/* =====================
   CSS Variables & Design System
   ===================== */
:root {
    /* Color Palette */
    --color-primary: #00ADB5;
    --color-secondary: #393E46;
    --color-dark: #222831;
    --color-light: #EEEEEE;
    --color-accent: #FFD369;
    --color-light: #F5F5F5;
    --line-height-normal: 1.6;

    --color-text-base: #EDEDED;
    --color-text-dark: #1A1A1A;
    --color-text-muted: #B0B0B0;
    
    /* Extended Color System */
    --color-primary-light: #33BDC4;
    --color-primary-dark: #008B92;
    --color-secondary-light: #5A6069;
    --color-secondary-dark: #2A2E35;
    --color-success: #10B981;
    --color-warning: #F59E0B;
    --color-error: #EF4444;
    --color-info: #3B82F6;
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    --gradient-secondary: linear-gradient(135deg, var(--color-accent), var(--color-primary));
    --gradient-dark: linear-gradient(135deg, var(--color-dark), var(--color-secondary));
    --gradient-light: linear-gradient(135deg, #ffffff, var(--color-light));
    --gradient-success: linear-gradient(135deg, var(--color-success), #059669);
    --gradient-error: linear-gradient(135deg, var(--color-error), #DC2626);
    
    /* Shadows */
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07), 0 2px 4px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1), 0 4px 6px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.1), 0 10px 10px rgba(0, 0, 0, 0.04);
    --shadow-2xl: 0 25px 50px rgba(0, 0, 0, 0.25);
    --shadow-inner: inset 0 2px 4px rgba(0, 0, 0, 0.06);
    
    /* Border Radius */
    --border-radius-xs: 4px;
    --border-radius-sm: 6px;
    --border-radius-md: 8px;
    --border-radius-lg: 12px;
    --border-radius-xl: 16px;
    --border-radius-2xl: 20px;
    --border-radius-3xl: 24px;
    --border-radius-full: 9999px;
    
    /* Typography */
    --font-family-base: 'Segoe UI', -apple-system, BlinkMacSystemFont, 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    --font-family-mono: 'SF Mono', 'Monaco', 'Inconsolata', 'Roboto Mono', 'Courier New', monospace;
    
    --font-size-xs: 0.75rem;    /* 12px */
    --font-size-sm: 0.875rem;   /* 14px */
    --font-size-base: 1rem;     /* 16px */
    --font-size-lg: 1.125rem;   /* 18px */
    --font-size-xl: 1.25rem;    /* 20px */
    --font-size-2xl: 1.5rem;    /* 24px */
    --font-size-3xl: 1.875rem;  /* 30px */
    --font-size-4xl: 2.25rem;   /* 36px */
    --font-size-5xl: 3rem;      /* 48px */
    
    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    --font-weight-extrabold: 800;
    
    --line-height-tight: 1.25;
    --line-height-snug: 1.375;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.625;
    --line-height-loose: 2;
    
    /* Spacing Scale */
    --spacing-0: 0;
    --spacing-px: 1px;
    --spacing-0-5: 0.125rem;    /* 2px */
    --spacing-1: 0.25rem;       /* 4px */
    --spacing-1-5: 0.375rem;    /* 6px */
    --spacing-2: 0.5rem;        /* 8px */
    --spacing-2-5: 0.625rem;    /* 10px */
    --spacing-3: 0.75rem;       /* 12px */
    --spacing-3-5: 0.875rem;    /* 14px */
    --spacing-4: 1rem;          /* 16px */
    --spacing-5: 1.25rem;       /* 20px */
    --spacing-6: 1.5rem;        /* 24px */
    --spacing-7: 1.75rem;       /* 28px */
    --spacing-8: 2rem;          /* 32px */
    --spacing-9: 2.25rem;       /* 36px */
    --spacing-10: 2.5rem;       /* 40px */
    --spacing-11: 2.75rem;      /* 44px */
    --spacing-12: 3rem;         /* 48px */
    --spacing-14: 3.5rem;       /* 56px */
    --spacing-16: 4rem;         /* 64px */
    --spacing-20: 5rem;         /* 80px */
    --spacing-24: 6rem;         /* 96px */
    --spacing-28: 7rem;         /* 112px */
    --spacing-32: 8rem;         /* 128px */
    
    /* Transitions */
    --transition-fast: all 0.15s ease;
    --transition-base: all 0.2s ease;
    --transition-slow: all 0.3s ease;
    --transition-slower: all 0.5s ease;
    
