:root {
    --primary-gradient: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
    --bg-color: #ffffff;
    --container-bg: #ffffff;
    --text-color: #333333;
    --text-secondary: #666666;
    --border-color: #e0e0e0;
    --input-bg: #ffffff;
    --preview-bg: #f8f9fa;
    --shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    --modal-overlay: rgba(0, 0, 0, 0.5);
}

[data-theme="dark"] {
    --bg-color: #1a1a2e;
    --container-bg: #16213e;
    --text-color: #eaeaea;
    --text-secondary: #b0b0b0;
    --border-color: #2a2a3e;
    --input-bg: #0f1624;
    --preview-bg: #0f1624;
    --shadow: 0 20px 60px rgba(0, 0, 0, 0.6);
    --modal-overlay: rgba(0, 0, 0, 0.8);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--primary-gradient);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
    transition: background 0.3s ease;
}

.theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--container-bg);
    border: 2px solid var(--border-color);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    transition: all 0.3s ease;
    z-index: 1000;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
}

.theme-toggle:hover {
    transform: scale(1.1) rotate(15deg);
}

.theme-toggle .moon-icon {
    display: none;
}

[data-theme="dark"] .theme-toggle .sun-icon {
    display: none;
}

[data-theme="dark"] .theme-toggle .moon-icon {
    display: block;
}

.container {
    background: var(--container-bg);
    border-radius: 20px;
    box-shadow: var(--shadow);
    padding: 40px;
    max-width: 500px;
    width: 100%;
    transition: all 0.3s ease;
}

h1 {
    color: var(--text-color);
    margin-bottom: 10px;
    font-size: 28px;
    text-align: center;
}

.subtitle {
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: 30px;
    font-size: 14px;
}

.form-group {
    margin-bottom: 25px;
}

label {
    display: block;
    margin-bottom: 8px;
    color: var(--text-color);
    font-weight: 600;
    font-size: 14px;
}

select, input[type="email"], input[type="text"] {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    font-size: 16px;
    color: var(--text-color);
    background-color: var(--input-bg);
    transition: all 0.3s ease;
}

select {
    cursor: pointer;
}

select:hover, input[type="email"]:hover, input[type="text"]:hover {
    border-color: #2a5298;
}

select:focus, input[type="email"]:focus, input[type="text"]:focus {
    outline: none;
    border-color: #2a5298;
    box-shadow: 0 0 0 3px rgba(42, 82, 152, 0.1);
}

input[type="email"].error, input[type="text"].error {
    border-color: #e74c3c;
}

.error-message {
    color: #e74c3c;
    font-size: 12px;
    margin-top: 5px;
    display: none;
}

.error-message.show {
    display: block;
}

.preview-section {
    margin: 25px 0;
    padding: 20px;
    background: var(--preview-bg);
    border-radius: 10px;
    text-align: center;
    border: 2px solid var(--border-color);
}

.preview-label {
    font-size: 12px;
    color: var(--text-secondary);
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.preview-text {
    font-size: 32px;
    color: var(--text-color);
    min-height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
}

button {
    width: 100%;
    padding: 15px;
    background: var(--primary-gradient);
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    margin-top: 10px;
}

button:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(42, 82, 152, 0.3);
}

button:active {
    transform: translateY(0);
}

button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

.loading {
    display: none;
    text-align: center;
    margin-top: 15px;
    color: #2a5298;
    font-size: 14px;
}

.loading.active {
    display: block;
}

.success-message {
    display: none;
    text-align: center;
    margin-top: 15px;
    padding: 15px;
    background: #d4edda;
    color: #155724;
    border-radius: 10px;
    font-size: 14px;
}

.success-message.show {
    display: block;
}

.font-count {
    text-align: center;
    font-size: 12px;
    color: var(--text-secondary);
    margin-top: 5px;
}

/* Modal styles */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: var(--modal-overlay);
    justify-content: center;
    align-items: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--container-bg);
    padding: 40px;
    border-radius: 20px;
    max-width: 450px;
    width: 90%;
    box-shadow: var(--shadow);
}

.modal-title {
    font-size: 24px;
    color: var(--text-color);
    margin-bottom: 10px;
    text-align: center;
}

.modal-subtitle {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 25px;
    text-align: center;
}

.modal-buttons {
    display: flex;
    gap: 10px;
    margin-top: 20px;
}

.modal-buttons button {
    flex: 1;
    margin-top: 0;
}

.btn-secondary {
    background: var(--border-color);
    color: var(--text-color);
}

.btn-secondary:hover {
    background: #d0d0d0;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.resend-code {
    text-align: center;
    font-size: 14px;
    color: var(--text-secondary);
    margin-top: 15px;
}

