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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --success-color: #22c55e;
    --error-color: #ef4444
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px
}

header {
    background: var(--card-bg);
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none
}

nav ul {
    display: flex;
    list-style: none;
    gap: 2rem
}

nav a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s
}

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

main {
    padding: 2rem 0;
    min-height: calc(100vh - 200px)
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem
}

.tool-card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    transition: transform 0.3s, box-shadow 0.3s;
    cursor: pointer;
    text-decoration: none;
    color: inherit;
    display: block
}

.tool-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15)
}

.tool-icon {
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, var(--primary-color), #3b82f6);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
    font-size: 1.5rem
}

.tool-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary)
}

.tool-desc {
    color: var(--text-secondary);
    font-size: 0.9rem
}

.tool-page {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    max-width: 800px;
    margin: 0 auto
}

.tool-header {
    margin-bottom: 2rem;
    text-align: center
}

.tool-header h1 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary)
}

.tool-header p {
    color: var(--text-secondary)
}

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    padding: 3rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
    margin-bottom: 2rem
}

.upload-area:hover {
    border-color: var(--primary-color);
    background: #f0f7ff
}

.upload-area.dragover {
    border-color: var(--primary-color);
    background: #e0f2fe
}

.upload-icon {
    font-size: 3rem;
    margin-bottom: 1rem
}

.upload-text {
    color: var(--text-secondary);
    margin-bottom: 1rem
}

.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.3s;
    border: none;
    font-size: 1rem
}

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

.btn-primary:hover {
    background: var(--primary-hover)
}

.btn-secondary {
    background: var(--border-color);
    color: var(--text-primary)
}

.btn-secondary:hover {
    background: #cbd5e1
}

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

.btn-success:hover {
    background: #16a34a
}

.control-group {
    margin-bottom: 1.5rem
}

.control-label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary)
}

.control-input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s
}

.control-input:focus {
    outline: none;
    border-color: var(--primary-color)
}

.control-select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    background: white;
    cursor: pointer
}

.control-range {
    width: 100%;
    margin: 0.5rem 0
}

.preview-area {
    margin-top: 2rem;
    text-align: center
}

.preview-image {
    max-width: 100%;
    max-height: 500px;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1)
}

.result-area {
    margin-top: 2rem;
    padding: 1.5rem;
    background: #f0fdf4;
    border-radius: 8px;
    display: none
}

.result-area.show {
    display: block
}

.result-title {
    font-weight: 600;
    color: var(--success-color);
    margin-bottom: 1rem
}

.file-input {
    display: none
}

.back-link {
    display: inline-block;
    margin-bottom: 1rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem
}

.back-link:hover {
    color: var(--primary-color)
}

footer {
    background: var(--card-bg);
    border-top: 1px solid var(--border-color);
    padding: 2rem 0;
    margin-top: 3rem;
    text-align: center
}

footer p {
    color: var(--text-secondary);
    font-size: 0.9rem
}

@media (max-width: 768px) {
    .container {
        padding: 0 15px
    }
    
    .header-content {
        flex-direction: column;
        gap: 1rem
    }
    
    nav ul {
        flex-wrap: wrap;
        justify-content: center;
        gap: 1rem
    }
    
    .tools-grid {
        grid-template-columns: 1fr
    }
    
    .tool-page {
        padding: 1.5rem
    }
    
    .upload-area {
        padding: 2rem 1rem
    }
    
    .tool-header h1 {
        font-size: 1.5rem
    }
}

@media (max-width: 480px) {
    .tool-card {
        padding: 1rem
    }
    
    .tool-icon {
        width: 40px;
        height: 40px;
        font-size: 1.25rem
    }
    
    .tool-title {
        font-size: 1.1rem
    }
    
    .btn {
        width: 100%;
        text-align: center
    }
}