    /* Z-index Scale */
    --z-index-dropdown: 1000;
    --z-index-sticky: 1020;
    --z-index-fixed: 1030;
    --z-index-modal-backdrop: 1040;
    --z-index-modal: 1050;
    --z-index-popover: 1060;
    --z-index-tooltip: 1070;
    --z-index-toast: 1080;
    
    /* Breakpoints */
    --breakpoint-sm: 640px;
    --breakpoint-md: 768px;
    --breakpoint-lg: 1024px;
    --breakpoint-xl: 1280px;
    --breakpoint-2xl: 1536px;
    
    /* Interactive States */
    --focus-ring: 0 0 0 3px rgba(0, 173, 181, 0.1);
    --focus-ring-offset: 0 0 0 2px var(--color-light);
    
    /* Animation Durations */
    --duration-75: 75ms;
    --duration-100: 100ms;
    --duration-150: 150ms;
    --duration-200: 200ms;
    --duration-300: 300ms;
    --duration-500: 500ms;
    --duration-700: 700ms;
    --duration-1000: 1000ms;
}

/* =====================
   Dark Theme Variables
   ===================== */
[data-theme="dark"] {
    --color-light: #1A202C;
    --color-dark: #F7FAFC;
    --color-secondary: #4A5568;
    --color-secondary-light: #718096;
    --color-secondary-dark: #2D3748;
    
    --gradient-primary: linear-gradient(135deg, var(--color-primary), #2D3748);
    --gradient-dark: linear-gradient(135deg, #0F1419, var(--color-secondary));
    --gradient-light: linear-gradient(135deg, #2D3748, #4A5568);
    
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.2);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3), 0 1px 2px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3), 0 2px 4px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.4), 0 4px 6px rgba(0, 0, 0, 0.2);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.4), 0 10px 10px rgba(0, 0, 0, 0.2);
    
    --focus-ring-offset: 0 0 0 2px var(--color-light);
}

/* =====================
   Reset and Base Styles
   ===================== */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    height: 100%;
    -webkit-text-size-adjust: 100%;
    -ms-text-size-adjust: 100%;
    overflow-x: hidden;
   
   
}

body {
    font-family: var(--font-family-base);
    background: var(--gradient-dark);
    color: var(--color-dark);
    line-height: var(--line-height-normal);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: var(--transition-base);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

.header__logo {
    width: 50px;
    height: 50px;
    border-radius: 12px;
    background-color: var(--color-light); /* leve destaque de fundo */
    padding: 6px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    backdrop-filter: blur(2px); /* se o fundo for transparente */
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.header__logo:hover {
    transform: scale(1.05);
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.35);
    cursor: pointer;
}

/* =====================
   Accessibility: Skip Link
   ===================== */
.skip-link {
    position: absolute;
    top: -40px;
    left: var(--spacing-4);
    background: var(--color-primary);
    color: white;
    padding: var(--spacing-2) var(--spacing-4);
    border-radius: var(--border-radius-md);
    text-decoration: none;
    font-weight: var(--font-weight-medium);
    z-index: var(--z-index-tooltip);
    transition: var(--transition-fast);
}

.skip-link:focus {
    top: var(--spacing-4);
}

/* =====================
   Loading Screen
   ===================== */
.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--gradient-primary);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: var(--z-index-modal);
    color: white;
    transition: opacity var(--duration-300) ease;
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-top: 3px solid white;
    border-radius: 50%;
    animation: spin var(--duration-1000) linear infinite;
    margin-bottom: var(--spacing-4);
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* =====================
   Layout: Container
   ===================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-4);
    width: 100%;
}

/* =====================
   Header
   ===================== */
.header {
    background: var(--gradient-primary);
    color: white;
    padding: var(--spacing-8) 0;
    position: relative;
    overflow: hidden;
}

.header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Ccircle cx='30' cy='30' r='4'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    animation: float var(--duration-1000) ease-in-out infinite alternate;
}

@keyframes float {
    0% { transform: translateY(0px); }
    100% { transform: translateY(-10px); }
}

.header__content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
    z-index: 1;
    gap: var(--spacing-4);
}

.header__text {
    flex: 1;
}

.header__title {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-1);
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
    line-height: var(--line-height-tight);
}

.header__subtitle {
    font-size: var(--font-size-lg);
    opacity: 0.9;
    font-weight: var(--font-weight-light);
    line-height: var(--line-height-snug);
}

/* =====================
   Theme Toggle
   ===================== */
.theme-toggle {
    background: rgba(255, 255, 255, 0.15);
    border: 2px solid rgba(255, 255, 255, 0.25);
    border-radius: var(--border-radius-full);
    width: 52px;
    height: 52px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition-base);
    backdrop-filter: blur(10px);
    flex-shrink: 0;
}

