:root {
    /* 纯净淡雅主题色系 */
    --primary-color: #667eea;
    --primary-hover: #5a6fd8;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    --success-color: #4facfe;
    --warning-color: #43e97b;

    /* 纯净渐变色 */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-hover: linear-gradient(135deg, #5a6fd8 0%, #6a4190 100%);
    --gradient-accent: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --gradient-soft: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
    --gradient-blue: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);

    /* 背景与文本 */
    --bg-color: #fafbff;
    --text-main: #2d3748;
    --text-muted: #718096;
    --text-light: #a0aec0;

    /* 玻璃拟态卡片 */
    --card-bg: rgba(255, 255, 255, 0.85);
    --card-border: rgba(255, 255, 255, 0.9);
    --card-shadow: 0 20px 60px -10px rgba(102, 126, 234, 0.15);
    --card-shadow-hover: 0 30px 80px -10px rgba(102, 126, 234, 0.25);

    /* 组件背景 */
    --input-bg: rgba(255, 255, 255, 0.95);
    --upload-area-bg: rgba(247, 250, 252, 0.8);

    /* 动画参数 */
    --animation-speed: 0.4s;
    --bounce: cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Noto Sans CJK SC", "Microsoft YaHei", sans-serif;
    background: var(--bg-color);
    background-image:
        radial-gradient(circle at 25% 25%, rgba(102, 126, 234, 0.02) 0%, transparent 50%),
        radial-gradient(circle at 75% 75%, rgba(240, 147, 251, 0.02) 0%, transparent 50%);
    color: var(--text-main);
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
    line-height: 1.65;
    font-weight: 400;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* --- 炫酷且高效的动态背景 (纯CSS实现) --- */
.background-animation {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    overflow: hidden;
    background: linear-gradient(135deg, #fafbff 0%, #f7fafc 100%);
}

.shape {
    position: absolute;
    filter: blur(100px);
    opacity: 0.7;
    animation: float 25s infinite ease-in-out;
    border-radius: 50%;
    will-change: transform;
}

.shape-1 {
    top: -15%;
    left: -15%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(102, 126, 234, 0.2) 0%, rgba(102, 126, 234, 0.05) 40%, transparent 70%);
    animation-delay: -5s;
}

.shape-2 {
    bottom: -15%;
    right: -10%;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(240, 147, 251, 0.18) 0%, rgba(240, 147, 251, 0.04) 40%, transparent 70%);
    animation-delay: -12s;
}

.shape-3 {
    top: 35%;
    left: 45%;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(79, 172, 254, 0.15) 0%, rgba(79, 172, 254, 0.03) 40%, transparent 70%);
    animation-delay: -8s;
}

.shape-4 {
    top: 10%;
    right: 20%;
    width: 350px;
    height: 350px;
    background: radial-gradient(circle, rgba(67, 233, 123, 0.12) 0%, rgba(67, 233, 123, 0.02) 40%, transparent 70%);
    animation-delay: -15s;
}

@keyframes float {
    0% {
        transform: translate(0, 0) rotate(0deg) scale(1);
    }
    25% {
        transform: translate(30px, -40px) rotate(5deg) scale(1.05);
    }
    50% {
        transform: translate(-20px, 30px) rotate(-3deg) scale(0.95);
    }
    75% {
        transform: translate(40px, 20px) rotate(7deg) scale(1.02);
    }
    100% {
        transform: translate(10px, -10px) rotate(-2deg) scale(1);
    }
}

/* --- 卡片样式 --- */
.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 24px;
    box-shadow: var(--card-shadow);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    transition: all var(--animation-speed) var(--bounce);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: left 0.6s;
}

.card:hover {
    transform: translateY(-8px) scale(1.02);
    box-shadow: var(--card-shadow-hover);
}

.card:hover::before {
    left: 100%;
}

.card-header {
    background: transparent;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    padding: 24px 32px;
    border-radius: 24px 24px 0 0;
}

