CSS — Forms

The baseline reset

Form controls ignore inheritance by default — force consistency:

input,
select,
textarea,
button {
    font: inherit;
    color: inherit;
}

The input recipe

.field {
    margin-bottom: 16px;
}

.field label {
    display: block;
    font-weight: 600;
    font-size: .875rem;
    margin-bottom: 6px;
}

.field input {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid #cbd5e1;
    border-radius: 8px;
    transition: border-color .2s, box-shadow .2s;
}

.field input:focus {
    outline: none;
    border-color: #0d9488;
    box-shadow: 0 0 0 3px rgba(13,148,136,.25);
}

(Comfortable rounded inputs whose teal focus ring appears only when active.)

width:100% + the container controlling size = inputs that adapt to any layout. Pair labels with for="id" so clicking focuses.

States that communicate

input:hover:not(:focus) { border-color: #94a3b8; }

input:user-invalid {           /* modern: after user typed wrong */
    border-color: #dc2626;
}
input:user-valid {
    border-color: #16a34a;
}

input:disabled {
    background: #f1f5f9;
    cursor: not-allowed;
}

::placeholder { color: #94a3b8; }

Pair color signals with icons/text — color alone fails accessibility.

Selects, textareas, resize

textarea {
    min-height: 120px;
    resize: vertical;        /* allow height drag only */
}

select {
    appearance: none;                       /* drop native arrow   */
    background-image: url("chevron.svg");   /* custom arrow        */
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 36px;
}

Checkboxes & radios — custom look

Style the label via the checked state:

.check {
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
}
.check input { accent-color: #0d9488; width: 18px; height: 18px; }

accent-color recolors native checkboxes/radios/progress in one line — 95% of the custom-checkbox need gone.

Fully bespoke (switch style):

.switch input { position: absolute; opacity: 0; }      /* keep accessible! */
.switch span {
    width: 44px; height: 24px;
    background: #cbd5e1; border-radius: 999px;
    position: relative; transition: background .2s;
}
.switch span::after {
    content: "";
    position: absolute;
    top: 2px; left: 2px;
    width: 20px; height: 20px;
    background: white; border-radius: 50%;
    transition: translate .2s;
}
.switch input:checked + span { background: #0d9488; }
.switch input:checked + span::after { translate: 20px 0; }
.switch input:focus-visible + span { outline: 2px solid #0d9488; }

The hidden-but-present input keeps keyboard + screen-reader support.

Form layout patterns

/* stacked (mobile default) — see field above */

/* two-column rows on wide screens */
.form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}
.form-grid .full { grid-column: 1 / -1; }

<form class="form-grid">
    <div class="field">First name</div>
    <div class="field">Last name</div>
    <div class="field full">Email</div>
</form>

Checklist: label every input · visible :focus-visible · real error text (not red borders alone) · autocomplete attributes · generous touch targets.

Mini Practice

1. Styled login card: email + password + button.
2. Focus rings + hover borders + placeholder colors.
3. accent-colored checkboxes; then one custom switch.
4. Two-column grid collapsing to one under 600px.
5. Native validation styled via user-invalid with helper text.

Next: counters →