/* ==========================================================================
   1. VARIÁVEIS DE TEMA (CLARO / ESCURO)
   ========================================================================== */
:root {
    --bg-color: #f8f9fa;
    --text-color: #212529;
    --text-muted: #6c757d;
    --primary: #0d6efd;
    --primary-hover: #0b5ed7;
    --card-bg: #ffffff;
    --card-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    --border-color: #dee2e6;
    --step-bg: #f1f3f5;
    --step-border: #0d6efd;
    --danger-color: #dc3545;
    --success-color: #198754;
    --nav-bg: #ffffff;
    --blockquote-bg: #f1f3f5;
    --blockquote-border: #0d6efd;
    --input-bg: #ffffff;
}

[data-theme="dark"] {
    --bg-color: #0d1117;
    --card-bg: #161b22;
    --step-bg: #1c2128;
    --nav-bg: #161b22;
    --input-bg: #0d1117;
    --blockquote-bg: #1c2128;
    --text-color: #e6edf3;
    --text-muted: #8b949e;
    --primary: #58a6ff;
    --primary-hover: #79c0ff;
    --border-color: #30363d;
    --card-shadow: 0 2px 16px rgba(0, 0, 0, 0.4);
    --step-border: #58a6ff;
    --danger-color: #f85149;
    --success-color: #3fb950;
    --blockquote-border: #58a6ff;
}

/* ==========================================================================
   2. RESET E LAYOUT BASE
   ========================================================================== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s ease, color 0.3s ease;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    line-height: 1.6;
}

main {
    flex: 1;
    padding: 2.5rem 2rem;
    max-width: 900px;
    margin: 0 auto;
    width: 100%;
    animation: fadeIn 0.4s ease;
}

/* ==========================================================================
   3. TIPOGRAFIA E ELEMENTOS GERAIS
   ========================================================================== */
h1 {
    font-size: 1.9rem;
    font-weight: 700;
    margin-bottom: 1.25rem;
    color: var(--primary);
    letter-spacing: -0.5px;
}

h2 {
    font-size: 1.3rem;
    font-weight: 600;
    margin: 2rem 0 0.75rem;
    color: var(--text-color);
    padding-bottom: 0.4rem;
    border-bottom: 1px solid var(--border-color);
}

p {
    line-height: 1.75;
    margin-bottom: 1rem;
    color: var(--text-color);
}

ul {
    margin: 0 0 1.5rem 1.75rem;
}

li {
    margin-bottom: 0.5rem;
    line-height: 1.7;
}

blockquote {
    background-color: var(--blockquote-bg);
    border-left: 4px solid var(--blockquote-border);
    padding: 1rem 1.25rem;
    margin: 1.25rem 0;
    border-radius: 0 6px 6px 0;
    font-style: italic;
    color: var(--text-muted);
}

a:focus-visible, 
button:focus-visible, 
input:focus-visible {
    outline: 3px solid var(--primary);
    outline-offset: 3px;
    border-radius: 4px;
}

/* ==========================================================================
   4. NAVEGAÇÃO E RODAPÉ
   ========================================================================== */
nav {
    background-color: var(--nav-bg);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--card-shadow);
    position: sticky;
    top: 0;
    z-index: 100;
    gap: 1rem;
}

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 10px;
    letter-spacing: -0.3px;
    flex-shrink: 0;
}

.nav-links {
    display: flex;
    gap: 1.5rem;
    align-items: center;
    flex-wrap: wrap;
}

.nav-links .nav-link {
    text-decoration: none;
    color: var(--text-muted);
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.2s;
    white-space: nowrap;
}

.nav-links .nav-link.ativo {
    color: var(--primary);
    font-weight: 600;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    cursor: pointer;
    font-size: 1rem;
    color: var(--text-color);
    padding: 0.3rem 0.5rem;
    transition: border-color 0.2s, background-color 0.2s;
    flex-shrink: 0;
}

.theme-toggle:hover {
    border-color: var(--primary);
    background-color: var(--step-bg);
}

.nav-menu-btn {
    display: none;
    background: none;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    cursor: pointer;
    font-size: 1.2rem;
    color: var(--text-color);
    padding: 0.3rem 0.55rem;
    line-height: 1;
    transition: border-color 0.2s, background-color 0.2s;
}

.nav-menu-btn:hover {
    border-color: var(--primary);
    background-color: var(--step-bg);
}

.nav-dropdown {
    display: none;
    position: absolute;
    top: calc(100% + 6px);
    right: 1rem;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-shadow: var(--card-shadow);
    z-index: 200;
    min-width: 180px;
    overflow: hidden;
    animation: fadeIn 0.2s ease;
}

