/* ==========================================================================
   Design System & Tokens
   ========================================================================== */
:root {
    --primary-color: #40B29A;
    /* Custom Teal */
    --primary-hover: #338F7A;
    /* Darker Teal */
    --bg-color: #F8FAFC;
    /* Slate 50 */
    --card-bg: #FFFFFF;
    --text-main: #1E293B;
    /* Slate 800 */
    --text-muted: #64748B;
    --border-color: #E2E8F0;
    --error-color: #EF4444;
    --success-color: #40B29A;
    --hint-color: #40B29A;

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);

    --border-radius-sm: 8px;
    --border-radius-md: 12px;
    --border-radius-lg: 16px;
    --border-radius-full: 9999px;
}

/* ==========================================================================
   Reset & Base Styles
   ========================================================================== */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
    /* Remove tap highlight on iOS */
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
    /* Prevent overscroll bounce on body */
    overscroll-behavior-y: none;
}



rt {
    font-size: 0.6em;
    text-align: center;
    line-height: 1;
}

button {
    font-family: inherit;
    border: none;
    cursor: pointer;
    background: none;
}

/* ==========================================================================
   Layout Containers
   ========================================================================== */
.app-container {
    max-width: 1024px;
    margin: 0 auto;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
}

.screen {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding: 16px 24px;
    transition: opacity 0.3s ease, transform 0.3s ease;
    opacity: 0;
    pointer-events: none;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
}

.screen.active {
    opacity: 1;
    pointer-events: auto;
    z-index: 10;
    position: relative;
}

.hidden {
    display: none !important;
}

.mt-large {
    margin-top: 32px;
}

/* ==========================================================================
   Start Screen UI
   ========================================================================== */
#start-screen {
    justify-content: center;
    align-items: center;
    text-align: center;
}

#start-screen h1 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 2rem;
    color: var(--primary-color);
    text-shadow: 0 2px 4px rgba(64, 178, 154, 0.1);
}

.settings-group {
    background: var(--card-bg);
    padding: 24px;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    margin-bottom: 1.5rem;
    width: 100%;
    max-width: 500px;
}

.settings-group h3 {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    color: var(--text-main);
}

.help-text {
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-top: 0.75rem;
}

/* ==========================================================================
   Google Auth & Settings
   ========================================================================== */
.auth-section {
    background: #f9fafb;
    border: 1px solid var(--border-color);
    padding: 12px 15px;
    border-radius: var(--border-radius-md);
    margin-bottom: 24px;
    width: 100%;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.auth-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
}

.auth-body {
    margin-top: 15px;
    border-top: 1px solid var(--border-color);
    padding-top: 24px;
    text-align: left;
}

.auth-body label {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-main);
    display: block;
    margin-bottom: 8px;
}

.toggle-icon {
    font-size: 12px;
    color: var(--text-muted);
    transition: transform 0.3s;
}

.expanded .toggle-icon {
    transform: rotate(180deg);
}

.auth-row {
    display: flex;
    align-items: center;
    gap: 12px;
}

.outline-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    padding: 8px 16px;
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: all 0.2s;
    font-weight: 600;
    color: var(--text-main);
}

.outline-btn:hover {
    background: #f1f5f9;
}

.spreadsheet-id-input {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    font-size: 1rem;
}

/* Segmented Controls / Selectors */
.mode-selector,
.time-selector {
    display: flex;
    background: var(--bg-color);
    padding: 6px;
    border-radius: var(--border-radius-full);
    border: 1px solid var(--border-color);
}

.header-left {
    display: flex;
    align-items: center;
    gap: 12px;
}

.header-right {
    display: flex;
    align-items: center;
    justify-content: center;
}

.size-selector {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    justify-content: center;
}

.mode-btn,
.time-btn {
    flex: 1;
    padding: 12px 16px;
    border-radius: var(--border-radius-full);
    font-weight: 600;
    color: var(--text-muted);
    transition: all 0.2s;
    font-size: 1rem;
}

.size-btn {
    padding: 10px 16px;
    border-radius: var(--border-radius-md);
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    font-weight: 600;
    color: var(--text-muted);
    transition: all 0.2s;
    font-size: 1rem;
}

.mode-btn.active,
.time-btn.active,
.size-btn.active {
    background: var(--card-bg);
    color: var(--primary-color);
    box-shadow: var(--shadow-sm);
}

.size-btn.active {
    border-color: var(--primary-color);
    background: rgba(64, 178, 154, 0.05);
    /* Match theme color */
}

/* Slider Custom Styles */
.slider-container {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-top: 8px;
}

.range-slider {
    flex: 1;
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 8px;
    border-radius: 4px;
    background: var(--bg-color);
    outline: none;
    border: 1px solid var(--border-color);
}

.range-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    transition: transform 0.1s;
}

.range-slider::-webkit-slider-thumb:active {
    transform: scale(1.1);
}

.slider-value {
    font-weight: 600;
    color: var(--primary-color);
    min-width: 3rem;
    text-align: right;
}

/* Buttons */
.primary-btn {
    background-color: var(--primary-color);
    color: white;
    font-size: 1.25rem;
    font-weight: 600;
    padding: 16px 32px;
    border-radius: var(--border-radius-full);
    box-shadow: var(--shadow-md);
    transition: transform 0.1s, background-color 0.2s, box-shadow 0.2s;
    width: 100%;
    max-width: 300px;
}

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

.primary-btn:hover {
    background-color: var(--primary-hover);
    box-shadow: var(--shadow-lg);
}

