Svelte Guideline: Logic — Use {#if} for conditionals. Description: Template conditionals. Do: {#if} {:else if} {:else}. Don't: Ternary in expressions. Good Example: {#if cond}...{:else}...{/if}. Bad Example: {cond ? a : b} for complex. Severity: Low. Docs: https://svelte.dev/docs/logic-blocks#if.