/* 
 * Sinopec Recharge Website Styles
 * A modern, responsive design for the Sinopec recharge service
 */

/* Base Styles and Variables */
:root {
    /* Primary Colors */
    --primary-color: #e50012; /* Sinopec red */
    --secondary-color: #005baa; /* Sinopec blue */
    --accent-color: #ffb400; /* Golden yellow */
    
    /* Neutral Colors */
    --dark: #333333;
    --medium: #666666;
    --light: #999999;
    --lighter: #eeeeee;
    --white: #ffffff;
    
    /* Utility Colors */
    --success: #27ae60;
    --warning: #f39c12;
    --error: #e74c3c;
    --info: #3498db;
    
    /* Typography */
    --font-primary: 'Noto Sans SC', sans-serif;
    --font-size-base: 16px;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --border-radius-sm: 4px;
    --border-radius-md: 8px;
    --border-radius-lg: 16px;
    
    /* Box Shadow */
    --box-shadow-light: 0 2px 5px rgba(0, 0, 0, 0.1);
    --box-shadow-medium: 0 5px 15px rgba(0, 0, 0, 0.1);
    --box-shadow-heavy: 0 10px 25px rgba(0, 0, 0, 0.15);
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-medium: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: var(--font-size-base);
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    color: var(--dark);
    line-height: 1.6;
    background-color: var(--white);
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: var(--secondary-color);
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-color);
}

ul {
    list-style: none;
}

img {
    max-width: 100%;
    height: auto;
}

/* Container */
.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Section Styles */
section {
    padding: var(--spacing-xl) 0;
}

.section-title {
    font-size: 2rem;
    text-align: center;
    margin-bottom: var(--spacing-xl);
    position: relative;
    color: var(--dark);
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background-color: var(--primary-color);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.8rem 1.8rem;
    border-radius: var(--border-radius-md);
    font-weight: 500;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-fast);
    border: none;
    font-size: 1rem;
}

.primary-btn {
    background-color: var(--primary-color);
    color: var(--white);
}

.primary-btn:hover {
    background-color: #c50010;
    color: var(--white);
    box-shadow: var(--box-shadow-medium);
}

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

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

/* Header Styles */
header {
    background-color: var(--white);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--box-shadow-light);
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
}

.logo {
    display: flex;
    align-items: center;
}

.logo img {
    height: 40px;
    margin-right: var(--spacing-sm);
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--secondary-color);
}

.logo h1 span {
    font-weight: 500;
    color: var(--primary-color);
}

nav ul {
    display: flex;
}

nav ul li {
    margin-left: var(--spacing-lg);
}

nav ul li a {
    position: relative;
    font-weight: 500;
    color: var(--dark);
    padding: var(--spacing-xs) 0;
}

nav ul li a:hover,
nav ul li a.active {
    color: var(--primary-color);
}

nav ul li a.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--primary-color);
}

.mobile-menu-btn {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--dark);
}

/* Hero Section */
.hero {
    background: linear-gradient(rgba(0, 91, 170, 0.8), rgba(0, 91, 170, 0.8)), url('images/hero-bg.jpg');
    background-size: cover;
    background-position: center;
    padding: var(--spacing-xl) 0;
    color: var(--white);
    position: relative;
    text-align: center;
    min-height: 500px;
    display: flex;
    align-items: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    padding: var(--spacing-lg);
}

.hero-content h2 {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
    font-weight: 700;
}

.hero-content p {
    font-size: 1.2rem;
    margin-bottom: var(--spacing-lg);
    opacity: 0.9;
}

.hero-content .btn {
    margin: 0 var(--spacing-sm);
}

/* Features Section */
.features {
    background-color: var(--white);
}

.feature-cards {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-lg);
}

.feature-card {
    background-color: var(--white);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-lg);
    text-align: center;
    box-shadow: var(--box-shadow-light);
    transition: transform var(--transition-medium), box-shadow var(--transition-medium);
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--box-shadow-medium);
}

.feature-card .icon {
    width: 70px;
    height: 70px;
    margin: 0 auto var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background-color: rgba(229, 0, 18, 0.1);
    color: var(--primary-color);
    font-size: 2rem;
}

.feature-card h3 {
    margin-bottom: var(--spacing-sm);
    font-size: 1.2rem;
    color: var(--dark);
}

.feature-card p {
    color: var(--medium);
    font-size: 0.95rem;
}

/* Recharge Section */
.recharge-section {
    background-color: var(--lighter);
    padding: var(--spacing-xl) 0;
}

.recharge-container {
    display: grid;
    grid-template-columns: 3fr 2fr;
    gap: var(--spacing-lg);
    align-items: flex-start;
}

.recharge-form {
    background-color: var(--white);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--box-shadow-light);
}

