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

body {
    font-family: 'Inter', Arial, sans-serif;
    background: #fff;
    color: #111;
    padding: 32px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    border: 4px solid #111;
    padding: 32px;
    background: #fff;
    display: flex;
    gap: 32px;
}

.editor-section, .preview-section {
    flex: 1;
    min-width: 0;
    display: flex;
    flex-direction: column;
    background: #fff;
    min-height: 400px;
    height: 80vh;
}

#mermaid-input {
    flex: 1;
    min-height: 300px;
    resize: vertical;
}

#mermaid-preview {
    min-height: 300px;
    background: #fff;
    border: none;
    margin-top: 0;
    margin-bottom: 0;
    padding: 0;
    box-shadow: none;
    border-radius: 0;
    flex: 1;
    overflow: hidden;
    position: relative;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

#mermaid-preview svg {
    max-width: 100%;
    max-height: 100%;
    display: block;
}

h1, .main-title {
    font-size: 2rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 2px;
    margin-bottom: 16px;
    margin-top: 0;
}

hr, .main-title-underline {
    border: none;
    border-top: 4px solid #111;
    margin: 0 0 32px 0;
}

.section-box {
    border: 3px solid #111;
    padding: 24px;
    margin-bottom: 32px;
    background: #fff;
}

.section-title {
    font-size: 1rem;
    font-weight: 700;
    text-transform: uppercase;
    margin-bottom: 12px;
    letter-spacing: 1px;
}

input[type="text"], textarea {
    width: 100%;
    font-size: 1.2rem;
    padding: 16px;
    border: 3px solid #111;
    background: #fff;
    color: #111;
    margin-top: 8px;
    margin-bottom: 0;
    outline: none;
    font-family: inherit;
    font-weight: 400;
    box-shadow: none;
    border-radius: 0;
}

input[type="text"]::placeholder, textarea::placeholder {
    color: #bbb;
    font-weight: 400;
}

#error-message {
    min-height: 20px;
    color: #dc3545;
    font-size: 14px;
    margin-top: 10px;
}

.button-group {
    display: flex;
    gap: 16px;
    margin-bottom: 32px;
}

#export-btn, #export-svg-btn, #reset-btn {
    flex: 1;
    margin: 0;
    padding: 12px;
    font-size: 1rem;
    font-weight: 700;
    text-transform: uppercase;
    border: 3px solid #111;
    background: #fff;
    color: #111;
    cursor: pointer;
    border-radius: 0;
    box-shadow: none;
    transition: background 0.1s;
}

#export-btn:hover, #export-svg-btn:hover, #reset-btn:hover {
    background: #f5f5f5;
}

@media (max-width: 900px) {
    .container {
        flex-direction: column;
        gap: 0;
        padding: 12px;
    }
    .editor-section, .preview-section {
        min-height: 200px;
        padding: 12px;
        margin-bottom: 24px;
    }
}