/**
 * Build Master - Construction Math Game Styles
 * Author: Senior Frontend Engineer
 * Mobile-First Responsive Design
 */

/* ========================================
   CSS RESET & VARIABLES
   ======================================== */

:root {
    /* Color Palette - Construction Theme */
    --color-primary: #FF6B35;
    --color-primary-dark: #E55A2B;
    --color-secondary: #FFB84D;
    --color-accent: #4ECDC4;
    --color-success: #52C41A;
    --color-error: #F5222D;
    --color-warning: #FAAD14;
    
    /* Sky & Background */
    --color-sky: #87CEEB;
    --color-sky-gradient: linear-gradient(180deg, #87CEEB 0%, #B0E0E6 100%);
    --color-ground: #8B7355;
    --color-grass: #7CB342;
    
    /* Building Colors */
    --color-building-1: #D32F2F;
    --color-building-2: #1976D2;
    --color-building-3: #388E3C;
    --color-building-4: #F57C00;
    --color-building-5: #7B1FA2;
    --color-building-6: #0097A7;
    
    /* Neutrals */
    --color-white: #FFFFFF;
    --color-black: #000000;
    --color-gray-50: #FAFAFA;
    --color-gray-100: #F5F5F5;
    --color-gray-200: #EEEEEE;
    --color-gray-300: #E0E0E0;
    --color-gray-400: #BDBDBD;
    --color-gray-500: #9E9E9E;
    --color-gray-600: #757575;
    --color-gray-700: #616161;
    --color-gray-800: #424242;
    --color-gray-900: #212121;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
    
    /* Typography */
    --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-md: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.5rem;
    --font-size-xxl: 2rem;
    --font-size-xxxl: 2.5rem;
    
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    /* Borders & Shadows */
    --border-radius-sm: 0.25rem;
    --border-radius-md: 0.5rem;
    --border-radius-lg: 1rem;
    --border-radius-xl: 1.5rem;
    
    --box-shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --box-shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --box-shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --box-shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Z-index layers */
    --z-background: -1;
    --z-base: 1;
    --z-dropdown: 100;
    --z-modal: 1000;
    --z-tooltip: 1100;
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-md);
    line-height: 1.6;
    color: var(--color-gray-900);
    background: var(--color-sky-gradient);
    min-height: 100vh;
    overflow-x: hidden;
    position: relative;
}

/* Visually hidden but accessible */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ========================================
   SKY BACKGROUND
   ======================================== */

.sky-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: var(--z-background);
    background: var(--color-sky-gradient);
    overflow: hidden;
}

.sun {
    position: absolute;
    top: 10%;
    right: 15%;
    width: 80px;
    height: 80px;
    background: radial-gradient(circle, #FFD700 0%, #FFA500 100%);
    border-radius: 50%;
    box-shadow: 0 0 40px rgba(255, 215, 0, 0.6);
    animation: sunPulse 4s ease-in-out infinite;
}

@keyframes sunPulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.cloud {
    position: absolute;
    background: rgba(255, 255, 255, 0.8);
    border-radius: 100px;
    opacity: 0.9;
    animation: cloudFloat 30s linear infinite;
}

.cloud::before,
.cloud::after {
    content: '';
    position: absolute;
    background: rgba(255, 255, 255, 0.8);
    border-radius: 100px;
}

.cloud-1 {
    width: 100px;
    height: 40px;
    top: 15%;
    left: -100px;
    animation-duration: 35s;
}

.cloud-1::before {
    width: 50px;
    height: 50px;
    top: -25px;
    left: 10px;
}

.cloud-1::after {
    width: 60px;
    height: 35px;
    top: -15px;
    right: 10px;
}

.cloud-2 {
    width: 120px;
    height: 45px;
    top: 25%;
    left: -120px;
    animation-duration: 40s;
    animation-delay: 5s;
}

.cloud-2::before {
    width: 55px;
    height: 55px;
    top: -28px;
    left: 15px;
}

.cloud-2::after {
    width: 65px;
    height: 40px;
    top: -18px;
    right: 15px;
}

.cloud-3 {
    width: 90px;
    height: 35px;
    top: 35%;
    left: -90px;
    animation-duration: 32s;
    animation-delay: 10s;
}

.cloud-3::before {
    width: 45px;
    height: 45px;
    top: -22px;
    left: 12px;
}

.cloud-3::after {
    width: 50px;
    height: 30px;
    top: -12px;
    right: 12px;
}

