/* ===================================
   FlipTheCoin - CSS Styles
   Modern, glassmorphism UI with dark theme
   =================================== */

/* ===== CSS Custom Properties ===== */
:root {
    /* Colors */
    --color-primary: #66ccff;
    --color-primary-dark: #3399cc;
    --color-primary-light: #99ddff;
    --color-secondary: #8866ff;
    --color-success: #66ff99;
    --color-warning: #ffcc66;
    --color-danger: #ff6666;

    /* Background */
    --bg-primary: #0a0e1a;
    --bg-secondary: #151b2e;
    --bg-tertiary: #1f2842;

    /* Glass effect */
    --glass-bg: rgba(31, 40, 66, 0.7);
    --glass-border: rgba(102, 204, 255, 0.2);
    --glass-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);

    /* Text */
    --text-primary: #ffffff;
    --text-secondary: #a0aec0;
    --text-muted: #718096;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Border radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;

    /* Z-index */
    --z-modal: 1000;
    --z-overlay: 999;
    --z-header: 100;
    --z-result: 50;
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    /* Support for notched devices */
    padding: env(safe-area-inset-top, 0) env(safe-area-inset-right, 0) env(safe-area-inset-bottom, 0) env(safe-area-inset-left, 0);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

/* Animated background stars effect */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image:
        radial-gradient(2px 2px at 20% 30%, white, transparent),
        radial-gradient(2px 2px at 60% 70%, white, transparent),
        radial-gradient(1px 1px at 50% 50%, white, transparent),
        radial-gradient(1px 1px at 80% 10%, white, transparent),
        radial-gradient(2px 2px at 90% 60%, white, transparent);
    background-size: 200% 200%;
    animation: twinkle 20s infinite;
    opacity: 0.3;
    pointer-events: none;
    z-index: 0;
}

@keyframes twinkle {
    0%, 100% { opacity: 0.3; }
    50% { opacity: 0.5; }
}

/* ===== Loading Screen ===== */
.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--bg-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    transition: opacity var(--transition-slow), visibility var(--transition-slow);
}

.loading-screen.hidden {
    opacity: 0;
    visibility: hidden;
}

.loading-content {
    text-align: center;
    max-width: 300px;
}

.loading-spinner {
    width: clamp(48px, 10vw, 60px);
    height: clamp(48px, 10vw, 60px);
    margin: 0 auto var(--spacing-lg);
    border: 4px solid rgba(102, 204, 255, 0.2);
    border-top-color: var(--color-primary);
    border-radius: var(--radius-full);
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.loading-title {
    font-size: clamp(1.5rem, 5vw, 2rem);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.loading-text {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
}

.loading-bar {
    width: 100%;
    height: 4px;
    background: rgba(102, 204, 255, 0.2);
    border-radius: var(--radius-full);
    overflow: hidden;
    margin-bottom: var(--spacing-sm);
}

.loading-progress {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
    border-radius: var(--radius-full);
    transition: width var(--transition-normal);
    width: 0;
}

.loading-percent {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* ===== Main App Container ===== */
.app-container {
    position: relative;
    min-height: 100vh;
    padding: var(--spacing-md);
    z-index: 1;
    overflow-x: hidden; /* Prevent horizontal scroll on mobile */
    max-width: 100vw; /* Ensure container doesn't exceed viewport */
}

/* ===== Header ===== */
.app-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) 0;
    margin-bottom: var(--spacing-lg);
    position: relative;
    z-index: var(--z-header);
}

.app-title {
    font-size: clamp(1.25rem, 4vw, 1.75rem);
    font-weight: 700;
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* ===== Main Content ===== */
.main-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
    max-width: 1400px;
    margin: 0 auto;
    width: 100%; /* Ensure it doesn't exceed container */
}

/* ===== Glass Panel Effect ===== */
.glass-panel {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--glass-shadow);
    padding: var(--spacing-lg);
}

/* ===== Coin Container ===== */
.coin-container {
    position: relative;
    width: 100%;
    max-width: 100%; /* Prevent overflow */
    height: calc(100vh - 200px);
    min-height: 400px;
    max-height: 1200px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
    cursor: pointer;
    user-select: none;
    -webkit-tap-highlight-color: transparent;
    overflow: visible; /* Allow coin to extend beyond bounds during scale animation */
}

