/* --- 默认明亮主题 --- */
:root {
    --primary-color: #007bff;
    --tool-bg: #f0f2f5;
    --panel-bg: #ffffff;
    --border-color: #dee2e6;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --success-color: #198754;
    --secondary-btn-bg: #6c757d;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: var(--tool-bg);
    margin: 0;
    padding: 20px;
    color: var(--text-primary);
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    display: flex;
    gap: 20px;
    max-width: 1200px;
    margin: 0 auto;
    background-color: var(--panel-bg);
    padding: 20px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.settings-panel { width: 300px; flex-shrink: 0; }
.results-panel { flex-grow: 1; display: flex; gap: 20px; }

.upload-area-container {
    border: 2px dashed var(--border-color);
    padding: 20px;
    text-align: center;
    border-radius: 12px;
    cursor: pointer;
    transition: all .3s;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}
.upload-area-container:hover, .upload-area-container.dragover {
    border-color: var(--primary-color);
    background-color: #f8faff;
}
.upload-area-container .upload-icon { width: 40px; height: 40px; margin-bottom: 10px; color: var(--text-secondary); }
.upload-area-container .upload-text { font-size: 16px; font-weight: 500; color: var(--text-primary); margin: 0; }
.upload-area-container .upload-hint { font-size: 14px; color: var(--text-secondary); margin: 0; }
.upload-area-container .upload-button-alt { margin-top: 10px; font-size: 14px; padding: 8px 15px; background-color: var(--secondary-btn-bg); color: white; border: none; border-radius: 5px; }

.button, button {
    display: inline-block; background: var(--primary-color); color: white;
    padding: 10px 15px; border-radius: 5px; text-decoration: none;
    border: none; cursor: pointer; font-size: 14px; width: 100%;
    box-sizing: border-box;
}
button:hover, .button:not(.disabled):hover { background: #0b5ed7; }
.button.disabled { background-color: #aaa; color: #fff; cursor: not-allowed; }

.options h3 { margin-top: 20px; border-bottom: 1px solid var(--border-color); padding-bottom: 10px; }
.option-group { margin: 15px 0; }
.option-group label { display: block; margin-bottom: 5px; font-size: 14px; color: var(--text-secondary); }
.option-note { font-size: 12px; color: var(--text-secondary); text-align: center; margin-top: -10px; }
input[type="range"] { width: 100%; }

.image-box {
    flex: 1; background-color: var(--tool-bg); border: 1px solid var(--border-color);
    border-radius: 8px; padding: 15px; text-align: center; display: flex;
    flex-direction: column; align-items: center; justify-content: center;
    position: relative; min-height: 200px;
}
.image-box h3 { margin: 0 0 10px; text-align: center; }
.image-box img { max-width: 100%; max-height: 300px; margin-bottom: 15px; display: none; border-radius: 4px; }
.image-box p { margin: 5px 0; font-size: 14px; font-weight: 500; }
#reductionInfo { color: var(--success-color); font-size: 18px; font-weight: bold; }

.loader {
    border: 4px solid #e9ecef; border-top: 4px solid var(--primary-color);
    border-radius: 50%; width: 40px; height: 40px;
    animation: spin 1s linear infinite; position: absolute;
}
@keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }

@media (max-width: 900px) {
    .container, .results-panel { flex-direction: column; }
    .settings-panel { width: 100%; }
}

/* --- 暗黑模式覆盖 --- */
body.dark-mode {
    --primary-color: #3d8bfd;
    --tool-bg: #1e2128;
    --panel-bg: #2a2e37;
    --border-color: #4a505f;
    --text-primary: #e5e7eb;
    --text-secondary: #9ca3af;
    --success-color: #20c997;
    --secondary-btn-bg: #4a505f;
}

body.dark-mode button:hover, 
body.dark-mode .button:not(.disabled):hover { 
    background: #4c9aff; 
}

body.dark-mode .upload-area-container:hover,
body.dark-mode .upload-area-container.dragover {
    background-color: var(--tool-bg);
}

body.dark-mode .button.disabled {
    background-color: #555;
    color: #888;
}

body.dark-mode .loader {
    border-color: #444;
    border-top-color: var(--primary-color);
}