/* ============================================
   RESET E ESTILOS GERAIS
   ============================================ */
* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f5f7fa;
    color: #333;
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ============================================
   CABEÇALHO
   ============================================ */
header {
    background: linear-gradient(135deg, #2c3e50 0%, #34495e 100%);
    color: white;
    padding: 40px 20px;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

header h1 {
    margin: 0;
    font-size: 2.5em;
    font-weight: 600;
}

header .subtitle {
    margin: 10px 0 0 0;
    font-size: 1.1em;
    opacity: 0.95;
    font-weight: 300;
}

/* ============================================
   NAVEGAÇÃO LATERAL
   ============================================ */
body {
    display: grid;
    grid-template-columns: 220px 1fr;
    grid-template-rows: auto 1fr auto;
    gap: 0;
    min-height: 100vh;
}

header {
    grid-column: 1 / -1;
}

nav {
    grid-column: 1;
    grid-row: 2;
    background-color: #34495e;
    padding: 0;
    box-shadow: 2px 0 8px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 80px;
    height: fit-content;
    max-height: calc(100vh - 80px);
    overflow-y: auto;
}

nav .container {
    padding: 0;
}

nav ul {
    list-style: none;
    padding: 10px 0;
    margin: 0;
    display: flex;
    flex-direction: column;
}

nav ul li {
    margin: 0;
    border-right: none;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

nav ul li:last-child {
    border-bottom: none;
}

nav ul li a {
    color: white;
    text-decoration: none;
    display: block;
    padding: 15px 20px;
    transition: all 0.3s ease;
    font-weight: 500;
}

nav ul li a:hover {
    background-color: #2c3e50;
    color: #3498db;
    padding-left: 25px;
}

nav ul li a.active {
    background-color: #3498db;
    color: white;
    border-left: 4px solid #fff;
    padding-left: 16px;
}

/* ============================================
   CONTEÚDO PRINCIPAL
   ============================================ */
main {
    grid-column: 2;
    grid-row: 2;
    min-height: 100%;
    padding: 40px 0;
}

footer {
    grid-column: 1 / -1;
    grid-row: 3;
}

section, article {
    padding: 30px;
    margin: 20px 0;
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    transition: box-shadow 0.3s ease;
}

section:hover, article:hover {
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.12);
}

section h2, article h2 {
    color: #2c3e50;
    border-bottom: 3px solid #3498db;
    padding-bottom: 10px;
    margin-top: 0;
}

section h3, article h3 {
    color: #34495e;
    margin-top: 25px;
}

section ul, article ul {
    line-height: 1.8;
}

section li, article li {
    margin-bottom: 12px;
}

/* ============================================
   LISTAS ESPECIAIS
   ============================================ */
.tips-list li {
    margin-bottom: 15px;
    padding-left: 8px;
    border-left: 4px solid #3498db;
    padding: 10px;
    background-color: #ecf0f1;
    border-radius: 4px;
}

.posture-checklist li {
    margin-bottom: 12px;
    padding: 12px;
    background-color: #f0f8ff;
    border-left: 4px solid #27ae60;
    border-radius: 4px;
}

/* ============================================
   BOTÕES
   ============================================ */
.btn, button {
    background-color: #3498db;
    color: white;
    padding: 12px 24px;
    border: none;
    border-radius: 6px;
    font-size: 1em;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 600;
    box-shadow: 0 2px 6px rgba(52, 152, 219, 0.3);
}

.btn:hover, button:hover {
    background-color: #2980b9;
    box-shadow: 0 4px 12px rgba(52, 152, 219, 0.4);
    transform: translateY(-2px);
}

.btn:active, button:active {
    transform: translateY(0);
}

.extra-tip {
    margin-top: 30px;
    padding: 20px;
    background-color: #f9f9f9;
    border-left: 5px solid #27ae60;
    border-radius: 6px;
}

#mensagem {
    margin-top: 15px;
    padding: 15px;
    background-color: #d5f4e6;
    color: #27ae60;
    border-radius: 4px;
    display: none;
    font-weight: 500;
}

#mensagem.visible {
    display: block;
    animation: fadeIn 0.3s ease;
}

/* ============================================
   GALERIA DE IMAGENS
   ============================================ */
.gallery {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin: 25px 0;
}

.gallery-item {
    background-color: #ecf0f1;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
}

.gallery-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
}

.gallery-item img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    display: block;
}

.image-placeholder {
    width: 100%;
    height: 200px;
    background: linear-gradient(135deg, #3498db 0%, #2980b9 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 0.9em;
    text-align: center;
    padding: 10px;
}

.gallery-item p {
    padding: 12px;
    margin: 0;
    font-size: 0.9em;
    color: #555;
}

/* ============================================
   SEÇÃO DE VÍDEOS
   ============================================ */
.video-section {
    margin: 25px 0;
}

.videos-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    margin: 20px 0;
}

.video-item {
    background-color: white;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    transition: box-shadow 0.3s ease;
}

.video-item:hover {
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
}

.video-placeholder {
    width: 100%;
    aspect-ratio: 16 / 9;
    background: linear-gradient(135deg, #27ae60 0%, #229954 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 3em;
    cursor: pointer;
    transition: opacity 0.3s ease;
}

.video-placeholder:hover {
    opacity: 0.9;
}

.video-item iframe {
    width: 100%;
    height: auto;
    aspect-ratio: 16 / 9;
    border: none;
}

.video-item h4 {
    padding: 15px;
    margin: 0;
    color: #2c3e50;
}

.video-item p {
    padding: 0 15px 15px 15px;
    margin: 0;
    color: #666;
    font-size: 0.9em;
}

/* ============================================
   RODAPÉ
   ============================================ */
footer {
    text-align: center;
    padding: 30px 20px;
    background: #2c3e50;
    color: white;
    margin-top: 40px;
    border-top: 4px solid #3498db;
}

footer p {
    margin: 0;
    font-size: 0.95em;
    opacity: 0.9;
}

/* ============================================
   RESPONSIVIDADE
   ============================================ */
@media (max-width: 768px) {
    body {
        grid-template-columns: 1fr;
        grid-template-rows: auto auto 1fr auto;
    }

    header h1 {
        font-size: 1.8em;
    }

    header .subtitle {
        font-size: 0.95em;
    }

    nav {
        grid-column: 1;
        grid-row: 2;
        position: static;
        max-height: none;
        padding: 0;
    }

    nav ul {
        flex-direction: row;
        flex-wrap: wrap;
        justify-content: center;
    }

    nav ul li {
        border-bottom: none;
        border-right: 1px solid rgba(255, 255, 255, 0.2);
    }

    nav ul li:last-child {
        border-right: none;
    }

    nav ul li a {
        padding: 12px 15px;
    }

    main {
        grid-column: 1;
        grid-row: 3;
    }

    section, article {
        padding: 20px;
        margin: 15px 0;
    }

    main {
        padding: 20px 0;
    }

    .gallery {
        grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
        gap: 15px;
    }

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

    .tips-list li,
    .posture-checklist li {
        padding: 12px 8px;
        padding-left: 15px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }

    header {
        padding: 25px 15px;
    }

    header h1 {
        font-size: 1.5em;
    }

    header .subtitle {
        font-size: 0.9em;
    }

    nav ul li a {
        padding: 10px;
        font-size: 0.9em;
    }

    section, article {
        padding: 15px;
    }

    .btn, button {
        padding: 10px 20px;
        font-size: 0.95em;
    }

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

    .gallery-item img,
    .image-placeholder {
        height: 150px;
    }
}