.cloud-4 {
    width: 110px;
    height: 42px;
    top: 45%;
    left: -110px;
    animation-duration: 38s;
    animation-delay: 15s;
}

.cloud-4::before {
    width: 52px;
    height: 52px;
    top: -26px;
    left: 14px;
}

.cloud-4::after {
    width: 58px;
    height: 38px;
    top: -16px;
    right: 14px;
}

@keyframes cloudFloat {
    from {
        transform: translateX(0);
    }
    to {
        transform: translateX(calc(100vw + 150px));
    }
}

/* ========================================
   GAME CONTAINER
   ======================================== */

.game-container {
    position: relative;
    z-index: var(--z-base);
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-md);
    min-height: 100vh;
}

/* ========================================
   HEADER
   ======================================== */

.game-header {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    border: 2px solid rgba(0, 102, 204, 0.1);
}

.game-title {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.title-icon {
    font-size: var(--font-size-xxl);
    animation: bounce 2s ease-in-out infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.resources-panel {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    justify-content: center;
}

.resource-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    background: var(--color-gray-100);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
}

.resource-item.score-display {
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    color: var(--color-white);
}

.resource-icon {
    font-size: var(--font-size-lg);
}

.resource-value {
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
}

.score-display .resource-value {
    color: var(--color-white);
}

/* ========================================
   SCREENS
   ======================================== */

.screen {
    display: none;
    animation: fadeIn 0.5s ease;
}

.screen.active {
    display: block;
}

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

/* ========================================
   WELCOME SCREEN
   ======================================== */

.welcome-content {
    background: var(--color-white);
    border-radius: var(--border-radius-xl);
    padding: var(--spacing-xxl) var(--spacing-xl);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
    max-width: 900px;
    margin: 0 auto;
    border: 2px solid rgba(0, 102, 204, 0.1);
}

.welcome-hero {
    margin-bottom: var(--spacing-xl);
    display: flex;
    justify-content: center;
}

.blueprint {
    position: relative;
    width: 200px;
    height: 200px;
    background: linear-gradient(135deg, #0066CC 0%, #004C99 100%);
    border-radius: var(--border-radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--box-shadow-lg);
    overflow: hidden;
}

.blueprint-lines {
    position: absolute;
    width: 100%;
    height: 100%;
    background-image: 
        repeating-linear-gradient(0deg, transparent, transparent 19px, rgba(255,255,255,0.1) 19px, rgba(255,255,255,0.1) 20px),
        repeating-linear-gradient(90deg, transparent, transparent 19px, rgba(255,255,255,0.1) 19px, rgba(255,255,255,0.1) 20px);
}

.blueprint-title {
    position: relative;
    color: var(--color-white);
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    text-align: center;
    z-index: 1;
}

.welcome-title {
    font-size: var(--font-size-xxl);
    font-weight: var(--font-weight-bold);
    color: var(--color-gray-900);
    text-align: center;
    margin-bottom: var(--spacing-md);
}

.welcome-description {
    font-size: var(--font-size-lg);
    color: var(--color-gray-600);
    text-align: center;
    margin-bottom: var(--spacing-xl);
    line-height: 1.8;
}

.settings-panel {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

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

.setting-title {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    color: var(--color-gray-800);
    text-align: center;
}

.operation-buttons,
.difficulty-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-md);
}

.btn-operation,
.btn-difficulty {
    padding: var(--spacing-lg);
    font-size: var(--font-size-md);
    font-weight: var(--font-weight-semibold);
    border: 2px solid transparent;
    border-radius: var(--border-radius-lg);
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    background: var(--color-gray-100);
    color: var(--color-gray-800);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.btn-operation:hover,
.btn-difficulty:hover {
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
    background: var(--color-gray-200);
}

.btn-operation.active,
.btn-difficulty.active {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--color-white);
}

.operation-symbol,
.difficulty-icon {
    font-size: var(--font-size-xxl);
}

.operation-name,
.difficulty-name {
    font-weight: var(--font-weight-semibold);
}

.difficulty-range {
    font-size: var(--font-size-xs);
    opacity: 0.8;
}

/* ========================================
   BUTTONS
   ======================================== */

.btn-primary,
.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    font-family: inherit;
    font-size: var(--font-size-md);
    font-weight: var(--font-weight-semibold);
    border: none;
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
    color: var(--color-white);
    box-shadow: var(--box-shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--box-shadow-lg);
}

