/* ===== CSS Variables & Reset ===== */
:root {
    /* Theme Colors - matching Swift app */
    --theme-pink: #FFD9EC;
    --theme-dark-pink: #F599C2;
    --theme-purple: #BAA6E6;
    --theme-text: #663366;
    --theme-white: #FFFFFF;
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #FFD9EC 0%, #F599C2 100%);
    --gradient-secondary: linear-gradient(135deg, #BAA6E6 0%, #F599C2 100%);
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.15);
    --shadow-colored: 0 4px 12px rgba(245, 153, 194, 0.3);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 25px;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    background: var(--theme-pink);
    color: var(--theme-text);
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    min-height: 100vh;
}

/* ===== Decorative Background ===== */
.decorative-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--theme-pink);
    z-index: -1;
    overflow: hidden;
}

.decorative-background::before,
.decorative-background::after {
    content: '';
    position: absolute;
    border-radius: 50%;
    opacity: 0.15;
    animation: float 20s infinite ease-in-out;
}

.decorative-background::before {
    width: 300px;
    height: 300px;
    background: var(--theme-purple);
    top: -100px;
    right: -100px;
    animation-delay: 0s;
}

.decorative-background::after {
    width: 200px;
    height: 200px;
    background: var(--theme-dark-pink);
    bottom: -50px;
    left: -50px;
    animation-delay: 5s;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(20px, -20px) scale(1.1); }
    50% { transform: translate(-20px, 20px) scale(0.9); }
    75% { transform: translate(20px, 20px) scale(1.05); }
}

/* ===== Layout ===== */
.screen {
    display: none;
    min-height: 100vh;
    padding-bottom: 2rem;
}

.screen.active {
    display: block;
    animation: fadeIn 0.3s ease-in-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.container {
    max-width: 600px;
    margin: 0 auto;
    padding: var(--spacing-md);
}

/* ===== Header ===== */
.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
    animation: slideDown 0.5s ease-out;
}

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

.app-title {
    font-size: 2.5rem;
    font-weight: 900;
    color: var(--theme-text);
    text-align: center;
    flex: 1;
    letter-spacing: -0.5px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.05);
}

.settings-btn,
.back-btn {
    width: 40px;
    height: 40px;
    border: none;
    background: var(--theme-white);
    color: var(--theme-text);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}

.settings-btn:hover,
.back-btn:hover {
    transform: scale(1.1) rotate(90deg);
    box-shadow: var(--shadow-md);
}

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

.screen-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--theme-text);
}

/* ===== Settings Panel ===== */
.settings-panel {
    background: var(--theme-white);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-md);
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
    animation: scaleIn 0.4s ease-out 0.1s backwards;
}

@keyframes scaleIn {
    from { opacity: 0; transform: scale(0.9); }
    to { opacity: 1; transform: scale(1); }
}

.setting-group {
    flex: 1;
    min-width: 150px;
}

.setting-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--theme-text);
    margin-bottom: var(--spacing-xs);
}

.grade-select {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--theme-dark-pink);
    border-radius: var(--radius-sm);
    background: var(--theme-white);
    color: var(--theme-text);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    font-family: var(--font-family);
}

.grade-select:focus {
    outline: none;
    border-color: var(--theme-purple);
    box-shadow: 0 0 0 3px rgba(186, 166, 230, 0.2);
}

.provider-toggle {
    display: flex;
    gap: 0.5rem;
    background: #F5F5F5;
    padding: 4px;
    border-radius: var(--radius-sm);
}

.provider-btn {
    flex: 1;
    padding: 0.5rem 1rem;
    border: none;
    background: transparent;
    color: var(--theme-text);
    font-size: 0.875rem;
    font-weight: 600;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-family: var(--font-family);
}

.provider-btn.active {
    background: var(--theme-white);
    box-shadow: var(--shadow-sm);
}

.provider-btn:hover:not(.active) {
    background: rgba(255, 255, 255, 0.5);
}

/* ===== Image Upload Area ===== */
.image-upload-area {
    position: relative;
    background: var(--theme-white);
    border: 3px dashed var(--theme-dark-pink);
    border-radius: var(--radius-xl);
    height: 250px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-bottom: var(--spacing-md);
    overflow: hidden;
    animation: scaleIn 0.4s ease-out 0.2s backwards;
}

.image-upload-area:hover {
    border-color: var(--theme-purple);
    transform: scale(1.02);
    box-shadow: var(--shadow-colored);
}

.upload-placeholder {
    text-align: center;
    color: var(--theme-purple);
    transition: all 0.3s ease;
}

