color: var(--text-dark);
    text-align: left;
}

/* Formulário de Login */
.login-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    width: 100%;
    max-width: 400px;
    margin-top: 2rem;
}

.login-form input {
    padding: 1rem;
    border: 1px solid #ccc;
    border-radius: 5px;
    font-size: 1rem;
}

footer {
    background-color: #000;
    color: #fff;
    text-align: center;
    padding: 1.5rem;
}