.card-body {
    padding: 32px;
}

/* --- 按钮美化 --- */
.btn {
    border-radius: 16px;
    padding: 14px 32px;
    font-weight: 600;
    transition: all var(--animation-speed) var(--bounce);
    border: none;
    letter-spacing: 0.3px;
    position: relative;
    overflow: hidden;
    font-size: 0.95rem;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.btn:hover::before {
    left: 100%;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.3);
}

.btn-primary:hover {
    background: var(--gradient-hover);
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 12px 35px rgba(102, 126, 234, 0.4);
}

.btn-success {
    background: var(--gradient-blue);
    box-shadow: 0 6px 20px rgba(79, 172, 254, 0.3);
    color: white;
}

.btn-success:hover {
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 12px 35px rgba(79, 172, 254, 0.4);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.9);
    color: var(--text-main);
    border: 1px solid rgba(226, 232, 240, 0.8);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: rgba(248, 250, 252, 0.95);
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-2px);
}

/* --- 上传区域美化 --- */
.upload-area {
    border: 2px dashed rgba(203, 213, 225, 0.6);
    border-radius: 20px;
    background: var(--upload-area-bg);
    cursor: pointer;
    transition: all var(--animation-speed) ease;
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(10px);
}

.upload-area::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--gradient-soft);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.upload-area:hover,
.upload-area.drag-over {
    border-color: var(--primary-color);
    background: rgba(240, 249, 255, 0.9);
    transform: scale(1.02) translateY(-5px);
    box-shadow: 0 20px 40px rgba(102, 126, 234, 0.1);
}

.upload-area:hover::before,
.upload-area.drag-over::before {
    opacity: 0.1;
}

.upload-area i {
    color: var(--text-light);
    transition: all var(--animation-speed) var(--bounce);
    position: relative;
    z-index: 1;
}

.upload-area:hover i {
    color: var(--primary-color);
    transform: scale(1.2) rotate(5deg);
}

.upload-area .upload-text {
    position: relative;
    z-index: 1;
}

/* --- 表单元素 --- */
.form-control {
    background: var(--input-bg);
    border: 1px solid rgba(226, 232, 240, 0.8);
    border-radius: 14px;
    padding: 16px 20px;
    color: var(--text-main);
    transition: all var(--animation-speed) ease;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.02);
    backdrop-filter: blur(5px);
}

.form-control:focus {
    background: rgba(255, 255, 255, 0.98);
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.1);
    outline: none;
    transform: translateY(-2px);
}

.nav-tabs {
    border-bottom: 2px solid rgba(241, 245, 249, 0.8);
    margin-bottom: 0;
}

.nav-tabs .nav-link {
    border: none;
    color: var(--text-muted);
    font-weight: 600;
    padding: 14px 28px;
    border-radius: 16px 16px 0 0;
    transition: all var(--animation-speed) ease;
    background: transparent;
    position: relative;
    margin-bottom: 0;
}

.nav-tabs .nav-link::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 3px;
    background: var(--gradient-primary);
    transition: all var(--animation-speed) ease;
    transform: translateX(-50%);
    border-radius: 3px 3px 0 0;
}

.nav-tabs .nav-link.active {
    color: var(--primary-color);
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    margin-bottom: -2px;
}

.nav-tabs .nav-link.active::before {
    width: 100%;
}

.nav-tabs .nav-link:hover:not(.active) {
    color: var(--primary-color);
    background: rgba(255, 255, 255, 0.5);
    transform: translateY(-2px);
}

/* --- 分享ID显示特效 --- */
.share-id-display {
    font-size: 3.5rem;
    font-weight: 800;
    letter-spacing: 8px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: transparent;
    font-family: 'JetBrains Mono', 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', monospace;
    text-shadow: 0 10px 30px rgba(102, 126, 234, 0.3);
    animation: shareIdGlow 2s ease-in-out infinite alternate;
    position: relative;
    display: inline-block;
}

.share-id-display::before {
    content: attr(data-text);
    position: absolute;
    top: 0;
    left: 0;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: transparent;
    opacity: 0;
    animation: shareIdShimmer 3s ease-in-out infinite;
}