.upload-placeholder svg {
    margin-bottom: var(--spacing-sm);
    opacity: 0.8;
}

.upload-placeholder p {
    font-size: 1.125rem;
    font-weight: 600;
}

.image-upload-area:hover .upload-placeholder {
    transform: scale(1.05);
}

.preview-image {
    width: 100%;
    height: 100%;
    object-fit: contain;
    border-radius: var(--radius-md);
}

.remove-image-btn {
    position: absolute;
    top: 10px;
    right: 10px;
    width: 36px;
    height: 36px;
    border: none;
    background: rgba(255, 255, 255, 0.95);
    color: #E53E3E;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-md);
    z-index: 10;
}

.remove-image-btn:hover {
    transform: scale(1.1) rotate(90deg);
    background: #E53E3E;
    color: white;
}

/* ===== Prompt Section ===== */
.prompt-section {
    margin-bottom: var(--spacing-md);
    animation: slideUp 0.3s ease-out;
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.prompt-input {
    width: 100%;
    padding: 0.875rem 1rem;
    border: 2px solid #E2E8F0;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-family: var(--font-family);
    transition: all 0.3s ease;
}

.prompt-input:focus {
    outline: none;
    border-color: var(--theme-purple);
    box-shadow: 0 0 0 3px rgba(186, 166, 230, 0.2);
}

/* ===== Action Buttons ===== */
.action-buttons {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    animation: scaleIn 0.4s ease-out 0.3s backwards;
}

.btn {
    flex: 1;
    padding: 1rem 1.5rem;
    border: none;
    border-radius: var(--radius-xl);
    font-size: 1rem;
    font-weight: 700;
    font-family: var(--font-family);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-md);
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.btn:active::before {
    width: 300px;
    height: 300px;
}

.btn-camera {
    background: var(--theme-purple);
    color: white;
}

.btn-camera:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(186, 166, 230, 0.4);
}

.btn-solve {
    background: var(--theme-dark-pink);
    color: white;
}

.btn-solve:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(245, 153, 194, 0.4);
}

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

.btn:active:not(:disabled) {
    transform: translateY(0) scale(0.98);
}

/* Loading state */
.btn.loading {
    pointer-events: none;
}

.btn.loading::after {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

/* ===== Error Message ===== */
.error-message {
    background: #FEE;
    color: #C53030;
    padding: var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    text-align: center;
    margin-bottom: var(--spacing-md);
    animation: shake 0.5s ease-in-out;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-10px); }
    75% { transform: translateX(10px); }
}

/* ===== Footer ===== */
.footer {
    text-align: center;
    margin-top: var(--spacing-xl);
    animation: fadeIn 0.5s ease-out 0.4s backwards;
}

.footer p {
    font-size: 0.875rem;
    color: var(--theme-text);
    opacity: 0.6;
}

/* ===== Result Content ===== */
.result-content {
    margin-bottom: var(--spacing-lg);
    max-height: calc(100vh - 350px);
    overflow-y: auto;
    padding-right: 0.5rem;
}

.result-content::-webkit-scrollbar {
    width: 6px;
}

.result-content::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.3);
    border-radius: 3px;
}

.result-content::-webkit-scrollbar-thumb {
    background: var(--theme-purple);
    border-radius: 3px;
}

.math-problem,
.english-word {
    background: var(--theme-white);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
    box-shadow: var(--shadow-md);
    animation: slideUp 0.4s ease-out;
    border: 1px solid rgba(245, 153, 194, 0.3);
}

.math-problem h3,
.english-word h3 {
    color: var(--theme-text);
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.math-problem .question {
    font-size: 1rem;
    color: #2D3748;
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

.math-problem .steps {
    margin: var(--spacing-md) 0;
}

.math-problem .step {
    display: flex;
    gap: 0.75rem;
    margin-bottom: var(--spacing-sm);
    align-items: flex-start;
}

.math-problem .step-icon {
    color: var(--theme-dark-pink);
    flex-shrink: 0;
    margin-top: 2px;
}

.math-problem .step-text {
    color: #2D3748;
    line-height: 1.6;
}

.math-problem .answer {
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 2px solid #F7FAFC;
}

.math-problem .answer-label {
    font-weight: 700;
    color: var(--theme-text);
    margin-right: 0.5rem;
}

.math-problem .answer-value {
    font-weight: 700;
    color: var(--theme-purple);
    font-size: 1.125rem;
}

