/* ============================================
   新纪元英语词汇系统 - 全局样式
   ============================================ */

/* CSS Variables */
:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --secondary-color: #10b981;
    --secondary-hover: #059669;
    --danger-color: #f43f5e;
    --warning-color: #f59e0b;
    --dark-color: #1e293b;
    --light-color: #f8fafc;
    --border-radius: 1rem;
    --transition: all 0.3s ease;
}

/* Base Styles */
* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.3;
}

/* Utility Classes */
.text-gradient {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Card Hover Effects */
.login-card {
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.login-card:hover {
    transform: translateY(-5px);
}

.stat-card {
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
}

/* Form Elements */
input:focus,
select:focus,
textarea:focus {
    outline: none;
}

/* Button Base */
button {
    cursor: pointer;
    transition: var(--transition);
}

button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

/* Navigation Tab Active State */
.nav-tab-active {
    border-bottom: 3px solid var(--primary-color);
    color: var(--primary-color);
    font-weight: 600;
}

/* Table Styles */
table {
    border-collapse: collapse;
}

th {
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.75rem;
    letter-spacing: 0.05em;
}

tbody tr {
    transition: background-color 0.15s ease;
}

/* Scrollbar Styles */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: #f1f5f9;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: #cbd5e1;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: #94a3b8;
}

/* Loading Animation */
@keyframes loading {
    0% {
        width: 0%;
        margin-left: 0;
    }
    50% {
        width: 50%;
        margin-left: 25%;
    }
    100% {
        width: 0%;
        margin-left: 100%;
    }
}

/* Selection Color */
::selection {
    background-color: rgba(79, 70, 229, 0.2);
    color: #1e293b;
}

/* Focus Visible */
:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Responsive Typography */
@media (max-width: 640px) {
    html {
        font-size: 14px;
    }
}

/* Print Styles */
@media print {
    nav,
    button,
    .no-print {
        display: none !important;
    }
    
    body {
        background: white;
    }
}

/* 3D Card Flip Styles */
.preserve-3d {
    transform-style: preserve-3d;
    perspective: 1000px;
}

.backface-hidden {
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    -moz-backface-visibility: hidden;
    -ms-backface-visibility: hidden;
}

.rotate-y-0 {
    transform: rotateY(0deg);
}

.rotate-y-180 {
    transform: rotateY(180deg);
}

#flashcard-container {
    transition: transform 0.6s;
    transform-style: preserve-3d;
}

#flashcard-container > div {
    position: absolute;
    width: 100%;
    height: 100%;
    transition: transform 0.6s;
}

/* Flashcard Mode Specific Styles */
#flashcard-mode {
    backdrop-filter: blur(10px);
    background: rgba(0, 0, 0, 0.8);
}

#flashcard-mode .preserve-3d {
    perspective: 1200px;
}

#flashcard-mode .backface-hidden {
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
}

/* Progress Bar Animation */
#flashcard-progress-bar {
    transition: width 0.3s ease-in-out;
}

/* Responsive Card Sizes */
@media (max-width: 768px) {
    #flashcard-mode .max-w-2xl {
        max-width: 90%;
    }
    
    #flashcard-mode h2 {
        font-size: 1.5rem;
    }
    
    #flashcard-mode .text-6xl {
        font-size: 2.5rem;
    }
}

@media (max-width: 640px) {
    #flashcard-mode .text-6xl {
        font-size: 2rem;
    }
    
    #flashcard-mode .p-8 {
        padding: 1.5rem;
    }
}