/* ==========================================================================
   AIadmit.ai - Modern Educational Platform Styles
   ========================================================================== */

/* Global Variables */
:root {
    /* Color Palette */
    --primary-color: #0066cc;
    --primary-light: #4d94ff;
    --primary-dark: #004999;
    --secondary-color: #00a86b;
    --secondary-light: #33d492;
    --secondary-dark: #008055;
    --accent-color: #8b5cf6;
    --dark-color: #1e293b;
    --dark-light: #334155;
    --gray-color: #64748b;
    --gray-light: #f1f5f9;
    --gray-border: #e2e8f0;
    --white: #ffffff;
    --error-color: #ef4444;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    
    /* Typography - Microsoft YaHei for Chinese, system fonts for English */
    --font-primary: 'Microsoft YaHei', sans-serif;
    --font-secondary: 'Microsoft YaHei', serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    
    /* Box Shadow */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

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

/* Background Effects */
/* body::before removed as requested - no global background image */

/* Container */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-primary);
    font-weight: 600;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

h1 {
    font-size: 3rem;
    font-weight: 700;
}

h2 {
    font-size: 2.25rem;
}

h3 {
    font-size: 1.75rem;
}

h4 {
    font-size: 1.5rem;
}

p {
    margin-bottom: var(--spacing-md);
    font-size: 1.125rem;
    color: var(--dark-light);
}

.section-title {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    color: var(--dark-color);
}

/* Navigation */
.navbar {
    background-color: var(--white);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: var(--spacing-sm) 0;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.logo-image {
    height: 40px;
    width: auto;
    max-width: 200px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
    align-items: center;
}

.nav-links a {
    position: relative;
    text-decoration: none;
    color: var(--dark-color);
    font-weight: 500;
    transition: color var(--transition-normal), border-color var(--transition-normal), background-color var(--transition-normal), box-shadow var(--transition-normal);
}

.nav-links a.active:not(.btn-primary) {
    color: var(--primary-color);
}

.nav-links a.active:not(.btn-primary)::after {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    bottom: -0.45rem;
    height: 2px;
    border-radius: 999px;
    background: linear-gradient(90deg, var(--primary-color) 0%, var(--secondary-color) 100%);
}

/* 导航栏中的Request Demo按钮 - 灰色字体，小尺寸 */
.nav-links .btn-primary {
    color: #666666;
    background: transparent;
    border: 2px solid var(--primary-color);
    position: relative;
    z-index: 0;
    isolation: isolate;
    overflow: hidden;
    padding: 0.5rem 1.25rem;
    font-size: 0.9rem;
    min-height: 38px;
    transition: color var(--transition-normal), border-color var(--transition-normal);
}

.nav-links .btn-primary:hover {
    color: var(--white);
    border-color: var(--primary-color);
    transform: none;
    box-shadow: var(--shadow-md);
}

.nav-links .btn-primary.active {
    color: var(--white);
    border-color: var(--primary-color);
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    box-shadow: 0 10px 20px rgba(0, 102, 204, 0.18);
}

.nav-links .btn-primary::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    transform: translateX(-100%);
    transition: transform var(--transition-normal);
    z-index: -1;
}

.nav-links .btn-primary:hover::before {
    transform: translateX(0);
}

.nav-links .btn-primary.active::before {
    transform: translateX(0);
    opacity: 0;
}

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

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

/* Buttons */
.btn-primary, .btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: 0.875rem 2rem;
    font-family: var(--font-primary);
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all var(--transition-normal);
    cursor: pointer;
    border: none;
    outline: none;
    min-height: 48px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: var(--white);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--primary-color) 100%);
}

.btn-primary:active {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.field-error {
    min-height: 1.25rem;
    margin-top: 0.4rem;
    margin-bottom: 0;
    font-size: 0.875rem;
    color: var(--error-color);
}

.btn-secondary {
    background-color: transparent;
    color: #666666; /* 灰色字体 */
    border: 2px solid var(--primary-color);
    position: relative;
    z-index: 0;
    isolation: isolate;
    overflow: hidden;
}

.btn-secondary::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    transform: translateX(-100%);
    transition: transform var(--transition-normal);
    z-index: -1;
}

.btn-secondary:hover {
    color: var(--white);
    border-color: var(--primary-color);
}

.btn-secondary:hover::before {
    transform: translateX(0);
}

/* Button Icons */
.btn-icon {
    font-size: 1.1rem;
    transition: transform var(--transition-normal);
}

.btn-primary:hover .btn-icon,
.btn-secondary:hover .btn-icon {
    transform: translateY(-2px);
}

/* Button sizes */
.btn-small {
    padding: 0.625rem 1.5rem;
    font-size: 0.9rem;
    min-height: 40px;
}

.btn-large {
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    min-height: 56px;
}

/* Button loading state */
.btn-primary.loading,
.btn-secondary.loading {
    position: relative;
    color: transparent;
}

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

.btn-secondary.loading::after {
    border: 3px solid rgba(0, 102, 204, 0.3);
    border-top-color: var(--primary-color);
}

@keyframes button-spinner {
    to {
        transform: translate(-50%, -50%) rotate(360deg);
    }
}

/* Disabled state */
.btn-primary:disabled,
.btn-secondary:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
    box-shadow: none !important;
}