/* Geometry Canvas */
.geometry-canvas {
    width: 100%;
    height: 300px;
    background: #F7FAFC;
    border-radius: var(--radius-md);
    margin: var(--spacing-md) 0;
    border: 2px solid #E2E8F0;
}

/* English Word Card */
.english-word {
    border: 1px solid rgba(186, 166, 230, 0.3);
}

.word-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: var(--spacing-sm);
}

.word-info h3 {
    font-size: 1.5rem;
    color: var(--theme-purple);
    margin-bottom: 0.25rem;
}

.word-translation {
    font-size: 1.125rem;
    color: #718096;
    font-weight: 600;
}

.speak-btn {
    width: 48px;
    height: 48px;
    border: none;
    background: var(--gradient-secondary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
    flex-shrink: 0;
}

.speak-btn:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-colored);
}

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

.word-example {
    font-style: italic;
    color: #4A5568;
    line-height: 1.6;
    margin-top: var(--spacing-sm);
}

/* ===== Feedback Section ===== */
.feedback-section {
    background: var(--theme-white);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    animation: slideUp 0.4s ease-out 0.2s backwards;
}

.feedback-section h3 {
    color: var(--theme-text);
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.feedback-input {
    width: 100%;
    padding: 0.875rem 1rem;
    border: 2px solid #E2E8F0;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-family: var(--font-family);
    margin-bottom: var(--spacing-sm);
    transition: all 0.3s ease;
}

.feedback-input:focus {
    outline: none;
    border-color: var(--theme-purple);
    box-shadow: 0 0 0 3px rgba(186, 166, 230, 0.2);
}

.btn-feedback {
    width: 100%;
    background: var(--theme-dark-pink);
    color: white;
}

.btn-feedback:disabled {
    opacity: 0.5;
}

/* ===== Modal ===== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md);
}

.modal.active {
    display: flex;
    animation: fadeIn 0.3s ease-out;
}

.modal-content {
    background: var(--theme-white);
    border-radius: var(--radius-lg);
    width: 100%;
    max-width: 500px;
    box-shadow: var(--shadow-lg);
    animation: slideUp 0.3s ease-out;
    max-height: 90vh;
    overflow-y: auto;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
    border-bottom: 2px solid #F7FAFC;
}

.modal-header h3 {
    color: var(--theme-text);
    font-size: 1.25rem;
    font-weight: 700;
}

.close-btn {
    width: 32px;
    height: 32px;
    border: none;
    background: transparent;
    color: var(--theme-text);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: all 0.3s ease;
}

.close-btn:hover {
    background: #F7FAFC;
    transform: rotate(90deg);
}

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

.api-key-section {
    position: relative;
    margin-bottom: var(--spacing-md);
}

.api-key-section label {
    display: block;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--theme-text);
    margin-bottom: var(--spacing-xs);
}

.api-key-input {
    width: 100%;
    padding: 0.875rem 3rem 0.875rem 1rem;
    border: 2px solid #E2E8F0;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-family: 'Courier New', monospace;
    transition: all 0.3s ease;
}

.api-key-input:focus {
    outline: none;
    border-color: var(--theme-purple);
    box-shadow: 0 0 0 3px rgba(186, 166, 230, 0.2);
}

.btn-toggle-visibility {
    position: absolute;
    right: 8px;
    bottom: 8px;
    width: 36px;
    height: 36px;
    border: none;
    background: transparent;
    color: #718096;
    cursor: pointer;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

.btn-toggle-visibility:hover {
    background: #F7FAFC;
    color: var(--theme-text);
}

.btn-save {
    width: 100%;
    background: var(--gradient-primary);
    color: var(--theme-text);
    font-weight: 700;
}

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

/* ===== Responsive Design ===== */
@media (max-width: 640px) {
    .app-title {
        font-size: 2rem;
    }
    
    .settings-panel {
        flex-direction: column;
    }
    
    .setting-group {
        min-width: 100%;
    }
    
    .action-buttons {
        flex-direction: column;
    }
    
    .btn-camera {
        order: 2;
    }
    
    .btn-solve {
        order: 1;
    }
}

/* ===== Utility Classes ===== */
.text-center {
    text-align: center;
}

.mt-1 { margin-top: var(--spacing-xs); }
.mt-2 { margin-top: var(--spacing-sm); }
.mt-3 { margin-top: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-lg); }

.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }

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

/* ===== Print Styles ===== */
@media print {
    .header,
    .settings-panel,
    .action-buttons,
    .feedback-section,
    .footer {
        display: none;
    }
    
    .result-content {
        max-height: none;
    }
}