@keyframes shareIdGlow {
    0% {
        text-shadow: 0 0 20px rgba(102, 126, 234, 0.5),
                     0 0 40px rgba(118, 75, 162, 0.3);
    }
    100% {
        text-shadow: 0 0 30px rgba(102, 126, 234, 0.8),
                     0 0 60px rgba(118, 75, 162, 0.5);
    }
}

@keyframes shareIdShimmer {
    0%, 100% { opacity: 0; }
    50% { opacity: 0.3; }
}

/* --- 工具类修正 --- */
.text-primary {
    color: var(--primary-color) !important;
}

.bg-light {
    background-color: rgba(247, 250, 252, 0.8) !important;
}

.text-muted {
    color: var(--text-muted) !important;
}

/* 进度条美化 */
.progress {
    height: 10px;
    background-color: rgba(226, 232, 240, 0.6);
    border-radius: 10px;
    overflow: hidden;
    backdrop-filter: blur(5px);
}

.progress-bar {
    background: var(--gradient-primary);
    border-radius: 10px;
    transition: width 0.3s ease;
}

/* 上传进度样式 */
.upload-progress-container {
    background: rgba(255, 255, 255, 0.9);
    border: 1px solid rgba(255, 255, 255, 0.8);
    border-radius: 16px;
    padding: 1.5rem;
    backdrop-filter: blur(15px);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
    margin-top: 1rem;
    transition: all var(--animation-speed) ease;
}

.upload-progress-container:hover {
    transform: translateY(-2px);
    box-shadow: 0 15px 50px rgba(0, 0, 0, 0.15);
}

.upload-progress-container .progress {
    height: 8px;
    border-radius: 6px;
    background-color: rgba(102, 126, 234, 0.1);
    overflow: hidden;
}

.upload-progress-container .progress-bar {
    background: var(--gradient-primary);
    border-radius: 6px;
    transition: width 0.3s ease;
}

.upload-progress-container small {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
}

#uploadSpeed {
    color: var(--primary-color);
    font-weight: 600;
}

#remainingTime {
    color: var(--accent-color);
    font-weight: 600;
}



/* --- 页面加载动画 --- */
.animate-fade-in-up {
    animation: fadeInUp 0.8s ease-out;
}

.animate-fade-in {
    animation: fadeIn 0.6s ease-out;
}

.animate-slide-in-left {
    animation: slideInLeft 0.7s ease-out;
}

.animate-slide-in-right {
    animation: slideInRight 0.7s ease-out;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* --- 加载动画 --- */
.loading-spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 0.8s ease-in-out infinite;
}

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

/* --- 脉搏动画 --- */
.pulse {
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% {
        box-shadow: 0 0 0 0 rgba(102, 126, 234, 0.7);
    }
    70% {
        box-shadow: 0 0 0 10px rgba(102, 126, 234, 0);
    }
    100% {
        box-shadow: 0 0 0 0 rgba(102, 126, 234, 0);
    }
}

/* --- 内容查看器样式 --- */
.content-viewer {
    white-space: pre-wrap;
    word-break: break-word;
    background: rgba(255, 255, 255, 0.9);
    border: 1px solid rgba(226, 232, 240, 0.8);
    border-radius: 16px;
    padding: 24px;
    backdrop-filter: blur(10px);
    font-family: 'JetBrains Mono', 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', monospace;
    font-size: 0.9rem;
    line-height: 1.6;
    color: var(--text-main);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
}

.file-info {
    background: rgba(248, 250, 252, 0.9);
    border: 1px solid rgba(241, 245, 249, 0.8);
    border-radius: 16px;
    padding: 20px;
    margin-bottom: 24px;
    backdrop-filter: blur(10px);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.05);
}

.file-info h6 {
    color: var(--text-main);
    font-weight: 600;
    margin-bottom: 8px;
}

.file-info .text-muted {
    font-size: 0.9rem;
}

.share-sidebar-card {
    overflow: visible;
}

.share-tools-panel {
    background: rgba(248, 250, 252, 0.92);
    border: 1px solid rgba(226, 232, 240, 0.85);
    border-radius: 18px;
    padding: 18px;
    backdrop-filter: blur(12px);
}