.btn-primary:active {
    transform: translateY(0);
}

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

.btn-secondary {
    background: var(--color-white);
    color: var(--color-primary);
    border: 2px solid var(--color-primary);
}

.btn-secondary:hover {
    background: var(--color-gray-50);
    transform: translateY(-2px);
}

.btn-large {
    padding: var(--spacing-lg) var(--spacing-xxl);
    font-size: var(--font-size-lg);
}

.btn-icon {
    font-size: 1.2em;
}

/* ========================================
   GAME SCREEN
   ======================================== */

.construction-site {
    position: relative;
    background: var(--color-sky-gradient);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl) var(--spacing-md);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--box-shadow-lg);
    min-height: 400px;
    overflow: hidden;
}

.skyline {
    display: flex;
    align-items: flex-end;
    justify-content: center;
    gap: var(--spacing-sm);
    min-height: 250px;
    flex-wrap: wrap;
    padding-bottom: var(--spacing-md);
}

.building {
    position: relative;
    width: 60px;
    background: var(--building-color, var(--color-building-1));
    border-radius: var(--border-radius-sm) var(--border-radius-sm) 0 0;
    box-shadow: var(--box-shadow-md);
    animation: buildingRise 0.8s ease-out;
    transform-origin: bottom;
}

@keyframes buildingRise {
    from {
        transform: scaleY(0);
        opacity: 0;
    }
    to {
        transform: scaleY(1);
        opacity: 1;
    }
}

.building::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        repeating-linear-gradient(0deg, transparent 0px, transparent 18px, rgba(0,0,0,0.1) 18px, rgba(0,0,0,0.1) 20px),
        repeating-linear-gradient(90deg, transparent 0px, transparent 18px, rgba(0,0,0,0.1) 18px, rgba(0,0,0,0.1) 20px);
}

.building-emoji {
    position: absolute;
    top: -30px;
    left: 50%;
    transform: translateX(-50%);
    font-size: var(--font-size-xxl);
    animation: emojiFloat 2s ease-in-out infinite;
}

@keyframes emojiFloat {
    0%, 100% { transform: translateX(-50%) translateY(0); }
    50% { transform: translateX(-50%) translateY(-5px); }
}

/* Crane */
.crane-container {
    position: absolute;
    right: 5%;
    bottom: 60px;
    z-index: 10;
}

.crane {
    position: relative;
    width: 150px;
    height: 200px;
}

.crane-tower {
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 15px;
    height: 120px;
    background: linear-gradient(180deg, #FFD700 0%, #FFA500 100%);
    border-radius: var(--border-radius-sm);
}

.crane-tower::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 30px;
    height: 15px;
    background: #8B7355;
    border-radius: var(--border-radius-sm);
}

.crane-arm {
    position: absolute;
    top: 10px;
    left: 0;
    width: 100%;
    height: 10px;
    background: linear-gradient(90deg, #E55A2B 0%, var(--color-primary) 100%);
    border-radius: var(--border-radius-sm);
    transform-origin: 50% 50%;
    animation: craneSwing 4s ease-in-out infinite;
}

@keyframes craneSwing {
    0%, 100% { transform: rotate(-2deg); }
    50% { transform: rotate(2deg); }
}

.crane-cable {
    position: absolute;
    top: 20px;
    right: 20px;
    width: 2px;
    height: 60px;
    background: var(--color-gray-800);
    animation: cableMove 4s ease-in-out infinite;
}

@keyframes cableMove {
    0%, 100% { height: 60px; }
    50% { height: 80px; }
}

.crane-hook {
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 12px;
    height: 8px;
    background: var(--color-gray-700);
    border-radius: 0 0 4px 4px;
}

/* Ground */
.ground {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 60px;
    background: var(--color-ground);
    border-radius: 0 0 var(--border-radius-lg) var(--border-radius-lg);
}

.ground-grass {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 10px;
    background: var(--color-grass);
    border-radius: var(--border-radius-sm) var(--border-radius-sm) 0 0;
}

.ground-grass::before {
    content: '🌱 🌿 🌱 🌿 🌱 🌿 🌱 🌿 🌱 🌿 🌱 🌿';
    position: absolute;
    top: -8px;
    left: 0;
    right: 0;
    font-size: var(--font-size-xs);
    text-align: center;
    letter-spacing: 10px;
}

/* Building Progress Panel */
.building-progress-panel {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--box-shadow-md);
}

.current-building-info {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.building-name {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    color: var(--color-gray-900);
}