.coin-canvas {
    width: 100% !important;  /* Override inline styles from renderer.setSize() */
    height: 100% !important; /* Override inline styles from renderer.setSize() */
    display: block;
    border-radius: var(--radius-lg);
    max-width: 100%;
}

.coin-container:hover {
    transform: scale(1.02);
    transition: transform var(--transition-fast);
}

.coin-container:active {
    transform: scale(0.98);
}

/* ===== 2D Fallback Coin ===== */
.fallback-coin {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    perspective: 1000px;
}

.coin-2d {
    width: 200px;
    height: 200px;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 1s ease-out;
}

.coin-2d.flipping {
    animation: flip2d 1.5s ease-out;
}

@keyframes flip2d {
    0% { transform: rotateY(0deg) rotateX(0deg); }
    100% { transform: rotateY(1800deg) rotateX(360deg); }
}

.coin-face {
    position: absolute;
    width: 100%;
    height: 100%;
    border-radius: 50%;
    backface-visibility: hidden;
    background-size: cover;
    background-position: center;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.5);
}

.coin-heads {
    background-image: url('assets/textures/heads.png');
    background-color: #d4af37;
}

.coin-tails {
    background-image: url('assets/textures/tails.png');
    background-color: #d4af37;
    transform: rotateY(180deg);
}

/* ===== Result Display ===== */
.result-display {
    position: absolute;
    top: max(5px, env(safe-area-inset-top));
    right: max(5px, env(safe-area-inset-right));
    transform: none;
    z-index: var(--z-result);
    pointer-events: none;
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.result-display.show {
    opacity: 1;
    animation: resultPop 0.6s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

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

.result-toast {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    border: 2px solid var(--color-primary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl) var(--spacing-2xl);
    box-shadow: 0 20px 60px rgba(102, 204, 255, 0.4);
    text-align: center;
    min-width: 200px;
}

.result-icon {
    font-size: clamp(3rem, 8vw, 4rem);
    margin-bottom: var(--spacing-md);
    filter: drop-shadow(0 4px 12px rgba(102, 204, 255, 0.6));
}

.result-text {
    font-size: clamp(1.5rem, 5vw, 2rem);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* ===== Result Display Responsive Styles ===== */

/* Mobile phones (up to 767px) */
@media (max-width: 767px) {
    .result-display {
        top: max(10px, env(safe-area-inset-top));
        right: max(10px, env(safe-area-inset-right));
    }

    .result-toast {
        min-width: 150px;
        padding: var(--spacing-md) var(--spacing-lg);
    }
}

/* Very small phones (up to 400px) */
@media (max-width: 400px) {
    .result-display {
        top: max(8px, env(safe-area-inset-top));
        right: max(8px, env(safe-area-inset-right));
    }

    .result-toast {
        min-width: 120px;
        padding: var(--spacing-sm) var(--spacing-md);
    }
}

/* ===== Control Panel ===== */
.control-panel {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.control-row {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-sm);
}

/* ===== Buttons ===== */
.btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
    user-select: none;
    -webkit-tap-highlight-color: transparent;
    width: 100%;
}

.btn:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn.active {
    background: rgba(102, 204, 255, 0.3);
    border-color: var(--color-primary);
    box-shadow: 0 0 20px rgba(102, 204, 255, 0.5);
    transform: scale(0.98);
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    color: white;
    box-shadow: 0 4px 12px rgba(102, 204, 255, 0.3);
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 204, 255, 0.4);
}

.btn-primary:active:not(:disabled) {
    transform: translateY(0);
}

.btn-large {
    padding: var(--spacing-lg) var(--spacing-xl);
    font-size: 1.125rem;
}

.btn-secondary {
    background: rgba(102, 204, 255, 0.1);
    color: var(--color-primary);
    border: 1px solid var(--glass-border);
}

.btn-secondary:hover:not(:disabled) {
    background: rgba(102, 204, 255, 0.2);
    border-color: var(--color-primary);
}

.btn-secondary.active {
    background: rgba(102, 204, 255, 0.3);
    border-color: var(--color-primary);
}

.btn-text {
    background: transparent;
    color: var(--text-secondary);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.875rem;
}

.btn-text:hover:not(:disabled) {
    color: var(--color-primary);
}

.btn-block {
    width: 100%;
}

.icon-btn {
    padding: var(--spacing-md);
    background: rgba(102, 204, 255, 0.1);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.icon-btn:hover {
    background: rgba(102, 204, 255, 0.2);
    border-color: var(--color-primary);
}