.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
    color: var(--dark);
}

.form-group input {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid var(--light);
    border-radius: var(--border-radius-sm);
    font-size: 1rem;
    transition: all 0.3s ease;
    background-color: #f9fafb;
    box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.05);
}

.form-group input:focus {
    border-color: var(--secondary-color);
    outline: none;
    background-color: #fff;
    box-shadow: 0 0 0 3px rgba(0, 91, 170, 0.1);
}

.form-group input.valid {
    border-color: var(--success);
    background-color: #f0fff4;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2327ae60' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='20 6 9 17 4 12'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 15px center;
    padding-right: 40px;
}

.form-group input.invalid {
    border-color: var(--error);
    background-color: #fff5f5;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%23e74c3c' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cline x1='18' y1='6' x2='6' y2='18'%3E%3C/line%3E%3Cline x1='6' y1='6' x2='18' y2='18'%3E%3C/line%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 15px center;
    padding-right: 40px;
}

.error-message {
    display: none;
    color: var(--error);
    font-size: 0.85rem;
    margin-top: 5px;
    transition: all 0.3s ease;
}

.form-group input.invalid + .error-message {
    display: block;
}

/* 输入框占位符文本样式 */
::placeholder {
    color: #aab;
    opacity: 0.7;
    transition: opacity 0.3s;
}

:focus::placeholder {
    opacity: 0.5;
}

.amount-options {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.amount-option {
    padding: 0.6rem;
    border: 1px solid var(--light);
    border-radius: var(--border-radius-sm);
    background-color: var(--white);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-weight: 500;
}

.amount-option:hover,
.amount-option.active {
    background-color: var(--primary-color);
    color: var(--white);
    border-color: var(--primary-color);
}

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

.verification-code input {
    width: 100%;
}

#getCodeBtn {
    padding: 0 var(--spacing-md);
    background-color: var(--secondary-color);
    color: var(--white);
    border: none;
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    font-size: 0.9rem;
    transition: all var(--transition-fast);
    white-space: nowrap;
    font-weight: 500;
    min-width: 110px;
}

#getCodeBtn:hover {
    background-color: #004e91;
    transform: translateY(-2px);
    box-shadow: var(--box-shadow-light);
}

#getCodeBtn:disabled {
    background-color: var(--light);
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.payment-options {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-md);
}

.payment-option {
    position: relative;
    padding: var(--spacing-md);
    border: 1px solid var(--light);
    border-radius: var(--border-radius-sm);
    display: flex;
    flex-direction: column;
    align-items: center;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.payment-option input[type="radio"] {
    position: absolute;
    opacity: 0;
}

.payment-option label {
    cursor: pointer;
    text-align: center;
    margin: 0;
}

.payment-option label i {
    display: block;
    font-size: 1.5rem;
    margin-bottom: var(--spacing-xs);
    color: var(--medium);
}

.payment-option:hover {
    border-color: var(--secondary-color);
}

.payment-option input[type="radio"]:checked + label i {
    color: var(--primary-color);
}

.payment-option input[type="radio"]:checked + label {
    color: var(--primary-color);
}

.payment-option input[type="radio"]:checked ~ .payment-option {
    border-color: var(--primary-color);
    background-color: rgba(229, 0, 18, 0.05);
}

.submit-btn {
    width: 100%;
    padding: 1rem;
    font-size: 1.1rem;
    margin-top: var(--spacing-md);
}

.recharge-info {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.card {
    background-color: var(--white);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--box-shadow-light);
}

.info-card h3,
.promotion-card h3 {
    margin-bottom: var(--spacing-md);
    display: flex;
    align-items: center;
    color: var(--dark);
}

.info-card h3 i,
.promotion-card h3 i {
    margin-right: var(--spacing-sm);
    color: var(--primary-color);
}

.info-card ul li {
    margin-bottom: var(--spacing-sm);
    padding-left: var(--spacing-md);
    position: relative;
    color: var(--medium);
}

.info-card ul li:before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--primary-color);
}

.promotion-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--primary-color);
}

.promotion-period {
    font-size: 0.9rem;
    color: var(--medium);
    margin-bottom: var(--spacing-md);
}

.promotion-link {
    display: inline-block;
    color: var(--secondary-color);
    font-weight: 500;
}

.promotion-link i {
    margin-left: var(--spacing-xs);
    transition: transform var(--transition-fast);
}

.promotion-link:hover i {
    transform: translateX(5px);
}

/* Download App Section */
.download-app {
    background: linear-gradient(to right, var(--primary-color), var(--secondary-color));
    color: var(--white);
    padding: var(--spacing-xl) 0;
}