.btn-primary:disabled:hover {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
}

.btn-secondary:disabled:hover {
    background-color: transparent;
    color: var(--primary-color);
}

.btn-secondary:disabled:hover::before {
    transform: translateX(-100%);
}

/* Hero Section */
.hero {
    padding: var(--spacing-xl) 0;
    min-height: 85vh;
    display: flex;
    align-items: center;
    background: 
        linear-gradient(135deg, rgba(255, 255, 255, 0.7) 0%, rgba(248, 250, 252, 0.65) 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        url('../images/downloadedSIS.jpg') center/cover no-repeat;
    z-index: -1;
    pointer-events: none;
    opacity: 1;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--dark-color);
    margin-bottom: var(--spacing-md);
    line-height: 1.1;
}

.hero-subtitle {
    font-size: 1.375rem;
    color: var(--gray-color);
    margin-bottom: var(--spacing-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

/* Features Section */
.features {
    padding: var(--spacing-xl) 0;
    background-color: var(--white);
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.feature-card {
    background: var(--white);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-md);
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
    border: 1px solid var(--gray-border);
    position: relative;
    overflow: hidden;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(to bottom, var(--primary-color), var(--secondary-color));
}

.feature-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
}

.feature-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--dark-color);
}

.feature-description {
    color: var(--gray-color);
    font-size: 1rem;
    line-height: 1.5;
}

/* About Section */
.about {
    padding: var(--spacing-xl) 0;
    background: linear-gradient(135deg, rgba(0, 102, 204, 0.03) 0%, rgba(0, 168, 107, 0.02) 100%);
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.about-text {
    font-size: 1.25rem;
    line-height: 1.7;
    margin-bottom: var(--spacing-xl);
}

.about-stats {
    display: flex;
    justify-content: center;
    gap: var(--spacing-xl);
    flex-wrap: wrap;
    margin-top: var(--spacing-xl);
}

.stat-item {
    text-align: center;
    padding: var(--spacing-md);
    min-width: 180px;
}

.stat-number {
    font-size: 3rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: 1rem;
    color: var(--gray-color);
    font-weight: 500;
}

/* Contact Section */
.contact {
    padding: var(--spacing-xl) 0;
    background-color: var(--white);
}

.contact-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.contact-info {
    padding: var(--spacing-lg);
    background: linear-gradient(135deg, var(--gray-light) 0%, var(--white) 100%);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.contact-title {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-lg);
    color: var(--dark-color);
}

.contact-details {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.contact-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.contact-icon {
    font-size: 1.25rem;
    color: var(--primary-color);
}

.contact-item p {
    margin: 0;
    font-size: 1rem;
}

.contact-form {
    padding: var(--spacing-lg);
    background: var(--white);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--gray-border);
}

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

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

.form-input,
.form-textarea {
    width: 100%;
    padding: 0.875rem;
    border: 1px solid var(--gray-border);
    border-radius: var(--radius-md);
    font-family: var(--font-secondary);
    font-size: 1rem;
    transition: border-color var(--transition-normal);
    background-color: var(--gray-light);
}

.form-input:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    background-color: var(--white);
}

.form-textarea {
    min-height: 150px;
    resize: vertical;
}

.form-error {
    color: var(--error-color);
    font-size: 0.875rem;
    margin-top: var(--spacing-xs);
    display: none;
}

.form-success {
    color: var(--success-color);
    font-size: 0.875rem;
    margin-top: var(--spacing-xs);
    display: none;
}

/* Footer */
.footer {
    background-color: var(--dark-color);
    color: var(--white);
    padding: var(--spacing-xl) 0;
    margin-top: var(--spacing-xl);
}

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

.footer-logo .logo-image {
    filter: brightness(0) invert(1);
}

.footer-links {
    display: flex;
    gap: var(--spacing-lg);
    list-style: none;
}

.footer-links a {
    color: var(--gray-light);
    text-decoration: none;
    transition: color var(--transition-normal);
}

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

.copyright {
    color: var(--gray-color);
    font-size: 0.875rem;
    text-align: center;
    margin-top: var(--spacing-lg);
}

/* Responsive Design */
@media (max-width: 768px) {
    html {
        font-size: 14px;
    }
    
    h1 {
        font-size: 2.5rem;
    }
    
    h2 {
        font-size: 2rem;
    }
    
    .hero-title {
        font-size: 2.75rem;
    }
    
    .hero-subtitle {
        font-size: 1.25rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: var(--white);
        flex-direction: column;
        padding: var(--spacing-md);
        box-shadow: var(--shadow-lg);
    }
    
    .nav-links.active {
        display: flex;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .feature-grid {
        grid-template-columns: 1fr;
    }
    
    .about-stats {
        gap: var(--spacing-lg);
    }
    
    .stat-item {
        min-width: 140px;
    }
    
    .stat-number {
        font-size: 2.5rem;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
        gap: var(--spacing-md);
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 2rem;
    }
    
    h2 {
        font-size: 1.75rem;
    }
    
    .hero-title {
        font-size: 2.25rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .btn-primary, .btn-secondary {
        padding: 0.75rem 1.5rem;
        font-size: 0.9rem;
        width: 100%;
    }
    
    .contact-container {
        grid-template-columns: 1fr;
    }
}