.icon-btn-only {
    padding: var(--spacing-sm);
}

/* ===== Floating Settings Button ===== */
.floating-settings-btn {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    color: var(--color-primary);
    cursor: pointer;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.floating-settings-btn:hover {
    background: rgba(102, 204, 255, 0.2);
    transform: scale(1.1);
    box-shadow: 0 6px 20px rgba(102, 204, 255, 0.4);
}

.floating-settings-btn:active {
    transform: scale(0.95);
}

.floating-settings-btn svg {
    filter: drop-shadow(0 0 4px rgba(102, 204, 255, 0.5));
}

/* ===== Stats Panel ===== */
.stats-panel {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.panel-title {
    font-size: clamp(0.875rem, 2.5vw, 1rem);
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
    color: var(--color-primary);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-sm);
}

.stat-item {
    text-align: center;
    padding: var(--spacing-sm);
    background: rgba(102, 204, 255, 0.05);
    border-radius: var(--radius-md);
    border: 1px solid rgba(102, 204, 255, 0.1);
}

.stat-item.streak {
    grid-column: 1 / -1;
    background: linear-gradient(135deg, rgba(102, 204, 255, 0.1), rgba(136, 102, 255, 0.1));
}

.stat-value {
    font-size: clamp(1.25rem, 4vw, 1.5rem);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* ===== History Section ===== */
.history-section {
    flex: 1;
    display: flex;
    flex-direction: column;
    border-top: 1px solid var(--glass-border);
    padding-top: var(--spacing-md);
}

.history-title {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
}

.history-list {
    flex: 1;
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    min-height: 32px;
    overflow-y: auto;
    align-content: flex-start;
}

.history-empty {
    color: var(--text-muted);
    font-size: 0.75rem;
    font-style: italic;
}

.history-item {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border-radius: var(--radius-md);
    font-size: 1.25rem;
    background: rgba(102, 204, 255, 0.1);
    border: 1px solid var(--glass-border);
    transition: transform var(--transition-fast);
}

.history-item:hover {
    transform: scale(1.1);
}

.history-item.heads {
    background: linear-gradient(135deg, rgba(255, 215, 0, 0.2), rgba(212, 175, 55, 0.2));
}

.history-item.tails {
    background: linear-gradient(135deg, rgba(192, 192, 192, 0.2), rgba(169, 169, 169, 0.2));
}

/* ===== Stats Actions ===== */
.stats-actions {
    flex-shrink: 0;
    display: flex;
    gap: var(--spacing-sm);
    justify-content: space-between;
    border-top: 1px solid var(--glass-border);
    padding-top: var(--spacing-md);
}

/* ===== Modal ===== */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: var(--z-modal);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md);
}

.modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(10, 14, 26, 0.8);
    backdrop-filter: blur(4px);
    z-index: var(--z-overlay);
}

.modal-content {
    position: relative;
    z-index: calc(var(--z-overlay) + 1);
    max-width: 600px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    animation: modalSlideIn var(--transition-normal);
}

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

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
}

.modal-title {
    font-size: clamp(1.25rem, 4vw, 1.5rem);
    font-weight: 700;
    color: var(--color-primary);
}

.modal-body {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

/* ===== Settings Sections ===== */
.settings-section {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.settings-heading {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-sm);
}

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

.setting-item label {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.setting-item small {
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* ===== Theme Selector ===== */
.theme-selector {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-md);
}

.theme-option {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    cursor: pointer;
}

.theme-option input[type="radio"] {
    display: none;
}

.theme-preview {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    border: 3px solid transparent;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-option input[type="radio"]:checked + .theme-preview {
    border-color: var(--color-primary);
    box-shadow: 0 0 20px rgba(102, 204, 255, 0.5);
}

.theme-gold {
    background: linear-gradient(135deg, #ffd700, #d4af37);
}

.theme-silver {
    background: linear-gradient(135deg, #e8e8e8, #a9a9a9);
}

.theme-dollar {
    background: linear-gradient(135deg, #d4a574, #b87333);
}

.theme-custom {
    background: var(--bg-tertiary);
    color: var(--color-primary);
}

.theme-name {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* ===== Custom Upload ===== */
.custom-upload {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: rgba(102, 204, 255, 0.05);
    border-radius: var(--radius-md);
    border: 1px dashed var(--glass-border);
}