.share-created-banner {
    border: none;
    background: linear-gradient(135deg, rgba(67, 233, 123, 0.15) 0%, rgba(79, 172, 254, 0.15) 100%);
    color: var(--text-main);
    border-radius: 18px;
}

.share-meta-alert {
    border: none;
    border-radius: 18px;
}

.share-id-row .share-id-display {
    margin-right: 0;
}

.share-stack-group > .form-control {
    min-width: 0;
}

.share-stack-group > .btn {
    white-space: nowrap;
}

/* Stabilize hover rendering on view page file area */
.view-main-card::before {
    display: none;
}

.view-main-card:hover {
    transform: none;
    box-shadow: var(--card-shadow);
}

#downloadBtn {
    background: var(--gradient-primary);
    transform: none;
    backface-visibility: hidden;
    will-change: box-shadow, filter;
    transition: box-shadow 0.2s ease, filter 0.2s ease;
    box-shadow: 0 7px 22px rgba(102, 126, 234, 0.3);
    animation: downloadBtnBreath 2.6s ease-in-out infinite;
}

#downloadBtn::before {
    display: none !important;
}

#downloadBtn:hover {
    background: var(--gradient-primary);
    transform: none;
    filter: brightness(1.04);
    animation-play-state: paused;
    box-shadow: 0 8px 24px rgba(102, 126, 234, 0.34);
}

#downloadBtn:active {
    transform: none;
    animation-play-state: paused;
    filter: brightness(0.99);
}

@keyframes downloadBtnBreath {
    0%, 100% {
        box-shadow: 0 7px 22px rgba(102, 126, 234, 0.3);
    }
    50% {
        box-shadow: 0 10px 28px rgba(102, 126, 234, 0.38);
    }
}

@media (prefers-reduced-motion: reduce) {
    #downloadBtn {
        animation: none;
    }
}

/* 响应式调整 */
@media (max-width: 768px) {
    .share-id-display {
        font-size: 2.5rem;
        letter-spacing: 4px;
    }

    .card-body {
        padding: 24px 20px;
    }

    .card-header {
        padding: 20px;
    }

    .btn {
        padding: 12px 24px;
        font-size: 0.9rem;
    }

    .nav-tabs .nav-link {
        padding: 12px 20px;
        font-size: 0.9rem;
    }

    .upload-area {
        border-radius: 16px;
    }

    .shape {
        opacity: 0.4;
    }

    .shape-1 {
        width: 400px;
        height: 400px;
    }

    .shape-2 {
        width: 350px;
        height: 350px;
    }

    .shape-3 {
        width: 300px;
        height: 300px;
    }

    .shape-4 {
        width: 250px;
        height: 250px;
    }

    .share-tools-panel {
        padding: 16px;
    }

    .share-stack-group {
        flex-wrap: wrap;
        gap: 0.75rem;
    }

    .share-stack-group > .form-control {
        width: 100% !important;
        border-radius: 14px !important;
    }

    .share-stack-group > .btn {
        width: 100%;
        border-radius: 14px !important;
    }
}

@media (max-width: 480px) {
    .share-id-display {
        font-size: 2rem;
        letter-spacing: 2px;
    }

    .card {
        border-radius: 20px;
        margin: 0.5rem;
    }

    .card-body {
        padding: 20px 16px;
    }

    .btn {
        padding: 10px 20px;
        font-size: 0.85rem;
        border-radius: 12px;
    }

    .form-control {
        padding: 14px 16px;
    }

    .upload-area {
        padding: 2rem 1rem;
    }

    .nav-tabs .nav-link {
        padding: 10px 16px;
        font-size: 0.85rem;
    }

    .share-id-row {
        align-items: stretch !important;
    }

    .share-id-row .share-id-display {
        width: 100%;
        text-align: center;
    }

    .share-id-row .btn {
        width: 100%;
    }

    .card-footer .d-flex {
        flex-wrap: wrap;
        gap: 0.75rem;
    }
}