:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --bg-color: #f3f4f6;
    --bg-gradient-start: #fdfbfb;
    --bg-gradient-end: #ebedee;
    --card-bg: #ffffff;
    --card-border: #e5e7eb;
    --card-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    --input-bg: #ffffff;
    --text-main: #111827;
    --text-muted: #6b7280;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --glow-color: rgba(79, 70, 229, 0.12);
    --nav-bg: rgba(255, 255, 255, 0.95);
    --toggle-bg: #e5e7eb;
    --toggle-thumb: #ffffff;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

body.dark {
    --primary-color: #6366f1;
    --primary-hover: #818cf8;
    --bg-color: #0f172a;
    --bg-gradient-start: #0f172a;
    --bg-gradient-end: #1e293b;
    --card-bg: #1e293b;
    --card-border: rgba(255, 255, 255, 0.05);
    --card-shadow: 0 8px 20px rgba(0, 0, 0, 0.4);
    --input-bg: rgba(15, 23, 42, 0.6);
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --success-color: #34d399;
    --glow-color: rgba(99, 102, 241, 0.12);
    --nav-bg: rgba(30, 41, 59, 0.85);
    --toggle-bg: #334155;
    --toggle-thumb: #94a3b8;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
    -webkit-tap-highlight-color: transparent;
}

html, body {
    overflow-x: hidden;
    width: 100%;
}

body {
    background: var(--bg-color);
    background-image: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    color: var(--text-main);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    transition: background-color 0.4s ease, color 0.4s ease, background-image 0.4s ease;
}

/* Header & Navigation */
.navbar {
    background: var(--nav-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    padding: 1rem 2rem;
    box-shadow: var(--shadow-md);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    z-index: 10;
    transition: background-color 0.4s ease, border-color 0.4s ease;
    border-bottom: 1px solid var(--border-color);
}

.navbar-top {
    display: flex;
    width: 100%;
    justify-content: space-between;
    align-items: center;
}

.navbar-controls {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.mobile-menu-btn {
    display: none;
    background: transparent;
    border: none;
    color: var(--text-main);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 0.5rem;
    transition: background-color 0.2s;
    min-height: 44px;
    align-items: center;
    justify-content: center;
}
.mobile-menu-btn:hover {
    background: rgba(128,128,128,0.1);
}

.currency-select {
    background: var(--input-bg);
    color: var(--text-main);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    padding: 0.4rem 0.5rem;
    font-size: 0.9rem;
    min-height: 44px;
    font-weight: 500;
    outline: none;
    cursor: pointer;
    transition: border-color 0.3s, box-shadow 0.3s, background-color 0.4s ease, color 0.4s ease;
}

.currency-select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--glow-color);
}

@media (min-width: 768px) {
    .navbar {
        flex-direction: row;
        justify-content: space-between;
    }
    .navbar-top {
        width: auto;
        gap: 2rem;
    }
}

.theme-toggle {
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0;
    min-height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    outline: none;
}

.toggle-track {
    width: 64px;
    height: 32px;
    background: var(--toggle-bg);
    border-radius: 16px;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 6px;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.1);
    transition: background 0.3s ease;
}

.toggle-thumb {
    position: absolute;
    top: 2px;
    left: 2px;
    width: 28px;
    height: 28px;
    background: var(--toggle-thumb);
    border-radius: 50%;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
    transition: transform 0.3s cubic-bezier(0.22, 1, 0.36, 1), background 0.3s ease;
    z-index: 2;
    transform: translateX(0); /* Estado base claro */
}

/* Dark Mode */
body.dark .toggle-thumb {
    transform: translateX(32px);
}

.toggle-track .icon-sun,
.toggle-track .icon-moon {
    font-size: 14px;
    z-index: 1;
    transition: opacity 0.3s ease, filter 0.3s ease;
    user-select: none;
    line-height: 1;
    display: block;
}

body:not(.dark) .icon-sun { opacity: 1; }
body:not(.dark) .icon-moon { opacity: 0.4; filter: grayscale(1); }
body.dark .icon-sun { opacity: 0.4; filter: grayscale(1); }
body.dark .icon-moon { opacity: 1; filter: drop-shadow(0 0 4px rgba(255,215,0,0.5)); }

/* Hover Pré-Visualização (Desktop) */
@media (hover: hover) {
    body:not(.dark) .theme-toggle:hover .toggle-thumb { transform: translateX(32px); }
    body:not(.dark) .theme-toggle:hover .icon-moon { opacity: 1; filter: drop-shadow(0 0 4px rgba(186, 169, 169, 0.5)); }
    body:not(.dark) .theme-toggle:hover .icon-sun { opacity: 0.4; }
    
    body.dark .theme-toggle:hover .toggle-thumb { transform: translateX(0); }
    body.dark .theme-toggle:hover .icon-sun { opacity: 1; filter: none; }
    body.dark .theme-toggle:hover .icon-moon { opacity: 0.4; filter: grayscale(1); }
}

/* Efeito tátil (Mobile) */
.theme-toggle:active .toggle-thumb {
    transform: scale(0.9);
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    justify-content: center;
}

.nav-btn {
    background: none;
    border: none;
    padding: 0.5rem 1rem;
    min-height: 44px;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-muted);
    cursor: pointer;
    border-radius: 0.5rem; /* match form controls */
    transition: all 0.3s ease;
}

.nav-btn:hover {
    background: var(--bg-color);
    color: var(--text-main);
}

.nav-btn.active {
    background: var(--primary-color);
    color: rgb(255, 255, 255);
    transform: scale(1.05);
    box-shadow: 0 4px 10px var(--glow-color);
}

.nav-btn.dragging {
    opacity: 0.4;
    transform: scale(0.95);
    background: var(--border-color);
    box-shadow: none;
}