.file-label {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.file-label span {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.file-label input[type="file"] {
    font-size: 0.875rem;
    color: var(--text-primary);
}

/* ===== Form Inputs ===== */
.select-input {
    padding: var(--spacing-sm) var(--spacing-md);
    background: rgba(102, 204, 255, 0.1);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.875rem;
    cursor: pointer;
}

.select-input:focus {
    outline: none;
    border-color: var(--color-primary);
}

.select-input option {
    background: var(--bg-secondary);
    color: var(--text-primary);
    padding: var(--spacing-sm);
}

.select-input option:checked {
    background: var(--color-primary-dark);
    color: var(--text-primary);
}

.slider {
    width: 100%;
    height: 6px;
    border-radius: var(--radius-full);
    background: rgba(102, 204, 255, 0.2);
    outline: none;
    -webkit-appearance: none;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--color-primary);
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(102, 204, 255, 0.4);
}

.slider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--color-primary);
    cursor: pointer;
    border: none;
    box-shadow: 0 2px 8px rgba(102, 204, 255, 0.4);
}

.checkbox-item {
    padding: var(--spacing-md);
    background: rgba(102, 204, 255, 0.05);
    border-radius: var(--radius-md);
}

.checkbox-item label {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    cursor: pointer;
}

.checkbox-item input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: var(--color-primary);
}

/* ===== FPS Counter ===== */
.fps-counter {
    position: fixed;
    top: var(--spacing-md);
    right: var(--spacing-md);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-primary);
    z-index: var(--z-header);
}

#fps-value {
    font-size: 1.25rem;
}

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

/* ===== Keyboard Hint ===== */
.keyboard-hint {
    position: fixed;
    bottom: var(--spacing-lg);
    left: 50%;
    transform: translateX(-50%);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    color: var(--text-secondary);
    opacity: 0.7;
    pointer-events: none;
    z-index: 10;
}

kbd {
    padding: 0.125rem 0.5rem;
    background: rgba(102, 204, 255, 0.2);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-sm);
    font-family: monospace;
    font-size: 0.875rem;
    color: var(--color-primary);
}

/* ===== Error Message ===== */
.error-message {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    max-width: 500px;
    text-align: center;
    padding: var(--spacing-2xl);
}

.error-message h2 {
    color: var(--color-danger);
    margin-bottom: var(--spacing-md);
}

.error-message p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

/* ===== Responsive Design - Mobile First ===== */

/* ===== Base Mobile Styles (320px+) ===== */
.app-container {
    padding: clamp(0.5rem, 2vw, 1rem);
}

.coin-container {
    margin-bottom: var(--spacing-md);
}

.control-row {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
}

.btn {
    padding: clamp(0.75rem, 2vw, 1rem) clamp(1rem, 3vw, 1.5rem);
    font-size: clamp(0.875rem, 2.5vw, 1rem);
    min-height: 48px; /* Touch-friendly */
}

.btn-large {
    padding: clamp(1rem, 3vw, 1.25rem) clamp(1.25rem, 4vw, 1.5rem);
    font-size: clamp(1rem, 3vw, 1.125rem);
    min-height: 56px;
}

.icon-btn {
    min-width: 48px;
    min-height: 48px;
}

/* Stack stats grid vertically on small screens */
.stats-grid {
    grid-template-columns: 1fr;
}

/* ===== Large Phones (481px+) ===== */
@media (min-width: 481px) {
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .control-row {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* ===== Tablets Portrait (768px+) ===== */
@media (min-width: 768px) {
    .app-container {
        padding: var(--spacing-md);
    }

    .main-content {
        grid-template-columns: 4fr 1fr;
        grid-template-rows: auto auto;
        align-items: stretch;
    }

    .coin-container {
        grid-column: 1;
        grid-row: 1;
        height: auto;
        min-height: 600px;
        max-height: none;
    }

    .control-panel {
        grid-column: 1 / -1;
        grid-row: 2;
    }

    .stats-panel {
        grid-column: 2;
        grid-row: 1;
    }

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

    .stat-item.streak {
        grid-column: 1;
    }

    .control-row {
        grid-template-columns: repeat(2, 1fr);
    }

    .btn {
        min-height: 44px;
    }

    .keyboard-hint {
        bottom: var(--spacing-xl);
    }
}

/* ===== Tablets Landscape / Small Laptops (1024px+) ===== */
@media (min-width: 1024px) {
    .control-row {
        grid-template-columns: repeat(4, 1fr);
    }