.theme-toggle:hover {
    background: rgba(255, 255, 255, 0.25);
    transform: scale(1.05);
    border-color: rgba(255, 255, 255, 0.4);
}

.theme-toggle:focus {
    outline: none;
    box-shadow: var(--focus-ring), var(--focus-ring-offset);
}

.theme-toggle__icon {
    font-size: var(--font-size-xl);
    transition: var(--transition-base);
}

/* =====================
   Main Content
   ===================== */
.main {
    flex: 1;
    padding: var(--spacing-12) 0;
    position: relative;
}

/* =====================
   Tabs Navigation
   ===================== */
.tabs {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    background: white;
    border-radius: var(--border-radius-2xl);
    padding: var(--spacing-1);
    margin-bottom: var(--spacing-12);
    box-shadow: var(--shadow-lg);
    gap: var(--spacing-1);
    position: relative;
    overflow: hidden;
}

.tabs::before {
    content: '';
    position: absolute;
    top: var(--spacing-1);
    left: var(--spacing-1);
    width: calc(33.333% - var(--spacing-1));
    height: calc(100% - var(--spacing-2));
    background: var(--gradient-primary);
    border-radius: var(--border-radius-lg);
    transition: transform var(--duration-300) cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 0;
}

.tabs[data-active="volume"]::before {
    transform: translateX(100%);
}

.tabs[data-active="temperature"]::before {
    transform: translateX(200%);
}

.tabs__button {
    position: relative;
    z-index: 1;
    padding: var(--spacing-4) var(--spacing-3);
    border: none;
    background: transparent;
    border-radius: var(--border-radius-lg);
    cursor: pointer;
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-semibold);
    transition: var(--transition-base);
    color: var(--color-secondary);
    white-space: nowrap;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-2);
    min-height: 48px;
}

.tabs__button:hover:not(.tabs__button--active) {
    background: rgba(0, 173, 181, 0.05);
    color: var(--color-primary);
}

.tabs__button:focus {
    outline: none;
    box-shadow: inset var(--focus-ring);
}

.tabs__button--active {
    color: white;
    background: transparent;
}

.tabs__icon {
    font-size: var(--font-size-lg);
    flex-shrink: 0;
}

.tabs__text {
    font-weight: var(--font-weight-semibold);
}

/* =====================
   Converter Sections
   ===================== */
.converter {
    background: white;
    border-radius: var(--border-radius-2xl);
    padding: var(--spacing-12);
    margin-bottom: var(--spacing-12);
    box-shadow: var(--shadow-lg);
    transition: var(--transition-base);
    position: relative;
    overflow: hidden;
}

.converter::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-primary);
}

.converter--hidden {
    display: none;
}

.converter__header {
    text-align: center;
    margin-bottom: var(--spacing-12);
}

.converter__header h2 {
    font-size: var(--font-size-3xl);
    color: var(--color-secondary);
    margin-bottom: var(--spacing-2);
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
}

.converter__header p {
    color: #64748B;
    font-size: var(--font-size-lg);
    line-height: var(--line-height-relaxed);
}

/* =====================
   Form Styles
   ===================== */
.converter__form {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: var(--spacing-8);
    align-items: start;
    margin-bottom: var(--spacing-12);
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-3);
}

.input-group__label {
    font-weight: var(--font-weight-semibold);
    color: var(--color-secondary);
    font-size: var(--font-size-base);
    margin-bottom: var(--spacing-1);
}

.input-wrapper {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-3);
}

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

.input-field__input {
    width: 100%;
    padding: var(--spacing-4) var(--spacing-4);
    border: 2px solid #E2E8F0;
    border-radius: var(--border-radius-lg);
    font-size: var(--font-size-base);
    transition: var(--transition-base);
    background: white;
    font-family: var(--font-family-base);
    line-height: var(--line-height-normal);
    min-height: 48px;
}

.input-field__input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: var(--focus-ring);
}

.input-field__input:invalid {
    border-color: var(--color-error);
}

.input-field__input--readonly {
    background: #F8FAFC;
    color: var(--color-secondary);
    font-weight: var(--font-weight-semibold);
    cursor: default;
}

.input-field__loading {
    position: absolute;
    right: var(--spacing-4);
    width: 16px;
    height: 16px;
    border: 2px solid #E2E8F0;
    border-top: 2px solid var(--color-primary);
    border-radius: 50%;
    animation: spin var(--duration-1000) linear infinite;
    opacity: 0;
    transition: opacity var(--duration-200);
}