.download-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-xl);
}

.download-info {
    flex: 1;
}

.download-info h2 {
    font-size: 2rem;
    margin-bottom: var(--spacing-md);
}

.app-features {
    margin: var(--spacing-lg) 0;
}

.app-features li {
    margin-bottom: var(--spacing-sm);
    display: flex;
    align-items: center;
}

.app-features li i {
    margin-right: var(--spacing-sm);
    color: var(--accent-color);
}

.download-buttons {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.download-btn {
    display: flex;
    align-items: center;
    background-color: var(--dark);
    color: var(--white);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--border-radius-md);
    transition: all var(--transition-fast);
}

.download-btn:hover {
    background-color: var(--white);
    color: var(--primary-color);
    transform: translateY(-3px);
}

.download-btn i {
    font-size: 2rem;
    margin-right: var(--spacing-sm);
}

.download-btn span {
    text-align: left;
    line-height: 1.2;
}

.app-qrcode {
    text-align: center;
}

.app-qrcode img {
    width: 180px;
    height: 180px;
    background-color: var(--white);
    padding: var(--spacing-sm);
    border-radius: var(--border-radius-md);
    margin-bottom: var(--spacing-sm);
}

.app-qrcode p {
    font-size: 0.9rem;
}

/* FAQ Section */
.faq-section {
    background-color: var(--white);
}

.faq-container {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    border-bottom: 1px solid var(--lighter);
    margin-bottom: var(--spacing-md);
}

.faq-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
    cursor: pointer;
}

.faq-question h3 {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--dark);
}

.faq-question i {
    color: var(--primary-color);
    transition: transform var(--transition-fast);
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
}

.faq-answer {
    padding: 0 0 var(--spacing-md);
    display: none;
    color: var(--medium);
}

.faq-item.active .faq-answer {
    display: block;
}

.more-help {
    text-align: center;
    margin-top: var(--spacing-xl);
}

.more-help p {
    margin-bottom: var(--spacing-md);
    color: var(--medium);
}

/* Footer */
footer {
    background-color: #1a1a1a;
    color: var(--white);
    padding: var(--spacing-xl) 0 var(--spacing-md);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.footer-column h3 {
    color: var(--white);
    margin-bottom: var(--spacing-lg);
    position: relative;
    font-size: 1.2rem;
    padding-bottom: var(--spacing-sm);
}

.footer-column h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 40px;
    height: 2px;
    background-color: var(--primary-color);
}

.about-us p {
    color: var(--light);
    margin-bottom: var(--spacing-md);
    font-size: 0.9rem;
    line-height: 1.6;
}

.social-media {
    display: flex;
    gap: var(--spacing-md);
}

.social-media a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--white);
    transition: all var(--transition-fast);
}

.social-media a:hover {
    background-color: var(--primary-color);
    transform: translateY(-3px);
}

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

.quick-links ul li a {
    color: var(--light);
    transition: color var(--transition-fast), padding-left var(--transition-fast);
    display: block;
}

.quick-links ul li a:hover {
    color: var(--white);
    padding-left: var(--spacing-sm);
}

.contact-info ul li {
    display: flex;
    margin-bottom: var(--spacing-md);
    color: var(--light);
}

.contact-info ul li i {
    margin-right: var(--spacing-sm);
    color: var(--primary-color);
    min-width: 20px;
}

.newsletter p {
    color: var(--light);
    margin-bottom: var(--spacing-md);
    font-size: 0.9rem;
}

.newsletter-form {
    display: flex;
    height: 44px;
}

.newsletter-form input {
    flex: 1;
    padding: 0 var(--spacing-md);
    border: none;
    border-radius: var(--border-radius-sm) 0 0 var(--border-radius-sm);
    font-size: 0.9rem;
}

.newsletter-form button {
    width: 44px;
    background-color: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: 0 var(--border-radius-sm) var(--border-radius-sm) 0;
    cursor: pointer;
    transition: background-color var(--transition-fast);
}

.newsletter-form button:hover {
    background-color: #c50010;
}

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    font-size: 0.9rem;
}

.footer-bottom p {
    color: var(--light);
}

.footer-bottom-links {
    display: flex;
}

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

.footer-bottom-links li a {
    color: var(--light);
}

.footer-bottom-links li a:hover {
    color: var(--white);
}

/* Responsive Design */
@media screen and (max-width: 1024px) {
    .feature-cards {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .download-content {
        flex-direction: column;
        text-align: center;
    }
    
    .app-features li {
        justify-content: center;
    }
    
    .download-buttons {
        justify-content: center;
    }
}

@media screen and (max-width: 768px) {
    .container {
        width: 95%;
    }
    