.current-building-emoji {
    font-size: var(--font-size-xxxl);
}

.progress-bar-container {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.progress-label {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    color: var(--color-gray-600);
    text-align: center;
}

.progress-bar {
    position: relative;
    width: 100%;
    height: 30px;
    background: var(--color-gray-200);
    border-radius: var(--border-radius-md);
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
    border-radius: var(--border-radius-md);
    transition: width var(--transition-slow);
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding-right: var(--spacing-sm);
}

.progress-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-bold);
    color: var(--color-gray-900);
    z-index: 1;
}

/* Question Panel */
.question-panel {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--box-shadow-lg);
}

.question-display {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.question-icon {
    font-size: var(--font-size-xxxl);
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.1); }
}

.question-text {
    font-size: var(--font-size-xxl);
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
    text-align: center;
}

.answer-section {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.input-group {
    display: flex;
    gap: var(--spacing-md);
}

.answer-input {
    flex: 1;
    padding: var(--spacing-md) var(--spacing-lg);
    font-family: inherit;
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    text-align: center;
    border: 2px solid var(--color-gray-300);
    border-radius: var(--border-radius-md);
    transition: all var(--transition-base);
}

.answer-input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(255, 107, 53, 0.1);
}

.answer-input.correct {
    border-color: var(--color-success);
    background: rgba(82, 196, 26, 0.05);
}

.answer-input.incorrect {
    border-color: var(--color-error);
    background: rgba(245, 34, 45, 0.05);
    animation: shake 0.5s ease;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
    20%, 40%, 60%, 80% { transform: translateX(5px); }
}

.btn-submit {
    padding: var(--spacing-md) var(--spacing-xl);
    background: linear-gradient(135deg, var(--color-success), #389E0D);
    color: var(--color-white);
    border: none;
    border-radius: var(--border-radius-md);
    font-family: inherit;
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-bold);
    cursor: pointer;
    transition: all var(--transition-base);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    box-shadow: var(--box-shadow-md);
}

.btn-submit:hover {
    transform: translateY(-2px);
    box-shadow: var(--box-shadow-lg);
}

.btn-submit:active {
    transform: translateY(0);
}

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

.feedback-message {
    min-height: 30px;
    padding: var(--spacing-md);
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-md);
    font-weight: var(--font-weight-medium);
    text-align: center;
    opacity: 0;
    transform: translateY(-10px);
    transition: all var(--transition-base);
}

.feedback-message.show {
    opacity: 1;
    transform: translateY(0);
}

.feedback-message.success {
    background: rgba(82, 196, 26, 0.1);
    color: var(--color-success);
    border: 2px solid var(--color-success);
}

.feedback-message.error {
    background: rgba(245, 34, 45, 0.1);
    color: var(--color-error);
    border: 2px solid var(--color-error);
}

.feedback-message.turbo {
    background: linear-gradient(135deg, var(--color-secondary), var(--color-primary));
    color: var(--color-white);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-bold);
}

/* Streak Indicator */
.streak-indicator {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
    padding: var(--spacing-sm) var(--spacing-md);
    background: linear-gradient(135deg, #FF4500, #FF6347);
    color: var(--color-white);
    border-radius: var(--border-radius-md);
    font-weight: var(--font-weight-bold);
    opacity: 0;
    transform: scale(0.8);
    transition: all var(--transition-base);
}

.streak-indicator.active {
    opacity: 1;
    transform: scale(1);
}

.streak-icon {
    font-size: var(--font-size-xl);
    animation: fireFlicker 1s ease-in-out infinite;
}

@keyframes fireFlicker {
    0%, 100% { transform: scale(1) rotate(-5deg); }
    50% { transform: scale(1.1) rotate(5deg); }
}

/* Game Stats */
.game-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.stat-card {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--box-shadow-md);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    transition: transform var(--transition-base);
}

.stat-card:hover {
    transform: translateY(-2px);
}

.stat-icon {
    font-size: var(--font-size-xxxl);
}

.stat-label {
    font-size: var(--font-size-sm);
    color: var(--color-gray-600);
    font-weight: var(--font-weight-medium);
}

.stat-value {
    font-size: var(--font-size-xxl);
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
}

/* ========================================
   ACHIEVEMENT SCREEN
   ======================================== */

.achievement-content {
    background: var(--color-white);
    border-radius: var(--border-radius-xl);
    padding: var(--spacing-xxl);
    box-shadow: var(--box-shadow-xl);
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