.input-field__loading--visible {
    opacity: 1;
}

.select-field {
    width: 100%;
    padding: var(--spacing-4);
    border: 2px solid #E2E8F0;
    border-radius: var(--border-radius-lg);
    font-size: var(--font-size-base);
    background: white;
    cursor: pointer;
    transition: var(--transition-base);
    font-family: var(--font-family-base);
    line-height: var(--line-height-normal);
    min-height: 48px;
    appearance: none;
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 20 20'%3e%3cpath stroke='%236b7280' stroke-linecap='round' stroke-linejoin='round' stroke-width='1.5' d='m6 8 4 4 4-4'/%3e%3c/svg%3e");
    background-position: right var(--spacing-3) center;
    background-repeat: no-repeat;
    background-size: 16px 12px;
    padding-right: var(--spacing-10);
}

.select-field:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: var(--focus-ring);
}

.input-error {
    color: var(--color-error);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-1);
    min-height: 20px;
    display: flex;
    align-items: center;
    gap: var(--spacing-1);
    opacity: 0;
    transform: translateY(-4px);
    transition: var(--transition-base);
    /* Reforço de contraste para modo escuro */
    background: transparent;
}
[data-theme="dark"] .input-error {
    color: #FF6B6B;
    background: rgba(255, 107, 107, 0.08);
}


.input-error--visible {
    opacity: 1;
    transform: translateY(0);
}
.input-error::before {
    content: '⚠️';
    font-size: var(--font-size-xs);
}

/* =====================
   Swap Button
   ===================== */
.swap-button {
    background: var(--gradient-secondary);
    border: none;
    border-radius: var(--border-radius-full);
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: var(--font-size-xl);
    color: white;
    transition: var(--transition-base);
    box-shadow: var(--shadow-md);
    align-self: center;
    margin-top: var(--spacing-8);
    position: relative;
    overflow: hidden;
}

.swap-button::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left var(--duration-500);
}

.swap-button:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-lg);
}

.swap-button:hover::before {
    left: 100%;
}

.swap-button:focus {
    outline: none;
    box-shadow: var(--shadow-lg), var(--focus-ring);
}

.swap-button:active {
    transform: scale(0.95);
}

.swap-button__icon {
    transition: var(--transition-base);
    font-weight: var(--font-weight-bold);
}

.swap-button:hover .swap-button__icon {
    transform: rotate(180deg);
}

/* =====================
   Result Actions & Buttons
   ===================== */
.result-actions {
    display: flex;
    gap: var(--spacing-4);
    justify-content: center;
    margin-bottom: var(--spacing-12);
    flex-wrap: wrap;
}

.btn {
    padding: var(--spacing-4) var(--spacing-6);
    border: none;
    border-radius: var(--border-radius-lg);
    cursor: pointer;
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-semibold);
    transition: var(--transition-base);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-2);
    text-decoration: none;
    min-height: 48px;
    position: relative;
    overflow: hidden;
    font-family: var(--font-family-base);
    line-height: var(--line-height-normal);
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.1), transparent);
    transition: left var(--duration-300);
}

.btn:hover::before {
    left: 100%;
}

.btn:focus {
    outline: none;
    box-shadow: var(--focus-ring);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

.btn:disabled::before {
    display: none;
}

.btn--primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn--primary:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn--secondary {
    background: #F8FAFC;
    color: var(--color-secondary);
    border: 2px solid #E2E8F0;
}

.btn--secondary:hover:not(:disabled) {
    background: var(--color-light);
    border-color: var(--color-primary);
    color: var(--color-primary);
    transform: translateY(-1px);
}

.btn--small {
    padding: var(--spacing-2) var(--spacing-4);
    font-size: var(--font-size-sm);
    min-height: 36px;
}

.btn__icon {
    font-size: var(--font-size-lg);
    flex-shrink: 0;
}

.btn__text {
    white-space: nowrap;
}

/* =====================
   Formula Display
   ===================== */
.formula {
    background: linear-gradient(135deg, #F8FAFC, #E2E8F0);
    border-radius: var(--border-radius-xl);
    padding: var(--spacing-6);
    border-left: 4px solid var(--color-primary);
    position: relative;
}

.formula::before {
    content: '📐';
    position: absolute;
    top: var(--spacing-4);
    right: var(--spacing-4);
    font-size: var(--font-size-lg);
    opacity: 0.5;
}

.formula__title {
    color: var(--color-secondary);
    margin-bottom: var(--spacing-3);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
}

.formula__content {
    font-family: var(--font-family-mono);
    background: white;
    padding: var(--spacing-4);
    border-radius: var(--border-radius-md);
    border: 1px solid #E2E8F0;
    font-size: var(--font-size-base);
    color: var(--color-secondary);
    line-height: var(--line-height-relaxed);
    word-break: break-all;
    box-shadow: var(--shadow-sm);
}

