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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #64748b;
    --danger-color: #ef4444;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --background: #f8fafc;
    --surface: #ffffff;
    --border: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
}

/* Header & Navigation */
header {
    background-color: var(--surface);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

header h1 {
    font-size: 1.75rem;
    color: var(--primary-color);
}

nav {
    display: flex;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    transition: all 0.3s ease;
}

.nav-link:hover {
    color: var(--primary-color);
    background-color: #eff6ff;
}

.nav-link.active {
    color: var(--primary-color);
    background-color: #eff6ff;
    border-bottom: 2px solid var(--primary-color);
}

/* Container */
.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Main Content */
main {
    padding: 2rem 0;
    min-height: calc(100vh - 120px);
}

.content-section {
    background-color: var(--surface);
    border-radius: 8px;
    padding: 2rem;
    box-shadow: var(--shadow);
}

.content-section h2 {
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
}

/* Controls (Search & Sort) */
.controls {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.search-input,
.sort-select {
    padding: 0.75rem;
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

.search-input {
    flex: 1;
    min-width: 200px;
}

.search-input:focus,
.sort-select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.sort-select {
    min-width: 150px;
}

/* Files Container */
.files-container {
    display: grid;
    gap: 1rem;
}

.file-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    background-color: var(--background);
    transition: all 0.3s ease;
}

.file-item:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.file-info {
    flex: 1;
}

.file-name {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.file-meta {
    display: flex;
    gap: 1rem;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.file-meta span {
    display: flex;
    align-items: center;
}

.file-actions {
    display: flex;
    gap: 0.5rem;
}

/* Buttons */
.btn {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 4px;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    white-space: nowrap;
}

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

.btn-primary:hover:not(:disabled) {
    background-color: var(--primary-hover);
    box-shadow: var(--shadow-lg);
}

.btn-primary:disabled {
    background-color: #cbd5e1;
    cursor: not-allowed;
}

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

.btn-secondary:hover {
    background-color: #475569;
    box-shadow: var(--shadow-lg);
}

.btn-sm {
    padding: 0.375rem 0.75rem;
    font-size: 0.8rem;
}

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

.btn-danger:hover {
    background-color: #dc2626;
}

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

.btn-success:hover {
    background-color: #059669;
}

/* Upload Form */
.upload-form {
    max-width: 600px;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.file-input-wrapper {
    position: relative;
    display: inline-block;
    width: 100%;
    padding: 2rem;
    border: 2px dashed var(--border);
    border-radius: 6px;
    background-color: var(--background);
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
}

.file-input-wrapper:hover,
.file-input-wrapper.dragover {
    border-color: var(--primary-color);
    background-color: #eff6ff;
}

.file-input-wrapper.dragover {
    box-shadow: var(--shadow-lg);
}

.file-input {
    position: absolute;
    opacity: 0;
    width: 100%;
    height: 100%;
    cursor: pointer;
}

.file-input-label {
    pointer-events: none;
    color: var(--text-secondary);
}

.form-group small {
    display: block;
    margin-top: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

/* Files List (Upload) */
.files-list {
    margin: 1.5rem 0;
    padding: 1rem;
    background-color: var(--background);
    border-radius: 6px;
    border-left: 4px solid var(--primary-color);
}

.files-list h3 {
    margin-bottom: 0.75rem;
    font-size: 1rem;
}

.files-list ul {
    list-style: none;
}

.files-list li {
    padding: 0.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.files-list li .file-size {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.files-list li .remove-file {
    color: var(--danger-color);
    cursor: pointer;
    font-size: 1.25rem;
    line-height: 1;
}

.files-list li .remove-file:hover {
    color: #dc2626;
}

/* Form Actions */
.form-actions {
    display: flex;
    gap: 1rem;
    margin-top: 2rem;
}

.form-actions .btn {
    flex: 1;
    justify-content: center;
}

/* Feedback Messages */
.feedback {
    margin: 1rem 0;
    padding: 1rem;
    border-radius: 6px;
    border-left: 4px solid var(--border);
}

.feedback.success {
    background-color: #ecfdf5;
    border-color: var(--success-color);
    color: #047857;
}

.feedback.error {
    background-color: #fef2f2;
    border-color: var(--danger-color);
    color: #991b1b;
}

.feedback.warning {
    background-color: #fffbeb;
    border-color: var(--warning-color);
    color: #92400e;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.empty-state p {
    font-size: 1.1rem;
    margin-bottom: 1rem;
}

.empty-state a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
}

.empty-state a:hover {
    text-decoration: underline;
}

/* Info Box */
.info-box {
    margin-top: 2rem;
    padding: 1rem;
    background-color: #eff6ff;
    border-left: 4px solid var(--primary-color);
    border-radius: 6px;
}

.info-box h3 {
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.info-box p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.info-box p + p {
    margin-top: 0.5rem;
}

/* Footer */
footer {
    background-color: var(--text-primary);
    color: white;
    text-align: center;
    padding: 1.5rem;
    margin-top: 2rem;
}

footer p {
    font-size: 0.875rem;
}

/* Responsive */
@media (max-width: 768px) {
    header .container {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }

    header h1 {
        font-size: 1.5rem;
    }

    nav {
        gap: 1rem;
        justify-content: center;
    }

    .controls {
        flex-direction: column;
    }

    .search-input,
    .sort-select {
        width: 100%;
    }

    .file-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
    }

    .file-actions {
        width: 100%;
    }

    .file-actions .btn {
        flex: 1;
    }

    .form-actions {
        flex-direction: column;
    }

    .form-actions .btn {
        width: 100%;
    }

    main {
        padding: 1rem 0;
    }

    .content-section {
        padding: 1rem;
    }
}