.achievement-animation {
    margin-bottom: var(--spacing-xl);
}

.building-complete-icon {
    font-size: 120px;
    animation: celebrationBounce 1s ease-in-out;
}

@keyframes celebrationBounce {
    0%, 100% { transform: scale(1) rotate(0deg); }
    25% { transform: scale(1.2) rotate(-10deg); }
    50% { transform: scale(1.1) rotate(10deg); }
    75% { transform: scale(1.15) rotate(-5deg); }
}

.achievement-title {
    font-size: var(--font-size-xxxl);
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
}

.achievement-message {
    font-size: var(--font-size-lg);
    color: var(--color-gray-700);
    margin-bottom: var(--spacing-xl);
    line-height: 1.8;
}

.achievement-stats {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
    background: var(--color-gray-100);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius-lg);
}

.achievement-stat {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: var(--font-size-lg);
}

.achievement-stat .stat-label {
    color: var(--color-gray-700);
    font-weight: var(--font-weight-medium);
}

.achievement-stat .stat-value {
    color: var(--color-primary);
    font-weight: var(--font-weight-bold);
    font-size: var(--font-size-xl);
}

.achievement-buttons {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

/* ========================================
   RESULTS SCREEN
   ======================================== */

.results-content {
    background: var(--color-white);
    border-radius: var(--border-radius-xl);
    padding: var(--spacing-xxl);
    box-shadow: var(--box-shadow-xl);
    max-width: 900px;
    margin: 0 auto;
}

.results-header {
    margin-bottom: var(--spacing-xxl);
}

.results-title {
    font-size: var(--font-size-xxxl);
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.city-showcase {
    background: var(--color-sky-gradient);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    min-height: 300px;
    display: flex;
    align-items: flex-end;
    justify-content: center;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
    box-shadow: inset 0 2px 10px rgba(0,0,0,0.1);
}

.results-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xxl);
}

.result-card {
    background: linear-gradient(135deg, var(--color-gray-50), var(--color-white));
    border: 2px solid var(--color-gray-200);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    transition: all var(--transition-base);
}

.result-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--box-shadow-lg);
    border-color: var(--color-primary);
}

.result-icon {
    font-size: var(--font-size-xxxl);
}

.result-label {
    font-size: var(--font-size-sm);
    color: var(--color-gray-600);
    font-weight: var(--font-weight-medium);
    text-align: center;
}

.result-value {
    font-size: var(--font-size-xxl);
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
}

.results-buttons {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

/* ========================================
   SOUND INDICATOR
   ======================================== */

.sound-indicator {
    position: fixed;
    top: 20px;
    right: 20px;
    background: var(--color-white);
    padding: var(--spacing-md);
    border-radius: 50%;
    box-shadow: var(--box-shadow-lg);
    font-size: var(--font-size-xxl);
    z-index: var(--z-tooltip);
    opacity: 0;
    transform: scale(0.5);
    transition: all var(--transition-fast);
}

.sound-indicator.show {
    opacity: 1;
    transform: scale(1);
    animation: soundPulse 0.5s ease;
}

@keyframes soundPulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.2); }
}

/* ========================================
   RESPONSIVE DESIGN
   ======================================== */

@media (min-width: 768px) {
    .game-header {
        flex-direction: row;
        justify-content: space-between;
        align-items: center;
    }

    .game-title {
        font-size: var(--font-size-xxl);
    }

    .welcome-title {
        font-size: var(--font-size-xxxl);
    }

    .input-group {
        max-width: 600px;
        margin: 0 auto;
    }

    .achievement-buttons,
    .results-buttons {
        flex-direction: row;
        justify-content: center;
    }
}

@media (min-width: 1024px) {
    .game-container {
        padding: var(--spacing-xl);
    }

    .construction-site {
        min-height: 500px;
    }

    .skyline {
        min-height: 350px;
    }

    .building {
        width: 80px;
    }
}

/* ========================================
   ACCESSIBILITY
   ======================================== */

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus styles */
button:focus-visible,
input:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    .btn-primary,
    .btn-secondary {
        border: 2px solid currentColor;
    }
}

/* ========================================
   FOOTER
   ======================================== */
.game-footer {
    text-align: center;
    padding: var(--spacing-md);
    color: white;
    font-size: var(--font-size-sm);
}
.game-footer p { color: white; }
.game-footer a { color: white; text-decoration: none; font-weight: bold; }
.game-footer a:hover { color: var(--color-secondary); text-decoration: underline; }