/* =====================
   History Section
   ===================== */
.history {
    background: white;
    border-radius: var(--border-radius-2xl);
    padding: var(--spacing-12);
    margin-bottom: var(--spacing-12);
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.history::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-secondary);
}

.history__header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-8);
    gap: var(--spacing-4);
}

.history h2 {
    color: var(--color-secondary);
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    margin: 0;
}

.history__list {
    max-height: 400px;
    overflow-y: auto;
    margin-bottom: var(--spacing-6);
    scrollbar-width: thin;
    scrollbar-color: var(--color-primary) #F1F5F9;
}

.history__list::-webkit-scrollbar {
    width: 6px;
}

.history__list::-webkit-scrollbar-track {
    background: #F1F5F9;
    border-radius: var(--border-radius-full);
}

.history__list::-webkit-scrollbar-thumb {
    background: var(--color-primary);
    border-radius: var(--border-radius-full);
}

.history__item {
    background: #F8FAFC;
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-4);
    margin-bottom: var(--spacing-3);
    border-left: 4px solid var(--color-primary);
    transition: var(--transition-base);
    position: relative;
    overflow: hidden;
}

.history__item::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(0, 173, 181, 0.05), transparent);
    transition: left var(--duration-300);
}

.history__item:hover {
    background: #E2E8F0;
    transform: translateX(4px);
    box-shadow: var(--shadow-sm);
}

.history__item:hover::before {
    left: 100%;
}

.history__empty {
    text-align: center;
    color: #64748B;
    padding: var(--spacing-16) var(--spacing-8);
    border: 2px dashed #CBD5E1;
    border-radius: var(--border-radius-xl);
    background: #F8FAFC;
}

.history__empty p {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-medium);
    margin-bottom: var(--spacing-2);
}

.history__empty small {
    font-size: var(--font-size-sm);
    opacity: 0.7;
}

/* =====================
   FAQ Section
   ===================== */
.faq {
    background: white;
    border-radius: var(--border-radius-2xl);
    padding: var(--spacing-12);
    margin-bottom: var(--spacing-12);
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.faq::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-primary);
}

.faq h2 {
    color: var(--color-secondary);
    margin-bottom: var(--spacing-8);
    font-size: var(--font-size-2xl);
    text-align: center;
    font-weight: var(--font-weight-bold);
}

.faq__item {
    border-bottom: 1px solid #E2E8F0;
    margin-bottom: var(--spacing-4);
    transition: var(--transition-base);
}

.faq__item:last-child {
    border-bottom: none;
    margin-bottom: 0;
}

.faq__item:hover {
    background: rgba(0, 173, 181, 0.02);
    border-radius: var(--border-radius-lg);
    margin: 0 calc(-1 * var(--spacing-4)) var(--spacing-4);
    padding: 0 var(--spacing-4);
}

.faq__question {
    width: 100%;
    background: none;
    border: none;
    padding: var(--spacing-6) 0;
    text-align: left;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    color: var(--color-secondary);
    transition: var(--transition-base);
    gap: var(--spacing-4);
    line-height: var(--line-height-snug);
}

.faq__question:hover {
    color: var(--color-primary);
}

.faq__question:focus {
    outline: none;
    color: var(--color-primary);
    box-shadow: inset var(--focus-ring);
    border-radius: var(--border-radius-md);
}

.faq__question-text {
    flex: 1;
    text-align: left;
}

.faq__icon {
    font-size: var(--font-size-xl);
    transition: var(--transition-base);
    font-weight: var(--font-weight-bold);
    flex-shrink: 0;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-primary);
    color: white;
    border-radius: var(--border-radius-full);
    font-size: var(--font-size-sm);
}

.faq__question[aria-expanded="true"] .faq__icon {
    transform: rotate(45deg);
    background: var(--color-error);
}

.faq__answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--duration-300) ease;
}

.faq__answer--open {
    max-height: 500px;
}

.faq__answer-content {
    padding-bottom: var(--spacing-6);
    animation: fadeIn var(--duration-300) ease;
}

.faq__answer p {
    margin-bottom: var(--spacing-3);
    color: #64748B;
    line-height: var(--line-height-relaxed);
    font-size: var(--font-size-base);
}

.faq__answer p:last-child {
    margin-bottom: 0;
}

.faq__answer strong {
    color: var(--color-secondary);
    font-weight: var(--font-weight-semibold);
}

@keyframes fadeIn {
    from { 
        opacity: 0; 
        transform: translateY(-8px); 
    }
    to { 
        opacity: 1; 
        transform: translateY(0); 
    }
}

