mastodon/app/assets/stylesheets/forms.scss

code {
  font-family: 'Roboto Mono', monospace;
  font-weight: 400;
}

.form-container {
  max-width: 400px;
  padding: 20px;
  margin: 0 auto;
}

.simple_form {
  .input {
    margin-bottom: 15px;
  }

  .hint {
    display: block;
    color: rgba(255, 255, 255, 0.8);
    font-size: 12px;
  }

  .input.file, .input.select {
    padding: 15px 0;
    margin-bottom: 0;
    display: flex;

    label {
      font-family: inherit;
      font-size: 16px;
      color: #fff;
      width: 100px;
      display: block;
      flex: 0 0 auto;
      padding-top: 5px;
    }

    input[type=file], select {
      flex: 1 1 auto;
    }
  }

  .fields-group {
    margin-bottom: 25px;
  }

  .input.boolean {
    margin-bottom: 5px;

    label {
      font-family: inherit;
      font-size: 14px;
      color: white;
      display: block;
    }

    label.checkbox {
      position: relative;
	    padding-left: 25px;
    }

    input[type=checkbox] {
	    position: absolute;
	    left: 0;
      top: 1px;
      margin: 0;
    }

    .hint {
      padding-left: 25px;
    }
  }

  input[type=text], input[type=email], input[type=password], textarea {
    background: transparent;
    box-sizing: border-box;
    border: 0;
    border-bottom: 2px solid #9baec8;
    border-radius: 2px 2px 0 0;
    padding: 7px 4px;
    font-size: 16px;
    color: #fff;
    display: block;
    width: 100%;
    outline: 0;
    font-family: inherit;

    &:invalid {
      box-shadow: none;
    }

    &:focus:invalid {
      border-bottom-color: #df405a;
    }

    &:required:valid {
      border-bottom-color: #79bd9a;
    }

    &:active, &:focus {
      border-bottom-color: #2b90d9;
      background: rgba(0, 0, 0, 0.1);
    }
  }

  .input.field_with_errors {
    input[type=text], input[type=email], input[type=password] {
      border-bottom-color: #df405a;
    }

    .error {
      font-weight: 500;
      color: #df405a;
    }
  }

  .actions {
    margin-top: 30px;
  }

  button {
    display: block;
    width: 100%;
    border: 0;
    border-radius: 4px;
    background: #2b90d9;
    color: #fff;
    font-size: 18px;
    padding: 10px;
    text-transform: uppercase;
    cursor: pointer;
    font-weight: 500;
    outline: 0;
    margin-bottom: 10px;

    &:hover {
      background-color: lighten(#2b90d9, 5%);
    }

    &:active, &:focus {
      position: relative;
      top: 1px;
      background-color: darken(#2b90d9, 5%);
    }

    &.negative {
      background: #df405a;

      &:hover {
        background-color: lighten(#df405a, 5%);
      }

      &:active, &:focus {
        background-color: darken(#df405a, 5%);
      }
    }
  }
}

.flash-message {
  background: #282c37;
  color: #9baec8;
  border-radius: 4px;
  padding: 15px 10px;
  margin-bottom: 30px;
  box-shadow: 0 0 5px rgba(0, 0, 0, 0.2);
  text-align: center;

  strong {
    font-weight: 500;
  }
}

.form-footer {
  margin-top: 30px;
  text-align: center;

  a {
    color: white;
    text-decoration: none;

    &:hover {
      text-decoration: underline;
    }
  }
}

.oauth-prompt, .follow-prompt {
  margin-bottom: 30px;
  text-align: center;
  color: #9baec8;

  h2 {
    font-size: 16px;
    margin-bottom: 30px;
  }

  strong {
    color: #d9e1e8;
    font-weight: 500;
  }
}