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

body {
    background: linear-gradient(145deg, #0b0e1a 0%, #12162a 100%);
    font-family: 'Segoe UI', 'Fira Code', 'Courier New', monospace;
    padding: 2rem 1.5rem;
    color: #e3e6f0;
    min-height: 100vh;
}

/* 主容器 */
.container {
    max-width: 1400px;
    margin: 0 auto;
    backdrop-filter: blur(2px);
}

/* 标题区 */
.hero {
    text-align: center;
    margin-bottom: 2rem;
}
.hero h1 {
    font-size: 2.8rem;
    letter-spacing: 4px;
    background: linear-gradient(135deg, #c0e0ff, #9f7eff);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    text-shadow: 0 2px 5px rgba(0,0,0,0.2);
    font-weight: 700;
}
.hero p {
    color: #9aa4c2;
    margin-top: 0.5rem;
    font-size: 1rem;
}

/* 选项卡 */
.tabs {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
    border-bottom: 1px solid #2a2f45;
    padding-bottom: 0.75rem;
    flex-wrap: wrap;
}
.tab-btn {
    background: transparent;
    border: none;
    padding: 0.6rem 1.8rem;
    font-size: 1.2rem;
    font-weight: 600;
    font-family: inherit;
    color: #9aa4c2;
    cursor: pointer;
    transition: all 0.2s ease;
    border-radius: 40px;
    backdrop-filter: blur(4px);
}
.tab-btn.active {
    background: #2a2f55;
    color: white;
    box-shadow: 0 4px 12px rgba(0,0,0,0.3);
    border: 1px solid #4c5b9a;
}
.tab-btn:hover:not(.active) {
    color: #cfdcff;
    background: #1e223b;
}

/* 双面板 (每个模式单独内容, 用display控制) */
.mode-panel {
    display: none;
    animation: fadeIn 0.25s ease;
}
.mode-panel.active-panel {
    display: block;
}
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(6px);}
    to { opacity: 1; transform: translateY(0);}
}

/* 通用卡片样式 */
.card {
    background: rgba(18, 22, 42, 0.7);
    backdrop-filter: blur(8px);
    border-radius: 32px;
    padding: 1.5rem;
    margin-bottom: 1.8rem;
    border: 1px solid rgba(72, 85, 120, 0.4);
    box-shadow: 0 20px 35px -12px rgba(0,0,0,0.4);
}

.grid-2col {
    display: grid;
    grid-template-columns: 1fr 1.2fr;
    gap: 1.8rem;
}
@media (max-width: 760px) {
    .grid-2col {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    body {
        padding: 1rem;
    }
    .hero h1 {
        font-size: 2rem;
    }
}

/* 控件组 */
.control-group {
    margin-bottom: 1.3rem;
}
label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: #bfc9f0;
    font-size: 0.9rem;
    letter-spacing: 0.5px;
}
input, select, textarea {
    width: 100%;
    background: #0c0f1c;
    border: 1px solid #2e3456;
    padding: 0.7rem 1rem;
    border-radius: 20px;
    color: #f0f3ff;
    font-family: monospace;
    font-size: 0.9rem;
    transition: all 0.2s;
}
input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: #7f92ff;
    box-shadow: 0 0 0 2px rgba(127, 146, 255, 0.2);
}
button {
    background: #2c315c;
    border: none;
    padding: 0.7rem 1.4rem;
    border-radius: 40px;
    font-weight: bold;
    color: white;
    font-family: inherit;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.9rem;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}
button.primary {
    background: #6d5dfe;
    box-shadow: 0 4px 12px rgba(109, 93, 254, 0.3);
}
button.primary:hover {
    background: #8a7cff;
    transform: translateY(-2px);
}
button:hover {
    background: #3d4379;
    transform: translateY(-1px);
}
.flex-btns {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    margin-top: 0.8rem;
}

/* 预览区域 */
.preview-img {
    background: #090c18;
    border-radius: 24px;
    padding: 1rem;
    text-align: center;
    border: 1px dashed #3d4370;
}
.preview-img img {
    max-width: 100%;
    max-height: 220px;
    border-radius: 16px;
    object-fit: contain;
}
.upload-area {
    border: 2px dashed #4a5080;
    background: #0b0e1c;
    border-radius: 28px;
    padding: 1rem;
    text-align: center;
    cursor: pointer;
    transition: 0.2s;
}
.upload-area:hover {
    border-color: #8f9eff;
    background: #11162c;
}

/* ascii 结果区 */
.result-box {
    background: #03050c;
    border-radius: 24px;
    padding: 1.2rem;
    border: 1px solid #2f3560;
}
.result-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    margin-bottom: 1rem;
}
pre {
    font-family: 'Fira Code', 'Courier New', monospace;
    font-size: 12px;
    line-height: 1.3;
    white-space: pre;
    overflow-x: auto;
    background: #010101;
    padding: 1rem;
    border-radius: 20px;
    max-height: 500px;
    color: #d3deff;
    border: 1px solid #262d4a;
}
.info-tip {
    font-size: 0.75rem;
    color: #7b84af;
    margin-top: 0.5rem;
}
.range-value {
    display: inline-block;
    background: #1f253f;
    padding: 0.2rem 0.8rem;
    border-radius: 30px;
    font-size: 0.8rem;
    margin-left: 8px;
}
hr {
    border-color: #2a2f4e;
    margin: 0.5rem 0;
}
.char-preview {
    font-family: monospace;
    letter-spacing: 2px;
}
footer {
    text-align: center;
    margin-top: 3rem;
    font-size: 0.8rem;
    color: #5f6990;
}