/* =====================
   Footer
   ===================== */
.footer {
    background: var(--color-secondary);
    color: var(--color-light);
    padding: var(--spacing-8) 0;
    text-align: center;
    
}

.footer a {
    color: var(--color-accent);
    text-decoration: none;
    transition: var(--transition-base);
    font-weight: var(--font-weight-medium);
}

.footer a:hover {
    color: var(--color-primary);
    text-decoration: underline;
}

.footer a:focus {
    outline: none;
    box-shadow: var(--focus-ring);
    border-radius: var(--border-radius-sm);
    padding: var(--spacing-1) var(--spacing-2);
    margin: calc(-1 * var(--spacing-1)) calc(-1 * var(--spacing-2));
}

/* =====================
   Toast Notification
   ===================== */
.toast {

    opacity: 0;
    pointer-events: none;
    position: fixed;
    bottom: var(--spacing-6);
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--gradient-primary);
    color: white;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-2xl);
    z-index: var(--z-index-toast);
    transition: var(--transition-base);
    max-width: 90%;
    min-width: 300px;
    font-weight: var(--font-weight-medium);
    overflow: hidden;
}

.toast--show {
    opacity: 1;
    pointer-events: auto;
    transform: translateX(-50%) translateY(0);
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.toast--hide {
    opacity: 0;
    transform: translateX(-50%) translateY(100px);
    pointer-events: none;
}

.toast--success {
    background: var(--gradient-success);
}

.toast--error {
    background: var(--gradient-error);
}

.toast--info {
    background: linear-gradient(135deg, var(--color-info), #2563EB);
}

.toast--warning {
    background: linear-gradient(135deg, var(--color-warning), #D97706);
}

.toast__content {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
    padding: var(--spacing-4) var(--spacing-6);
}

.toast__icon {
    font-size: var(--font-size-lg);
    flex-shrink: 0;
}

.toast__message {
    flex: 1;
    line-height: var(--line-height-snug);
}

.toast__close {
    background: none;
    border: none;
    color: white;
    cursor: pointer;
    padding: var(--spacing-2);
    margin: var(--spacing-2) var(--spacing-2) var(--spacing-2) 0;
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-lg);
    line-height: 1;
    transition: var(--transition-fast);
    opacity: 0.8;
}

.toast__close:hover {
    opacity: 1;
    background: rgba(255, 255, 255, 0.1);
}

.toast__close:focus {
    outline: none;
    opacity: 1;
    background: rgba(255, 255, 255, 0.2);
}

/* =====================
   Install PWA Button
   ===================== */
.install-button {
    position: fixed;
    bottom: var(--spacing-6);
    right: var(--spacing-6);
    background: var(--gradient-primary);
    color: white;
    border: none;
    border-radius: var(--border-radius-full);
    padding: var(--spacing-4);
    box-shadow: var(--shadow-xl);
    cursor: pointer;
    transition: var(--transition-base);
    z-index: var(--z-index-fixed);
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    font-weight: var(--font-weight-semibold);
    font-size: var(--font-size-sm);
}

.install-button:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-2xl);
}

.install-button:focus {
    outline: none;
    box-shadow: var(--shadow-xl), var(--focus-ring);
}

.install-button__icon {
    font-size: var(--font-size-lg);
}

/* =====================
   Responsive Design
   ===================== */

/* Large screens */
@media (min-width: 1536px) {
    .container {
        max-width: 1400px;
    }
    
    .header__title {
        font-size: var(--font-size-5xl);
    }
    
    .converter__form {
        gap: var(--spacing-12);
    }
}

/* Desktop */
@media (max-width: 1024px) {
    .container {
        padding: 0 var(--spacing-6);
    }
    
    .converter__form {
        gap: var(--spacing-6);
    }
    
    .header__title {
        font-size: var(--font-size-3xl);
    }
}

/* Tablet */
@media (max-width: 768px) {
    .container {
        padding: 0 var(--spacing-4);
    }
    
    .header {
        padding: var(--spacing-6) 0;
    }
    
    .header__content {
        flex-direction: column;
        gap: var(--spacing-4);
        text-align: center;
    }
    
    .header__title {
        font-size: var(--font-size-2xl);
    }
    
    .header__subtitle {
        font-size: var(--font-size-base);
    }
    
    .main {
        padding: var(--spacing-8) 0;
    }
    
    .tabs {
        grid-template-columns: 1fr;
        gap: var(--spacing-1);
    }
    
    .tabs::before {
        width: calc(100% - var(--spacing-2));
        height: calc(33.333% - var(--spacing-1));
        transform: translateY(0);
    }
    