.nav-dropdown.aberto {
    display: block;
}

.nav-dropdown a,
.nav-dropdown button.theme-toggle-dropdown {
    display: block;
    width: 100%;
    padding: 0.75rem 1.1rem;
    text-decoration: none;
    color: var(--text-color);
    font-size: 0.93rem;
    font-weight: 500;
    background: none;
    border: none;
    border-bottom: 1px solid var(--border-color);
    text-align: left;
    cursor: pointer;
    transition: background-color 0.15s;
}

.nav-dropdown a:last-child,
.nav-dropdown button.theme-toggle-dropdown:last-child {
    border-bottom: none;
}

.nav-dropdown a:hover,
.nav-dropdown button.theme-toggle-dropdown:hover {
    background-color: var(--step-bg);
}

.nav-dropdown a.ativo {
    color: var(--primary);
    font-weight: 600;
}

footer {
    background-color: var(--nav-bg);
    text-align: center;
    padding: 1.5rem;
    border-top: 1px solid var(--border-color);
    margin-top: auto;
}

.footer-content {
    display: flex;
    flex-direction: column;
    gap: 0.3rem;
    font-size: 0.875rem;
    color: var(--text-muted);
}

.social-links {
    margin-top: 0.5rem;
}

.social-links a {
    color: var(--primary);
    text-decoration: none;
    margin: 0 0.5rem;
    transition: opacity 0.2s;
}

.social-links a:hover {
    opacity: 0.75;
}

/* ==========================================================================
   5. COMPONENTES DO SISTEMA (Caixas, Alertas e Botões)
   ========================================================================== */
.info-box {
    background-color: var(--step-bg);
    border-left: 4px solid #3fb950;
    padding: 1rem 1.25rem;
    margin-bottom: 1.25rem;
    border-radius: 0 6px 6px 0;
    font-size: 0.95em;
    line-height: 1.6;
    color: var(--text-color);
}

.equation-container {
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    box-shadow: var(--card-shadow);
}

.equation-row {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    font-size: 1.15rem;
    flex-wrap: wrap;
}

.equation-row input[type="text"] {
    padding: 0.45rem 0.6rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background-color: var(--input-bg);
    color: var(--text-color);
    font-size: 1rem;
    text-align: center;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.equation-row input[type="text"]:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.15);
}

.equation-row .eq-input  { width: 120px; }
.equation-row .num-input { width: 65px; }

.btn {
    padding: 0.6rem 1.2rem;
    border: none;
    border-radius: 6px;
    font-size: 0.95rem;
    cursor: pointer;
    font-weight: 600;
    transition: background-color 0.2s, color 0.2s, transform 0.1s;
}

.btn:active {
    transform: scale(0.98);
}

.btn-add {
    background-color: transparent;
    color: var(--primary);
    border: 2px dashed var(--primary);
    width: 100%;
    margin-bottom: 1.25rem;
    opacity: 0.85;
}

.btn-add:hover {
    background-color: var(--primary);
    color: #ffffff;
    opacity: 1;
}

.btn-generate {
    background-color: var(--primary);
    color: #ffffff;
    width: 100%;
    padding: 0.85rem;
    font-size: 1rem;
    letter-spacing: 0.5px;
}

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

.btn-remove {
    background: none;
    border: none;
    color: var(--danger-color);
    font-size: 1.1rem;
    cursor: pointer;
    margin-left: 0.25rem;
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.2s, transform 0.2s;
}

.btn-remove:hover {
    background-color: rgba(248, 81, 73, 0.12);
    transform: scale(1.15);
}

.erro-inline {
    background-color: rgba(248, 81, 73, 0.1);
    border-left: 4px solid var(--danger-color);
    color: var(--danger-color);
    padding: 0.75rem 1rem;
    border-radius: 0 6px 6px 0;
    margin-bottom: 1rem;
    font-weight: 500;
    font-size: 0.95rem;
    overflow: hidden;
    max-height: 100px;
    animation: fadeIn 0.3s ease;
}

.erro-inline.sumindo {
    animation: fadeOut 0.5s ease forwards;
    overflow: hidden;
}

/* ==========================================================================
   6. CONTAINER DE RESOLUÇÃO E PASSOS DO TCR
   ========================================================================== */
#solution-container {
    display: none;
    margin-top: 2rem;
    padding: 1.75rem;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-top: 3px solid var(--primary);
    border-radius: 10px;
    box-shadow: var(--card-shadow);
    animation: fadeIn 0.5s ease;
}

#solution-container h2 {
    border-bottom: none;
    margin-top: 0;
    margin-bottom: 1.5rem;
}

.step {
    background-color: var(--step-bg);
    padding: 1.25rem;
    margin-bottom: 1rem;
    border-radius: 8px;
    border-left: 4px solid var(--step-border);
    overflow-x: auto;
    word-break: break-word;
    overflow-wrap: break-word;
}