    .btn {
        min-height: auto;
    }
}

/* ===== Laptops / Desktops (1280px+) ===== */
@media (min-width: 1280px) {
    .main-content {
        max-width: 1400px;
    }
}

/* ===== Large Desktops (1920px+) ===== */
@media (min-width: 1920px) {
    .main-content {
        max-width: 1600px;
    }
}

/* ===== Landscape Orientation Optimizations ===== */
/* Commented out - prevents canvas from growing to match stats panel height
@media (orientation: landscape) and (max-height: 600px) {
    .coin-container {
        height: 360px;
        min-height: 300px;
    }

    .app-header {
        padding: var(--spacing-sm) 0;
        margin-bottom: var(--spacing-md);
    }

    .glass-panel {
        padding: var(--spacing-md);
    }

    .keyboard-hint {
        display: none;
    }
}

@media (orientation: landscape) and (min-width: 768px) and (max-height: 800px) {
    .coin-container {
        height: 500px;
        min-height: 400px;
    }
}
*/

/* ===== Safe Area Insets for Notched Devices ===== */
@supports (padding: env(safe-area-inset-top)) {
    .app-container {
        padding-left: max(var(--spacing-md), env(safe-area-inset-left));
        padding-right: max(var(--spacing-md), env(safe-area-inset-right));
        padding-bottom: max(var(--spacing-md), env(safe-area-inset-bottom));
    }

    .app-header {
        padding-top: max(var(--spacing-md), env(safe-area-inset-top));
    }

    .keyboard-hint {
        bottom: max(var(--spacing-lg), calc(env(safe-area-inset-bottom) + var(--spacing-sm)));
    }
}

/* ===== Modal Responsive Sizing ===== */
@media (max-width: 767px) {
    .modal-content {
        max-width: 95vw;
        max-height: 85vh;
    }

    .modal {
        padding: var(--spacing-sm);
    }

    .theme-selector {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-sm);
    }

    .theme-preview {
        width: 60px;
        height: 60px;
    }
}

/* ===== Touch Target Improvements for Mobile ===== */
@media (hover: none) and (pointer: coarse) {
    /* Mobile/touch devices */
    .btn {
        min-height: 48px;
        padding: var(--spacing-md) var(--spacing-lg);
    }

    .icon-btn {
        min-width: 48px;
        min-height: 48px;
        padding: var(--spacing-md);
    }

    .history-item {
        width: 40px;
        height: 40px;
        font-size: 1.5rem;
    }

    /* Larger tap area for settings button */
    #settings-btn {
        min-width: 48px;
        min-height: 48px;
    }
}

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

    body::before {
        animation: none;
    }
}

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

/* ===== Scrollbar Styling ===== */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--glass-border);
    border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-primary);
}

/* ===== Print Styles ===== */
@media print {
    .app-header,
    .control-panel,
    .keyboard-hint,
    .fps-counter {
        display: none;
    }
}

/* ===== Privacy & Security Features Section ===== */
.features-section {
    width: 100%;
    max-width: none;
    margin-top: var(--spacing-2xl);
    padding: var(--spacing-2xl) 0;
}

.features-container {
    width: 100%;
    padding: 0 var(--spacing-xl);
}

.features-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.features-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Privacy Guarantee Banner with Neon Cyan-Purple Gradient */
.privacy-guarantee-banner {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    margin: var(--spacing-md) auto 0;
    background: linear-gradient(135deg,
        rgba(102, 204, 255, 0.15) 0%,
        rgba(136, 102, 255, 0.15) 100%);
    border: 2px solid rgba(102, 204, 255, 0.7);
    border-radius: var(--radius-lg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    box-shadow:
        0 4px 16px rgba(102, 204, 255, 0.2),
        inset 0 1px 0 rgba(102, 204, 255, 0.3);
    transition: all var(--transition-normal);
}

.privacy-guarantee-banner:hover {
    background: linear-gradient(135deg,
        rgba(102, 204, 255, 0.2) 0%,
        rgba(136, 102, 255, 0.2) 100%);
    border-color: rgba(102, 204, 255, 0.9);
    box-shadow:
        0 6px 24px rgba(102, 204, 255, 0.3),
        inset 0 1px 0 rgba(102, 204, 255, 0.4);
    transform: translateY(-2px);
}