.link-btn {
    background: none;
    color: #2a5298;
    border: none;
    padding: 0;
    font-size: 14px;
    text-decoration: underline;
    cursor: pointer;
    width: auto;
    display: inline;
    margin: 0;
}

.link-btn:hover {
    color: #1e3c72;
    transform: none;
    box-shadow: none;
}

/* A4 Paper Container */
#a4-container {
    position: absolute;
    left: -9999px;
    top: 0;
    width: 210mm;
    height: 297mm;
    background: white;
    padding: 20mm;
    padding-bottom: 20mm;
    box-sizing: border-box;
    overflow: hidden;
}

.practice-line {
    position: relative;
    width: 100%;
}

.practice-text {
    color: #c0c0c0;
    line-height: 1.2;
    margin-bottom: 2mm;
}

.guide-line {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 2px;
    background-color: #000;
}

.worksheet-title {
    text-align: center;
    font-size: 20px;
    color: #333;
    margin-bottom: 8mm;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-weight: bold;
}

.worksheet-watermark {
    position: absolute;
    bottom: 5mm;
    left: 0;
    right: 0;
    text-align: center;
    font-size: 10px;
    color: #999;
    font-style: italic;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

/* Verification Code Input Styling */
#verification-code {
    text-align: center;
    font-size: 24px;
    letter-spacing: 8px;
    font-weight: bold;
}

/* Buy Me a Coffee Modal Styles */
.coffee-content {
    text-align: center;
}

.coffee-message {
    background: var(--preview-bg);
    padding: 20px;
    border-radius: 10px;
    margin: 20px 0;
    border: 2px solid var(--border-color);
}

.coffee-message p {
    color: var(--text-secondary);
    font-size: 14px;
    line-height: 1.6;
    margin: 0;
}

.coffee-footer {
    text-align: center;
    font-size: 12px;
    color: var(--text-secondary);
    margin-top: 15px;
    margin-bottom: 0;
}

#coffee-support-btn {
    background: linear-gradient(135deg, #FFDD00 0%, #FBB034 100%);
    color: #000;
    font-weight: bold;
}

#coffee-support-btn:hover {
    background: linear-gradient(135deg, #FBB034 0%, #FFDD00 100%);
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(251, 176, 52, 0.4);
}

.coffee-content a {
    text-decoration: none;
    display: block;
    flex: 1;
}

/* Watermark Styles */
.worksheet-watermark {
    text-align: center;
    font-size: 12px;
    color: #999;
    margin-top: 15mm;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-style: italic;
}

/* Stats Badge */
.stats-badge {
    text-align: center;
    margin: -15px auto 25px auto;
    padding: 10px 20px;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(42, 82, 152, 0.1) 100%);
    border-radius: 20px;
    font-size: 13px;
    color: var(--text-secondary);
    display: inline-block;
    width: auto;
}

.stats-icon {
    font-size: 16px;
    margin-right: 5px;
}

#download-count {
    font-weight: bold;
    color: #2a5298;
    font-size: 16px;
}

[data-theme="dark"] #download-count {
    color: #667eea;
}

/* Content and Pages Info */
.content-info, .pages-info {
    text-align: center;
    font-size: 12px;
    color: var(--text-secondary);
    margin-top: 8px;
    font-style: italic;
}

#size-estimate {
    font-weight: bold;
    color: #2a5298;
}

[data-theme="dark"] #size-estimate {
    color: #667eea;
}

/* Preview Modal */
.preview-modal-content {
    max-width: 800px;
    max-height: 90vh;
    overflow-y: auto;
}

.preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.close-preview {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--text-color);
    width: auto;
    padding: 5px 10px;
    margin: 0;
}

.close-preview:hover {
    color: #e74c3c;
    transform: none;
    box-shadow: none;
}

.preview-container {
    position: relative;
    background: #f5f5f5;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    padding: 20px;
    margin-bottom: 20px;
    overflow: auto;
    max-height: 500px;
}

.preview-watermark-overlay {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%) rotate(-45deg);
    font-size: 80px;
    font-weight: bold;
    color: rgba(0, 0, 0, 0.05);
    pointer-events: none;
    z-index: 10;
    letter-spacing: 20px;
}

#preview-canvas {
    display: block;
    max-width: 100%;
    height: auto;
    margin: 0 auto;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.preview-info {
    background: var(--preview-bg);
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 20px;
}

.preview-info p {
    margin: 8px 0;
    font-size: 14px;
    color: var(--text-color);
}

.preview-info strong {
    color: var(--text-secondary);
}

.preview-info span {
    color: var(--text-color);
    font-weight: 500;
}