    .tabs[data-active="volume"]::before {
        transform: translateY(100%);
    }
    
    .tabs[data-active="temperature"]::before {
        transform: translateY(200%);
    }
    
    .tabs__button {
        padding: var(--spacing-4);
        justify-content: flex-start;
        gap: var(--spacing-3);
    }
    
    .converter__form {
        grid-template-columns: 1fr;
        gap: var(--spacing-6);
    }
    
    .swap-button {
        justify-self: center;
        transform: rotate(90deg);
        margin: var(--spacing-4) 0;
    }
    
    .swap-button:hover .swap-button__icon {
        transform: rotate(270deg);
    }
    
    .input-wrapper {
        gap: var(--spacing-3);
    }
    
    .result-actions {
        flex-direction: column;
        align-items: stretch;
        gap: var(--spacing-3);
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    .converter,
    .history,
    .faq {
        padding: var(--spacing-8);
        margin-bottom: var(--spacing-8);
    }
    
    .history__header {
        flex-direction: column;
        align-items: stretch;
        gap: var(--spacing-4);
    }
    
    .faq__question {
        font-size: var(--font-size-base);
        padding: var(--spacing-4) 0;
    }
    
    .install-button {
        bottom: var(--spacing-4);
        right: var(--spacing-4);
        padding: var(--spacing-3);
    }
    
    .install-button__text {
        display: none;
    }
}

/* Mobile */
@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-3);
    }
    
    .header {
        padding: var(--spacing-4) 0;
    }
    
    .header__title {
        font-size: var(--font-size-xl);
    }
    
    .header__subtitle {
        font-size: var(--font-size-sm);
    }
    
    .main {
        padding: var(--spacing-6) 0;
    }
    
    .converter,
    .history,
    .faq {
        margin-bottom: var(--spacing-6);
        padding: var(--spacing-6);
        border-radius: var(--border-radius-xl);
    }
    
    .converter__header h2 {
        font-size: var(--font-size-xl);
       
    }

    
    .converter__header p {
        font-size: var(--font-size-base);
    }
    
    .theme-toggle {
        width: 44px;
        height: 44px;
    }
    
    .theme-toggle__icon {
        font-size: var(--font-size-base);
    }
    
    .swap-button {
        width: 48px;
        height: 48px;
        font-size: var(--font-size-lg);
    }
    
    .tabs__button {
        padding: var(--spacing-3);
        font-size: var(--font-size-sm);
        gap: var(--spacing-2);
    }
    
    .tabs__icon {
        font-size: var(--font-size-base);
    }
    
    .input-field__input,
    .select-field {
        padding: var(--spacing-3);
        font-size: var(--font-size-sm);
        min-height: 44px;
    }
    
    .btn {
        padding: var(--spacing-3) var(--spacing-4);
        font-size: var(--font-size-sm);
        min-height: 44px;
    }
    
    .btn__icon {
        font-size: var(--font-size-base);
    }
    
    .toast {
        min-width: 280px;
        bottom: var(--spacing-4);
    }
    
    .toast__content {
        padding: var(--spacing-3) var(--spacing-4);
    }
}

/* Extra small devices */
@media (max-width: 320px) {
    .container {
        padding: 0 var(--spacing-2);
    }
    
    .converter,
    .history,
    .faq {
        padding: var(--spacing-4);
    }
    
    .tabs__button {
        padding: var(--spacing-2);
        font-size: var(--font-size-xs);
    }
    
    .input-field__input,
    .select-field {
        padding: var(--spacing-2-5);
        font-size: var(--font-size-xs);
    }
    
    .btn {
        padding: var(--spacing-2-5) var(--spacing-3);
        font-size: var(--font-size-xs);
        min-height: 40px;
    }
    
    .toast {
        min-width: 260px;
    }
}

/* Print Styles */
@media print {
    .header,
    .tabs,
    .result-actions,
    .history,
    .footer,
    .toast,
    .install-button,
    .theme-toggle,
    .loading-screen {
        display: none !important;
    }
    
    .converter {
        box-shadow: none;
        border: 1px solid #ccc;
        break-inside: avoid;
        page-break-inside: avoid;
    }
    
    .converter::before {
        display: none;
    }
    
    body {
        background: white !important;
        color: black !important;
        font-size: 12pt;
        line-height: 1.4;
    }
    