    .logo h1 {
        font-size: 1.2rem;
    }
    
    nav {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 80%;
        height: calc(100% - 70px);
        background-color: var(--white);
        box-shadow: var(--box-shadow-medium);
        transition: left var(--transition-medium);
        z-index: 999;
    }
    
    nav.active {
        left: 0;
    }
    
    nav ul {
        flex-direction: column;
        padding: var(--spacing-lg);
    }
    
    nav ul li {
        margin: var(--spacing-sm) 0;
    }
    
    nav ul li a {
        display: block;
        padding: var(--spacing-sm) 0;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .hero-content h2 {
        font-size: 2rem;
    }
    
    .recharge-container {
        grid-template-columns: 1fr;
    }
    
    .payment-options {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }
    
    .footer-bottom {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }
    
    .footer-bottom-links {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .footer-bottom-links li {
        margin: 0;
    }
}

@media screen and (max-width: 576px) {
    .section-title {
        font-size: 1.5rem;
    }
    
    .feature-cards {
        grid-template-columns: 1fr;
    }
    
    .hero-content .btn {
        display: block;
        width: 100%;
        margin: var(--spacing-sm) 0;
    }
    
    .amount-options {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .verification-code {
        flex-direction: column;
    }
    
    #getCodeBtn {
        width: 100%;
        padding: 0.8rem;
    }
    
    .download-buttons {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .download-btn {
        width: 100%;
        justify-content: center;
    }
    
    .captcha-container {
        width: 100%;
    }
}

/* 为卡密充值表单添加样式 */
.form-hint {
    font-size: 0.85rem;
    color: var(--medium);
    margin-top: var(--spacing-xs);
}

.purchase-card h3 {
    margin-bottom: var(--spacing-md);
    display: flex;
    align-items: center;
    color: var(--dark);
}

.purchase-card h3 i {
    margin-right: var(--spacing-sm);
    color: var(--primary-color);
}

.purchase-options p {
    margin-bottom: var(--spacing-md);
    color: var(--medium);
}

.purchase-options ul {
    margin-bottom: var(--spacing-md);
}

.purchase-options ul li {
    margin-bottom: var(--spacing-sm);
    display: flex;
    align-items: center;
    color: var(--medium);
}

.purchase-options ul li i {
    margin-right: var(--spacing-sm);
    color: var(--secondary-color);
    min-width: 20px;
}

.captcha-wrapper {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 5px;
}

.captcha-container {
    display: flex;
    align-items: center;
    gap: 5px;
    height: 38px;
}

.captcha-image {
    height: 38px;
    width: 100px;
    background-color: var(--white);
    border-radius: var(--border-radius-sm);
    border: 1px solid var(--light);
    box-shadow: inset 0 0 4px rgba(0, 0, 0, 0.05);
    transition: all var(--transition-medium);
    opacity: 1;
    object-fit: contain;
}

.captcha-image:hover {
    border-color: var(--secondary-color);
}

.refresh-captcha {
    width: 30px;
    height: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--white);
    color: var(--secondary-color);
    border: 1px solid var(--light);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    transition: all var(--transition-medium);
    overflow: hidden;
    position: relative;
    flex-shrink: 0;
}

.refresh-captcha:hover {
    background-color: var(--secondary-color);
    color: var(--white);
    border-color: var(--secondary-color);
    transform: rotate(180deg);
}

.refresh-captcha i {
    font-size: 0.9rem;
}

/* Add a nice label for accessibility */
.form-group:has(.captcha-container) .form-hint {
    display: block;
    margin-top: var(--spacing-sm);
    font-style: italic;
    color: var(--medium);
}

#verificationCode {
    font-size: 1rem;
    letter-spacing: 0.1em;
    text-align: center;
    font-weight: 500;
    color: var(--dark);
    background-color: var(--white);
    border: 1px solid var(--light);
    border-radius: var(--border-radius-sm);
    transition: all var(--transition-fast);
    padding: 0.6rem;
    width: 120px;
    height: 38px;
    box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.05);
}

#verificationCode:focus {
    border-color: var(--secondary-color);
    box-shadow: inset 0 1px 3px rgba(0, 91, 170, 0.1);
    outline: none;
}

/* Add a spinning animation for the refresh button */
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.fa-spin {
    animation: spin 1s linear infinite;
}

/* Add a gentle shake animation for invalid input */
@keyframes shake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
    20%, 40%, 60%, 80% { transform: translateX(5px); }
}

.shake {
    animation: shake 0.6s cubic-bezier(0.36, 0.07, 0.19, 0.97) both;
}

/* Add a smooth success animation */
@keyframes success-pulse {
    0% { box-shadow: 0 0 0 0 rgba(39, 174, 96, 0.4); }
    70% { box-shadow: 0 0 0 10px rgba(39, 174, 96, 0); }
    100% { box-shadow: 0 0 0 0 rgba(39, 174, 96, 0); }
}

.success-pulse {
    animation: success-pulse 1.5s 1;
}