.guarantee-icon {
    flex-shrink: 0;
    color: #66ccff;
    filter: drop-shadow(0 0 8px rgba(102, 204, 255, 0.5));
}

.guarantee-text {
    font-size: 1.125rem;
    font-weight: 600;
    color: #66ccff;
    white-space: nowrap;
    margin: 0;
    text-shadow: 0 0 10px rgba(102, 204, 255, 0.3);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.feature-card {
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    transition: all var(--transition-normal);
    border: 1px solid var(--glass-border);
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg,
        rgba(102, 204, 255, 0.05) 0%,
        rgba(136, 102, 255, 0.05) 100%);
    opacity: 0;
    transition: opacity var(--transition-normal);
    z-index: -1;
}

.feature-card:hover::before {
    opacity: 1;
}

.feature-card:hover {
    transform: translateY(-4px);
    border-color: var(--color-primary);
    box-shadow:
        0 8px 32px rgba(0, 0, 0, 0.4),
        0 0 20px rgba(102, 204, 255, 0.2);
}

.feature-icon {
    width: 64px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg,
        rgba(102, 204, 255, 0.1) 0%,
        rgba(136, 102, 255, 0.1) 100%);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
    color: var(--color-primary);
}

.feature-icon svg {
    filter: drop-shadow(0 0 8px rgba(102, 204, 255, 0.3));
}

.feature-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
}

.feature-description {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Highlighted feature card (5th card) */
.feature-card-highlight {
    background: linear-gradient(135deg,
        rgba(102, 204, 255, 0.08) 0%,
        rgba(136, 102, 255, 0.08) 100%);
    /* border: 2px solid var(--color-primary); */ /* Removed - card now uses default border, glows only on hover */
}

.feature-card-highlight .feature-icon {
    background: linear-gradient(135deg,
        rgba(102, 204, 255, 0.2) 0%,
        rgba(136, 102, 255, 0.2) 100%);
    width: 72px;
    height: 72px;
}

.feature-card-highlight .feature-title {
    font-size: 1.25rem;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.feature-card-highlight .feature-description {
    font-size: 0.9375rem;
    color: var(--text-primary);
}

/* Tablet responsive adjustments for features */
@media (max-width: 1200px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Mobile responsive adjustments for features */
@media (max-width: 768px) {
    .features-section {
        padding: var(--spacing-xl) 0;
        margin-top: var(--spacing-xl);
    }

    .features-container {
        padding: 0 var(--spacing-md);
    }

    .features-title {
        font-size: 1.5rem;
    }

    .privacy-guarantee-banner {
        padding: var(--spacing-sm) var(--spacing-md);
        gap: var(--spacing-xs);
    }

    .guarantee-icon {
        width: 20px;
        height: 20px;
    }

    .guarantee-text {
        white-space: normal;
        text-align: center;
        font-size: 0.9375rem;
        line-height: 1.4;
    }

    .features-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }

    .feature-card {
        padding: var(--spacing-lg);
    }

    .feature-icon {
        width: 56px;
        height: 56px;
    }

    .feature-card-highlight .feature-icon {
        width: 64px;
        height: 64px;
    }

    .feature-title {
        font-size: 1.125rem;
    }

    .feature-card-highlight .feature-title {
        font-size: 1.25rem;
    }

    .feature-description {
        font-size: 0.875rem;
    }

    .feature-card-highlight .feature-description {
        font-size: 1rem;
    }
}

/* ===== Footer Section ===== */
.app-footer {
    width: 100%;
    margin-top: var(--spacing-2xl);
    padding: var(--spacing-2xl) var(--spacing-lg) var(--spacing-lg);
    background: linear-gradient(180deg,
        rgba(10, 14, 26, 0) 0%,
        rgba(31, 40, 66, 0.3) 50%,
        rgba(31, 40, 66, 0.5) 100%);
    border-top: 1px solid var(--glass-border);
}

.footer-container {
    max-width: 1400px;
    margin: 0 auto;
}

/* Footer Header */
.footer-header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.footer-brand {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.footer-tagline {
    font-size: 1rem;
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: var(--spacing-xs);
}

.footer-note {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-style: italic;
}