    .main {
        padding: 0;
    }
    
    .container {
        max-width: none;
        padding: 0;
    }
    
    .formula__content {
        border: 1px solid #ccc;
        background: #f9f9f9;
    }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
    :root {
        --color-primary: #0066cc;
        --color-secondary: #000000;
        --color-dark: #000000;
        --color-light: #ffffff;
        --color-accent: #ff6600;
        --color-success: #008000;
        --color-error: #cc0000;
        --color-warning: #ff8800;
        --color-info: #0066cc;
    }
    
    .btn--secondary {
        border-width: 3px;
    }
    
    .input-field__input,
    .select-field {
        border-width: 3px;
    }
    
    .tabs__button:focus,
    .btn:focus,
    .input-field__input:focus,
    .select-field:focus {
        outline: 3px solid var(--color-primary);
        outline-offset: 2px;
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
    
    .header::before {
        animation: none;
    }
    
    .loading-spinner {
        animation: none;
        border: 3px solid #ccc;
        border-top: 3px solid var(--color-primary);
    }
    
    .swap-button:hover .swap-button__icon {
        transform: none;
    }
    
    .tabs::before {
        transition: none;
    }
}

/* Focus Styles for Accessibility */
*:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* Loading States */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

.loading .input-field__loading {
    opacity: 1;
}

/* Utility Classes */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.text-center {
    text-align: center;
}

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

.hidden {
    display: none;
}

.visible {
    display: block;
}

/* Animation Classes */
.fade-in {
    animation: fadeIn var(--duration-300) ease;
}

.slide-up {
    animation: slideUp var(--duration-300) ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.bounce {
    animation: bounce var(--duration-500) ease;
}

@keyframes bounce {
    0%, 20%, 53%, 80%, 100% {
        transform: translate3d(0, 0, 0);
    }
    40%, 43% {
        transform: translate3d(0, -8px, 0);
    }
    70% {
        transform: translate3d(0, -4px, 0);
    }
    90% {
        transform: translate3d(0, -2px, 0);
    }
}

/* Dark mode specific adjustments */
[data-theme="dark"] .converter,
[data-theme="dark"] .history,
[data-theme="dark"] .faq {
    background: #2D3748;
    color: var(--color-dark);
}

[data-theme="dark"] .input-field__input,
[data-theme="dark"] .select-field {
    background: #1A202C;
    border-color: #4A5568;
    color: var(--color-dark);
}

[data-theme="dark"] .input-field__input:focus,
[data-theme="dark"] .select-field:focus {
    border-color: var(--color-primary);
    background: #2D3748;
}

[data-theme="dark"] .converter__header h2 {
    color: #F7FAFC !important; /* Branco quase puro para títulos */
}
[data-theme="dark"] .converter__header p {
    color: #E0E6ED !important; /* Cinza claro para subtítulos */
}

[data-theme="dark"] .faq h2 {
    color: #E0E6ED !important; /* Cinza claro para subtítulos */
}
[data-theme="dark"] .faq__answer-content p {
    color: #E0E6ED !important; /* Cinza claro para subtítulos */
}

[data-theme="dark"] .faq__item .faq__question {
    color: #E0E6ED !important; /* Cinza claro para subtítulos */
}

[data-theme="dark"] .container small {
    color: #E0E6ED !important; /* Cinza claro para subtítulos */
}
[data-theme="dark"] .input-group__label {
    color: #E0E6ED !important; /* Cinza claro para subtítulos */
}


[data-theme="dark"] .input-field__input--readonly {
    background: #4A5568;
    color: var(--color-dark);
}

[data-theme="dark"] .btn--secondary {
    background: #4A5568;
    color: var(--color-dark);
    border-color: #718096;
}

[data-theme="dark"] .btn--secondary:hover:not(:disabled) {
    background: #718096;
    border-color: var(--color-primary);
}

[data-theme="dark"] .formula {
    background: linear-gradient(135deg, #2D3748, #4A5568);
}

[data-theme="dark"] .formula__content {
    background: #1A202C;
    border-color: #4A5568;
    color: var(--color-dark);
}

[data-theme="dark"] .history__item {
    background: #4A5568;
    color: var(--color-dark);
}

[data-theme="dark"] .history__item:hover {
    background: #718096;
}

[data-theme="dark"] .history__empty {
    background: #4A5568;
    border-color: #718096;
    color: #A0AEC0;
}

[data-theme="dark"] .tabs {
    background: #2D3748;
}

[data-theme="dark"] .input-error {
    color: #FC8181;
}

/* Performance optimizations */
.converter,
.history,
.faq {
    contain: layout style paint;
}

.tabs__button,
.btn,
.swap-button {
    will-change: transform;
}

.toast {
    will-change: transform;
}

/* GPU acceleration for animations */
.swap-button,
.btn,
.tabs::before,
.theme-toggle {
    transform: translateZ(0);
}