.secondary-btn {
    background-color: var(--card-bg);
    color: var(--text-main);
    border: 1px solid var(--border-color);
    font-size: 1.1rem;
    font-weight: 600;
    padding: 12px 24px;
    border-radius: var(--border-radius-full);
    box-shadow: var(--shadow-sm);
    transition: all 0.2s;
}

.secondary-btn:active {
    background-color: var(--bg-color);
}

/* ==========================================================================
   Game Screen UI
   ========================================================================== */
.game-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: 12px;
}

.icon-btn {
    font-size: 1.25rem;
    padding: 8px 16px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--border-radius-full);
    background: var(--card-bg);
    box-shadow: var(--shadow-sm);
    color: var(--text-main);
    font-weight: 600;
}

.level-badge,
.timer-badge,
#timer-display {
    background: var(--card-bg);
    padding: 8px 16px;
    height: 44px;
    display: flex;
    align-items: baseline;
    border-radius: var(--border-radius-full);
    box-shadow: var(--shadow-sm);
    font-weight: bold;
    color: var(--text-main);
}

.timer-badge {
    color: var(--primary-color);
}

/* Grid Layout */
.game-board-container {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100%;
}

.grid {
    display: grid;
    gap: 8px;
    width: min(100%, 60vh);
    max-width: 600px;
    aspect-ratio: 1 / 1;
}

/* Cards */
.card {
    background: var(--card-bg);
    border-radius: var(--border-radius-md);
    box-shadow: var(--shadow-sm);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2.5rem;
    /* Dynamic based on grid size later */
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s, background-color 0.3s;
    user-select: none;
    border: 2px solid transparent;
}

.card:active {
    transform: scale(0.95);
}

.card.blank {
    background: #E2E8F0;
    cursor: pointer;
}

.card.blank:hover {
    background: #CBD5E1;
}

/* Add some subtle styling for correct/wrong state if we need it */
.card.correct-anim {
    animation: pop 0.3s ease;
    border-color: var(--success-color);
}

@keyframes pop {
    0% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.1);
    }

    100% {
        transform: scale(1);
    }
}

/* Game Footer */
.game-footer {
    padding-top: 12px;
    text-align: center;
}

.feedback-area {
    min-height: 32px;
    margin-bottom: 12px;
}

.result-message {
    font-size: 1.25rem;
    font-weight: 600;
}

.result-message.error {
    color: var(--error-color);
    animation: shake 0.4s ease;
}

.result-message.success {
    color: var(--success-color);
}

@keyframes shake {

    0%,
    100% {
        transform: translateX(0);
    }

    25% {
        transform: translateX(-5px);
    }

    75% {
        transform: translateX(5px);
    }
}

.action-area {
    display: flex;
    justify-content: center;
    gap: 16px;
}

/* ==========================================================================
   Popup Palette (Modal)
   ========================================================================== */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(15, 23, 42, 0.5);
    /* Slate 900 */
    backdrop-filter: blur(4px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 100;
    opacity: 0;
    transition: opacity 0.2s;
    pointer-events: none;
}

.overlay:not(.hidden) {
    opacity: 1;
    pointer-events: auto;
}

.palette-modal {
    background: var(--card-bg);
    border-radius: var(--border-radius-lg);
    padding: 24px;
    width: 90%;
    max-width: 450px;
    box-shadow: var(--shadow-lg);
    transform: translateY(20px);
    transition: transform 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.overlay:not(.hidden) .palette-modal {
    transform: translateY(0);
}

.palette-modal h3 {
    text-align: center;
    margin-bottom: 20px;
    color: var(--text-main);
}

.palette-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 12px;
    margin-bottom: 24px;
}

.palette-item {
    aspect-ratio: 1/1;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2rem;
    background: var(--bg-color);
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: background 0.2s, transform 0.1s;
    border: 1px solid var(--border-color);
}

.palette-item:active {
    transform: scale(0.9);
    background: #E2E8F0;
}

.close-btn {
    width: 100%;
    padding: 12px;
    background: var(--bg-color);
    color: var(--text-main);
    font-weight: 600;
    border-radius: var(--border-radius-md);
    border: 1px solid var(--border-color);
}

/* ==========================================================================
   Auth Section (Google Integration)
   ========================================================================== */
.auth-section {
    background: var(--card-bg);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    margin-bottom: 24px;
    width: 100%;
    max-width: 500px;
    overflow: hidden;
    transition: all 0.3s ease;
}

.auth-header {
    padding: 16px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    background: #f8fafc;
    border-bottom: 1px solid transparent;
    transition: background 0.2s;
}

.auth-header:hover {
    background: #f1f5f9;
}

.auth-header.open {
    border-bottom-color: var(--border-color);
}

.auth-body {
    padding: 20px;
    background: var(--card-bg);
    animation: slideDown 0.3s ease-out forwards;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.auth-row {
    display: flex;
    align-items: center;
    gap: 12px;
}

.outline-btn {
    padding: 8px 16px;
    border: 1px solid var(--border-color);
    background: white;
    border-radius: var(--border-radius-sm);
    font-weight: 600;
    color: var(--text-main);
    transition: all 0.2s;
}

.outline-btn:hover {
    background: #f8fafc;
    border-color: #cbd5e1;
}

.spreadsheet-id-input {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    font-size: 14px;
    margin-top: 8px;
    transition: border-color 0.2s;
}

.spreadsheet-id-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(64, 178, 154, 0.1);
}

.toggle-icon {
    transition: transform 0.3s ease;
    color: var(--text-muted);
}

.auth-header.open .toggle-icon {
    transform: rotate(180deg);
}