.step-title {
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--primary);
    font-size: 0.95rem;
    text-transform: uppercase;
    letter-spacing: 0.4px;
}

.step p,
.step span,
.step div {
    overflow-wrap: break-word;
    word-break: break-word;
}

.step .MathJax,
.step mjx-container {
    overflow-x: auto;
    max-width: 100%;
}

#barra-navegacao {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    gap: 1rem;
}

#contador-passos {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
    white-space: nowrap;
}

#barra-navegacao button {
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background-color: var(--step-bg);
    color: var(--text-color);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s, border-color 0.2s, opacity 0.2s;
}

#barra-navegacao button:hover:not(:disabled) {
    background-color: var(--primary);
    border-color: var(--primary);
    color: #ffffff;
}

#barra-navegacao button:disabled {
    opacity: 0.35;
    cursor: not-allowed;
}

/* ==========================================================================
   7. ANIMAÇÕES
   ========================================================================== */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(12px); }
    to   { opacity: 1; transform: translateY(0); }
}

@keyframes fadeOut {
    from {
        opacity: 1;
        max-height: 100px;
        margin-bottom: 1rem;
        padding-top: 0.75rem;
        padding-bottom: 0.75rem;
    }
    to {
        opacity: 0;
        max-height: 0;
        margin-bottom: 0;
        padding-top: 0;
        padding-bottom: 0;
    }
}

/* ==========================================================================
   8. RESPONSIVIDADE
   ========================================================================== */
@media (max-width: 768px) {
    nav {
        padding: 0.85rem 1.25rem;
        position: relative;
    }

    .nav-links {
        display: none;
    }

    .nav-menu-btn {
        display: block;
    }

    main {
        padding: 2rem 1.25rem;
    }

    h1 { font-size: 1.5rem; }
    h2 { font-size: 1.15rem; }

    .equation-container { padding: 1.25rem; }

    .equation-row {
        font-size: 1rem;
        gap: 0.4rem;
    }

    .equation-row .eq-input  { width: 105px; }
    .equation-row .num-input { width: 58px; }

    #solution-container { padding: 1.25rem; }

    #barra-navegacao { flex-wrap: wrap; gap: 0.6rem; }

    #barra-navegacao button {
        flex: 1;
        min-width: 80px;
        text-align: center;
        padding: 0.5rem 0.6rem;
        font-size: 0.85rem;
    }

    #contador-passos {
        width: 100%;
        text-align: center;
        order: -1;
    }
}

@media (max-width: 480px) {
    nav {
        padding: 0.75rem 1rem;
    }

    .logo {
        font-size: 0.95rem;
        gap: 7px;
    }

    .logo img {
        height: 22px;
        width: 22px;
    }

    main {
        padding: 1.5rem 0.9rem;
    }

    h1 {
        font-size: 1.2rem;
        letter-spacing: -0.3px;
    }

    h2 {
        font-size: 0.98rem;
        margin: 1.5rem 0 0.6rem;
    }

    p, li { font-size: 0.91rem; }

    blockquote {
        padding: 0.75rem 1rem;
        font-size: 0.88rem;
    }

    .equation-container {
        padding: 0.9rem;
        border-radius: 8px;
    }

    .equation-row {
        font-size: 0.88rem;
        gap: 0.3rem;
        flex-wrap: nowrap;
        align-items: center;
        margin-bottom: 0.75rem;
        overflow-x: auto;
    }

    .equation-row .eq-input {
        width: 80px;
        min-width: 60px;
        font-size: 0.88rem;
        padding: 0.4rem 0.35rem;
    }

    .equation-row .num-input {
        width: 48px;
        min-width: 40px;
        font-size: 0.88rem;
        padding: 0.4rem 0.25rem;
    }

    .btn-remove {
        font-size: 0.9rem;
        padding: 0.15rem 0.3rem;
        flex-shrink: 0;
    }

    .btn { font-size: 0.88rem; padding: 0.55rem 1rem; }

    .btn-generate {
        padding: 0.75rem;
        font-size: 0.9rem;
        letter-spacing: 0.2px;
    }

    .btn-add {
        font-size: 0.86rem;
        padding: 0.6rem 1rem;
        margin-bottom: 1rem;
    }

    #solution-container {
        padding: 1rem;
        margin-top: 1.25rem;
    }

    .step { padding: 0.85rem; }
    .step-title { font-size: 0.82rem; }

    #barra-navegacao button {
        font-size: 0.8rem;
        padding: 0.45rem 0.5rem;
    }

    footer { padding: 1.25rem 1rem; }
    .footer-content { font-size: 0.78rem; }
}