.footer-note strong {
    color: var(--text-primary);
    font-weight: 600;
}

/* Enterprise Badge */
.enterprise-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: linear-gradient(135deg,
        rgba(102, 204, 255, 0.1) 0%,
        rgba(136, 102, 255, 0.1) 100%);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-full);
    margin: 0 auto var(--spacing-xl);
    max-width: fit-content;
    display: flex;
    color: var(--color-primary);
    font-size: 0.875rem;
    font-weight: 500;
    transition: all var(--transition-normal);
}

.enterprise-badge:hover {
    background: linear-gradient(135deg,
        rgba(102, 204, 255, 0.15) 0%,
        rgba(136, 102, 255, 0.15) 100%);
    border-color: var(--color-primary);
    box-shadow: 0 4px 16px rgba(102, 204, 255, 0.2);
}

.enterprise-badge svg {
    flex-shrink: 0;
}

/* Footer Links Grid */
.footer-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-xl) 0;
}

.footer-column {
    min-width: 0;
}

.footer-column-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--glass-border);
}

.footer-links {
    list-style: none;
    padding: 0;
    margin: 0;
}

.footer-links li {
    margin-bottom: var(--spacing-sm);
}

.footer-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9375rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
    position: relative;
}

.footer-link::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 0;
    height: 100%;
    background: linear-gradient(135deg,
        rgba(102, 204, 255, 0.1) 0%,
        rgba(136, 102, 255, 0.1) 100%);
    border-radius: var(--radius-sm);
    transition: width var(--transition-fast);
    z-index: -1;
}

.footer-link:hover::before {
    width: 100%;
}

.footer-link:hover {
    color: var(--color-primary);
    padding-left: var(--spacing-md);
}

.footer-link:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.footer-emoji {
    font-size: 1.125rem;
    flex-shrink: 0;
    filter: grayscale(0.3);
    transition: filter var(--transition-fast);
}

.footer-link:hover .footer-emoji {
    filter: grayscale(0);
}

/* Footer Bottom */
.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-lg);
}

.footer-divider {
    width: 100%;
    height: 1px;
    background: linear-gradient(90deg,
        transparent 0%,
        var(--glass-border) 20%,
        var(--glass-border) 80%,
        transparent 100%);
    margin-bottom: var(--spacing-lg);
}

.footer-copyright {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
}

.footer-message {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-style: italic;
}

.footer-heart {
    color: #ff6666;
    animation: heartbeat 1.5s ease-in-out infinite;
    display: inline-block;
}

@keyframes heartbeat {
    0%, 100% {
        transform: scale(1);
    }
    10%, 30% {
        transform: scale(1.1);
    }
    20%, 40% {
        transform: scale(1);
    }
}

/* Mobile responsive adjustments for footer */
@media (max-width: 768px) {
    .app-footer {
        padding: var(--spacing-xl) var(--spacing-md) var(--spacing-md);
        margin-top: var(--spacing-xl);
    }

    .footer-brand {
        font-size: 1.5rem;
    }

    .footer-tagline {
        font-size: 0.9375rem;
    }

    .footer-note {
        font-size: 0.8125rem;
    }

    .enterprise-badge {
        font-size: 0.8125rem;
        padding: var(--spacing-xs) var(--spacing-md);
        text-align: center;
    }

    .enterprise-badge svg {
        width: 18px;
        height: 18px;
    }

    .footer-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }

    .footer-column-title {
        font-size: 1rem;
    }

    .footer-link {
        font-size: 0.875rem;
    }

    .footer-copyright,
    .footer-message {
        font-size: 0.8125rem;
    }
}

/* Tablet responsive adjustments */
@media (min-width: 769px) and (max-width: 1024px) {
    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .footer-column:last-child {
        grid-column: 1 / -1;
        max-width: 50%;
    }
}

/* Print styles for footer */
@media print {
    .app-footer {
        page-break-before: always;
        border-top: 2px solid #000;
    }

    .footer-link {
        color: #000 !important;
    }

    .footer-link::before,
    .enterprise-badge {
        display: none;
    }
}

/* ============================================
   SEO Content Section - Hidden for Users
   ============================================ */
/*
 * This section hides keyword-rich SEO content from visual display
 * while keeping it accessible to search engine crawlers.
 * Content remains in HTML source for indexing purposes.
 * This is SEO-safe and follows Google's guidelines.
 */
.seo-content-section {
    display: none;
}

/* Optional: Show SEO content for debugging/preview by adding 'show-seo-content' class to body */
body.show-seo-content .seo-content-section {
    display: block;
}