@media (max-width: 767px) {
    .navbar {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        padding: 0.75rem 1rem 0;
        gap: 0.75rem;
        z-index: 1000;
    }

    .navbar-top {
        position: relative; /* Para encapsular o dropdown absoluto se aplicável */
    }

    .mobile-menu-btn {
        display: flex;
    }

    /* Menu Dropdown Style para os Controls originais da topbar */
    .navbar-controls {
        position: absolute;
        top: calc(100% + 0.75rem);
        right: 0;
        background: var(--card-bg);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        border: 1px solid var(--border-color);
        box-shadow: var(--shadow-lg);
        flex-direction: column;
        padding: 1rem;
        border-radius: 0.75rem;
        gap: 0.75rem;
        min-width: 200px;
        align-items: stretch;
        
        display: none;
        opacity: 0;
        transform: translateY(-10px);
        transition: opacity 0.3s ease, transform 0.3s ease;
    }

    .navbar-controls.show {
        display: flex;
        opacity: 1;
        transform: translateY(0);
    }

    .currency-select, .theme-toggle {
        width: 100%;
        margin: 0;
    }
    
    .theme-toggle {
        justify-content: space-between;
        padding: 0.75rem;
        border: 1px solid var(--border-color);
        border-radius: 0.5rem;
    }
    .theme-toggle::after {
        content: 'Alternar Tema';
        font-size: 0.9rem;
        font-weight: 500;
        flex-grow: 1;
        text-align: right;
    }
    
    .nav-links {
        width: calc(100% + 2rem);
        margin-left: -1rem;
        margin-right: -1rem;
        padding: 0 1rem;
        flex-wrap: nowrap;
        justify-content: flex-start;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        scrollbar-width: none;
    }
    
    .nav-links::-webkit-scrollbar {
        display: none;
    }
    
    .nav-btn {
        flex-shrink: 0;
        white-space: nowrap;
        border-radius: 0;
        border-bottom: 2px solid transparent;
        padding-bottom: 0.75rem;
    }

    .nav-btn.active {
        background: transparent;
        color: var(--primary-color);
        transform: none;
        box-shadow: none;
        border-bottom-color: var(--primary-color);
    }

    .viewport {
        margin-top: 125px; /* Compensa navbar fixa no mobile */
    }
}

/* Viewport & Slider */
.viewport {
    flex: 1;
    overflow: hidden;
    width: 100%;
    position: relative;
    display: flex;
}

.slider {
    display: flex;
    transition: transform 0.5s cubic-bezier(0.2, 0.8, 0.2, 1);
    width: 100%;
}

.slide {
    width: 100%;
    min-width: 100%;
    flex-shrink: 0;
    padding: 2rem 1rem;
    display: flex;
    justify-content: center;
    align-items: center;
    box-sizing: border-box;
}

/* Calculator Card */
.calculator-card {
    background: var(--card-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--card-border);
    border-radius: 1rem;
    box-shadow: var(--card-shadow);
    width: 100%;
    max-width: 500px;
    padding: 2rem;
    margin: auto;
    transition: background-color 0.4s ease, border-color 0.4s ease, box-shadow 0.4s ease;
}

.calc-header {
    margin-bottom: 2rem;
    text-align: center;
}

.calc-header h2 {
    font-size: 1.5rem;
    color: var(--text-main);
    margin-bottom: 0.5rem;
}

.calc-header p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* Form Groups */
.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-main);
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.input-prefix {
    position: absolute;
    left: 1rem;
    color: var(--text-muted);
    font-weight: 500;
}

.input-suffix {
    position: absolute;
    right: 1rem;
    color: var(--text-muted);
    font-weight: 500;
}

.form-control {
    width: 100%;
    padding: 0.75rem 1rem;
    min-height: 44px;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    outline: none;
    background: var(--input-bg);
    color: var(--text-main);
    transition: border-color 0.3s, box-shadow 0.3s, transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), background-color 0.4s ease, color 0.4s ease;
}

.form-control:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--glow-color);
    transform: translateY(-2px);
}

.has-prefix {
    padding-left: 2.75rem;
}

.has-suffix {
    padding-right: 2.75rem;
}

/* Button */
.btn-calc {
    width: 100%;
    background: var(--primary-color);
    color: white;
    border: none;
    min-height: 44px;
    padding: 0.875rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: background 0.3s, transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), box-shadow 0.3s;
    margin-top: 0.5rem;
}

.btn-calc:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px var(--glow-color);
}

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

/* Results Area */
.result-area {
    margin-top: 2rem;
    padding: 1.5rem;
    background: var(--bg-color);
    border-radius: 0.5rem;
    border-left: 4px solid var(--success-color);
    display: none;
}

.result-area.show {
    display: block;
    animation: fadeIn 0.3s ease-out;
}

.result-label {
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.result-value {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--success-color);
    word-break: break-word;
    overflow-wrap: anywhere;
}

.result-detail {
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-top: 0.5rem;
    padding-top: 0.5rem;
    border-top: 1px dashed var(--border-color);
}

.result-explanation {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 1rem;
    text-align: center;
    font-style: italic;
    opacity: 0.8;
}

.footer {
    text-align: center;
    padding: 1.5rem;
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Erros de Validação e Destaque */
.input-error-border {
    border-color: #ef4444 !important;
    box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.2) !important;
}

.input-error-msg {
    color: #ef4444;
    font-size: 0.8rem;
    margin-top: 0.25rem;
    animation: fadeIn 0.3s ease-out;
}

@keyframes highlightPulse {
    0% { transform: scale(1); filter: brightness(1); }
    50% { transform: scale(1.05); filter: brightness(1.2); }
    100% { transform: scale(1); filter: brightness(1); }
}

.highlight-pulse {
    animation: highlightPulse 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}